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diff --git a/doc/manual/src/SUMMARY.md b/doc/manual/src/SUMMARY.md new file mode 100644 index 000000000..8281f683f --- /dev/null +++ b/doc/manual/src/SUMMARY.md @@ -0,0 +1,105 @@ +# Table of Contents + +- [Introduction](introduction.md) +- [Quick Start](quick-start.md) +- [Installation](installation/installation.md) + - [Supported Platforms](installation/supported-platforms.md) + - [Installing a Binary Distribution](installation/installing-binary.md) + - [Installing Nix from Source](installation/installing-source.md) + - [Prerequisites](installation/prerequisites-source.md) + - [Obtaining a Source Distribution](installation/obtaining-source.md) + - [Building Nix from Source](installation/building-source.md) + - [Security](installation/nix-security.md) + - [Single-User Mode](installation/single-user.md) + - [Multi-User Mode](installation/multi-user.md) + - [Environment Variables](installation/env-variables.md) + - [Upgrading Nix](installation/upgrading.md) +- [Package Management](package-management/package-management.md) + - [Basic Package Management](package-management/basic-package-mgmt.md) + - [Profiles](package-management/profiles.md) + - [Garbage Collection](package-management/garbage-collection.md) + - [Garbage Collector Roots](package-management/garbage-collector-roots.md) + - [Channels](package-management/channels.md) + - [Sharing Packages Between Machines](package-management/sharing-packages.md) + - [Serving a Nix store via HTTP](package-management/binary-cache-substituter.md) + - [Copying Closures via SSH](package-management/copy-closure.md) + - [Serving a Nix store via SSH](package-management/ssh-substituter.md) + - [Serving a Nix store via S3](package-management/s3-substituter.md) +- [Writing Nix Expressions](expressions/writing-nix-expressions.md) + - [A Simple Nix Expression](expressions/simple-expression.md) + - [Expression Syntax](expressions/expression-syntax.md) + - [Build Script](expressions/build-script.md) + - [Arguments and Variables](expressions/arguments-variables.md) + - [Building and Testing](expressions/simple-building-testing.md) + - [Generic Builder Syntax](expressions/generic-builder.md) + - [Writing Nix Expressions](expressions/expression-language.md) + - [Values](expressions/language-values.md) + - [Language Constructs](expressions/language-constructs.md) + - [Operators](expressions/language-operators.md) + - [Derivations](expressions/derivations.md) + - [Advanced Attributes](expressions/advanced-attributes.md) + - [Built-in Constants](expressions/builtin-constants.md) + - [Built-in Functions](expressions/builtins.md) +- [Advanced Topics](advanced-topics/advanced-topics.md) + - [Remote Builds](advanced-topics/distributed-builds.md) + - [Tuning Cores and Jobs](advanced-topics/cores-vs-jobs.md) + - [Verifying Build Reproducibility](advanced-topics/diff-hook.md) + - [Using the `post-build-hook`](advanced-topics/post-build-hook.md) +- [Command Reference](command-ref/command-ref.md) + - [Common Options](command-ref/opt-common.md) + - [Common Environment Variables](command-ref/env-common.md) + - [Main Commands](command-ref/main-commands.md) + - [nix-env](command-ref/nix-env.md) + - [nix-build](command-ref/nix-build.md) + - [nix-shell](command-ref/nix-shell.md) + - [nix-store](command-ref/nix-store.md) + - [Utilities](command-ref/utilities.md) + - [nix-channel](command-ref/nix-channel.md) + - [nix-collect-garbage](command-ref/nix-collect-garbage.md) + - [nix-copy-closure](command-ref/nix-copy-closure.md) + - [nix-daemon](command-ref/nix-daemon.md) + - [nix-hash](command-ref/nix-hash.md) + - [nix-instantiate](command-ref/nix-instantiate.md) + - [nix-prefetch-url](command-ref/nix-prefetch-url.md) + - [Experimental Commands](command-ref/experimental-commands.md) + - [nix](command-ref/nix.md) + - [Files](command-ref/files.md) + - [nix.conf](command-ref/conf-file.md) +- [Glossary](glossary.md) +- [Hacking](hacking.md) +- [Release Notes](release-notes/release-notes.md) + - [Release 2.3 (2019-09-04)](release-notes/rl-2.3.md) + - [Release 2.2 (2019-01-11)](release-notes/rl-2.2.md) + - [Release 2.1 (2018-09-02)](release-notes/rl-2.1.md) + - [Release 2.0 (2018-02-22)](release-notes/rl-2.0.md) + - [Release 1.11.10 (2017-06-12)](release-notes/rl-1.11.10.md) + - [Release 1.11 (2016-01-19)](release-notes/rl-1.11.md) + - [Release 1.10 (2015-09-03)](release-notes/rl-1.10.md) + - [Release 1.9 (2015-06-12)](release-notes/rl-1.9.md) + - [Release 1.8 (2014-12-14)](release-notes/rl-1.8.md) + - [Release 1.7 (2014-04-11)](release-notes/rl-1.7.md) + - [Release 1.6.1 (2013-10-28)](release-notes/rl-1.6.1.md) + - [Release 1.6 (2013-09-10)](release-notes/rl-1.6.md) + - [Release 1.5.2 (2013-05-13)](release-notes/rl-1.5.2.md) + - [Release 1.5 (2013-02-27)](release-notes/rl-1.5.md) + - [Release 1.4 (2013-02-26)](release-notes/rl-1.4.md) + - [Release 1.3 (2013-01-04)](release-notes/rl-1.3.md) + - [Release 1.2 (2012-12-06)](release-notes/rl-1.2.md) + - [Release 1.1 (2012-07-18)](release-notes/rl-1.1.md) + - [Release 1.0 (2012-05-11)](release-notes/rl-1.0.md) + - [Release 0.16 (2010-08-17)](release-notes/rl-0.16.md) + - [Release 0.15 (2010-03-17)](release-notes/rl-0.15.md) + - [Release 0.14 (2010-02-04)](release-notes/rl-0.14.md) + - [Release 0.13 (2009-11-05)](release-notes/rl-0.13.md) + - [Release 0.12 (2008-11-20)](release-notes/rl-0.12.md) + - [Release 0.11 (2007-12-31)](release-notes/rl-0.11.md) + - [Release 0.10.1 (2006-10-11)](release-notes/rl-0.10.1.md) + - [Release 0.10 (2006-10-06)](release-notes/rl-0.10.md) + - [Release 0.9.2 (2005-09-21)](release-notes/rl-0.9.2.md) + - [Release 0.9.1 (2005-09-20)](release-notes/rl-0.9.1.md) + - [Release 0.9 (2005-09-16)](release-notes/rl-0.9.md) + - [Release 0.8.1 (2005-04-13)](release-notes/rl-0.8.1.md) + - [Release 0.8 (2005-04-11)](release-notes/rl-0.8.md) + - [Release 0.7 (2005-01-12)](release-notes/rl-0.7.md) + - [Release 0.6 (2004-11-14)](release-notes/rl-0.6.md) + - [Release 0.5 and earlier](release-notes/rl-0.5.md) diff --git a/doc/manual/src/advanced-topics/advanced-topics.md b/doc/manual/src/advanced-topics/advanced-topics.md new file mode 100644 index 000000000..8b1378917 --- /dev/null +++ b/doc/manual/src/advanced-topics/advanced-topics.md @@ -0,0 +1 @@ + diff --git a/doc/manual/src/advanced-topics/cores-vs-jobs.md b/doc/manual/src/advanced-topics/cores-vs-jobs.md new file mode 100644 index 000000000..4a9058ca1 --- /dev/null +++ b/doc/manual/src/advanced-topics/cores-vs-jobs.md @@ -0,0 +1,39 @@ +# Tuning Cores and Jobs + +Nix has two relevant settings with regards to how your CPU cores will +be utilized: `cores` and `max-jobs`. This chapter will talk about what +they are, how they interact, and their configuration trade-offs. + + - `max-jobs` + Dictates how many separate derivations will be built at the same + time. If you set this to zero, the local machine will do no + builds. Nix will still substitute from binary caches, and build + remotely if remote builders are configured. + + - `cores` + Suggests how many cores each derivation should use. Similar to + `make -j`. + +The `cores` setting determines the value of +`NIX_BUILD_CORES`. `NIX_BUILD_CORES` is equal to `cores`, unless +`cores` equals `0`, in which case `NIX_BUILD_CORES` will be the total +number of cores in the system. + +The maximum number of consumed cores is a simple multiplication, +`max-jobs` \* `NIX_BUILD_CORES`. + +The balance on how to set these two independent variables depends upon +each builder's workload and hardware. Here are a few example scenarios +on a machine with 24 cores: + +| `max-jobs` | `cores` | `NIX_BUILD_CORES` | Maximum Processes | Result | +| --------------------- | ------------------ | ----------------- | ----------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | +| 1 | 24 | 24 | 24 | One derivation will be built at a time, each one can use 24 cores. Undersold if a job can’t use 24 cores. | +| 4 | 6 | 6 | 24 | Four derivations will be built at once, each given access to six cores. | +| 12 | 6 | 6 | 72 | 12 derivations will be built at once, each given access to six cores. This configuration is over-sold. If all 12 derivations being built simultaneously try to use all six cores, the machine's performance will be degraded due to extensive context switching between the 12 builds. | +| 24 | 1 | 1 | 24 | 24 derivations can build at the same time, each using a single core. Never oversold, but derivations which require many cores will be very slow to compile. | +| 24 | 0 | 24 | 576 | 24 derivations can build at the same time, each using all the available cores of the machine. Very likely to be oversold, and very likely to suffer context switches. | + +It is up to the derivations' build script to respect host's requested +cores-per-build by following the value of the `NIX_BUILD_CORES` +environment variable. diff --git a/doc/manual/src/advanced-topics/diff-hook.md b/doc/manual/src/advanced-topics/diff-hook.md new file mode 100644 index 000000000..7a2622b3d --- /dev/null +++ b/doc/manual/src/advanced-topics/diff-hook.md @@ -0,0 +1,157 @@ +# Verifying Build Reproducibility + +You can use Nix's `diff-hook` setting to compare build results. Note +that this hook is only executed if the results differ; it is not used +for determining if the results are the same. + +For purposes of demonstration, we'll use the following Nix file, +`deterministic.nix` for testing: + +```nix +let + inherit (import <nixpkgs> {}) runCommand; +in { + stable = runCommand "stable" {} '' + touch $out + ''; + + unstable = runCommand "unstable" {} '' + echo $RANDOM > $out + ''; +} +``` + +Additionally, `nix.conf` contains: + + diff-hook = /etc/nix/my-diff-hook + run-diff-hook = true + +where `/etc/nix/my-diff-hook` is an executable file containing: + +```bash +#!/bin/sh +exec >&2 +echo "For derivation $3:" +/run/current-system/sw/bin/diff -r "$1" "$2" +``` + +The diff hook is executed by the same user and group who ran the build. +However, the diff hook does not have write access to the store path just +built. + +# Spot-Checking Build Determinism + +Verify a path which already exists in the Nix store by passing `--check` +to the build command. + +If the build passes and is deterministic, Nix will exit with a status +code of 0: + +```console +$ nix-build ./deterministic.nix -A stable +this derivation will be built: + /nix/store/z98fasz2jqy9gs0xbvdj939p27jwda38-stable.drv +building '/nix/store/z98fasz2jqy9gs0xbvdj939p27jwda38-stable.drv'... +/nix/store/yyxlzw3vqaas7wfp04g0b1xg51f2czgq-stable + +$ nix-build ./deterministic.nix -A stable --check +checking outputs of '/nix/store/z98fasz2jqy9gs0xbvdj939p27jwda38-stable.drv'... +/nix/store/yyxlzw3vqaas7wfp04g0b1xg51f2czgq-stable +``` + +If the build is not deterministic, Nix will exit with a status code of +1: + +```console +$ nix-build ./deterministic.nix -A unstable +this derivation will be built: + /nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv +building '/nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv'... +/nix/store/krpqk0l9ib0ibi1d2w52z293zw455cap-unstable + +$ nix-build ./deterministic.nix -A unstable --check +checking outputs of '/nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv'... +error: derivation '/nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv' may +not be deterministic: output '/nix/store/krpqk0l9ib0ibi1d2w52z293zw455cap-unstable' differs +``` + +In the Nix daemon's log, we will now see: + +``` +For derivation /nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv: +1c1 +< 8108 +--- +> 30204 +``` + +Using `--check` with `--keep-failed` will cause Nix to keep the second +build's output in a special, `.check` path: + +```console +$ nix-build ./deterministic.nix -A unstable --check --keep-failed +checking outputs of '/nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv'... +note: keeping build directory '/tmp/nix-build-unstable.drv-0' +error: derivation '/nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv' may +not be deterministic: output '/nix/store/krpqk0l9ib0ibi1d2w52z293zw455cap-unstable' differs +from '/nix/store/krpqk0l9ib0ibi1d2w52z293zw455cap-unstable.check' +``` + +In particular, notice the +`/nix/store/krpqk0l9ib0ibi1d2w52z293zw455cap-unstable.check` output. Nix +has copied the build results to that directory where you can examine it. + +> **Note** +> +> Check paths are not protected against garbage collection, and this +> path will be deleted on the next garbage collection. +> +> The path is guaranteed to be alive for the duration of +> the `diff-hook`'s execution, but may be deleted any time after. +> +> If the comparison is performed as part of automated tooling, please +> use the diff-hook or author your tooling to handle the case where the +> build was not deterministic and also a check path does not exist. + +`--check` is only usable if the derivation has been built on the system +already. If the derivation has not been built Nix will fail with the +error: + + error: some outputs of '/nix/store/hzi1h60z2qf0nb85iwnpvrai3j2w7rr6-unstable.drv' + are not valid, so checking is not possible + +Run the build without `--check`, and then try with `--check` again. + +# Automatic and Optionally Enforced Determinism Verification + +Automatically verify every build at build time by executing the build +multiple times. + +Setting `repeat` and `enforce-determinism` in your `nix.conf` permits +the automated verification of every build Nix performs. + +The following configuration will run each build three times, and will +require the build to be deterministic: + + enforce-determinism = true + repeat = 2 + +Setting `enforce-determinism` to false as in the following +configuration will run the build multiple times, execute the build +hook, but will allow the build to succeed even if it does not build +reproducibly: + + enforce-determinism = false + repeat = 1 + +An example output of this configuration: + +```console +$ nix-build ./test.nix -A unstable +this derivation will be built: + /nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv +building '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' (round 1/2)... +building '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' (round 2/2)... +output '/nix/store/6xg356v9gl03hpbbg8gws77n19qanh02-unstable' of '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' differs from '/nix/store/6xg356v9gl03hpbbg8gws77n19qanh02-unstable.check' from previous round +/nix/store/6xg356v9gl03hpbbg8gws77n19qanh02-unstable +``` diff --git a/doc/manual/src/advanced-topics/distributed-builds.md b/doc/manual/src/advanced-topics/distributed-builds.md new file mode 100644 index 000000000..c6966a50b --- /dev/null +++ b/doc/manual/src/advanced-topics/distributed-builds.md @@ -0,0 +1,154 @@ +# Remote Builds + +Nix supports remote builds, where a local Nix installation can forward +Nix builds to other machines. This allows multiple builds to be +performed in parallel and allows Nix to perform multi-platform builds in +a semi-transparent way. For instance, if you perform a build for a +`x86_64-darwin` on an `i686-linux` machine, Nix can automatically +forward the build to a `x86_64-darwin` machine, if available. + +To forward a build to a remote machine, it’s required that the remote +machine is accessible via SSH and that it has Nix installed. You can +test whether connecting to the remote Nix instance works, e.g. + +```console +$ nix ping-store --store ssh://mac +``` + +will try to connect to the machine named `mac`. It is possible to +specify an SSH identity file as part of the remote store URI, e.g. + +```console +$ nix ping-store --store ssh://mac?ssh-key=/home/alice/my-key +``` + +Since builds should be non-interactive, the key should not have a +passphrase. Alternatively, you can load identities ahead of time into +`ssh-agent` or `gpg-agent`. + +If you get the error + +```console +bash: nix-store: command not found +error: cannot connect to 'mac' +``` + +then you need to ensure that the `PATH` of non-interactive login shells +contains Nix. + +> **Warning** +> +> If you are building via the Nix daemon, it is the Nix daemon user +> account (that is, `root`) that should have SSH access to the remote +> machine. If you can’t or don’t want to configure `root` to be able to +> access to remote machine, you can use a private Nix store instead by +> passing e.g. `--store ~/my-nix`. + +The list of remote machines can be specified on the command line or in +the Nix configuration file. The former is convenient for testing. For +example, the following command allows you to build a derivation for +`x86_64-darwin` on a Linux machine: + +```console +$ uname +Linux + +$ nix build \ + '(with import <nixpkgs> { system = "x86_64-darwin"; }; runCommand "foo" {} "uname > $out")' \ + --builders 'ssh://mac x86_64-darwin' +[1/0/1 built, 0.0 MiB DL] building foo on ssh://mac + +$ cat ./result +Darwin +``` + +It is possible to specify multiple builders separated by a semicolon or +a newline, e.g. + +```console + --builders 'ssh://mac x86_64-darwin ; ssh://beastie x86_64-freebsd' +``` + +Each machine specification consists of the following elements, separated +by spaces. Only the first element is required. To leave a field at its +default, set it to `-`. + +1. The URI of the remote store in the format + `ssh://[username@]hostname`, e.g. `ssh://nix@mac` or `ssh://mac`. + For backward compatibility, `ssh://` may be omitted. The hostname + may be an alias defined in your `~/.ssh/config`. + +2. A comma-separated list of Nix platform type identifiers, such as + `x86_64-darwin`. It is possible for a machine to support multiple + platform types, e.g., `i686-linux,x86_64-linux`. If omitted, this + defaults to the local platform type. + +3. The SSH identity file to be used to log in to the remote machine. If + omitted, SSH will use its regular identities. + +4. The maximum number of builds that Nix will execute in parallel on + the machine. Typically this should be equal to the number of CPU + cores. For instance, the machine `itchy` in the example will execute + up to 8 builds in parallel. + +5. The “speed factor”, indicating the relative speed of the machine. If + there are multiple machines of the right type, Nix will prefer the + fastest, taking load into account. + +6. A comma-separated list of *supported features*. If a derivation has + the `requiredSystemFeatures` attribute, then Nix will only perform + the derivation on a machine that has the specified features. For + instance, the attribute + + ```nix + requiredSystemFeatures = [ "kvm" ]; + ``` + + will cause the build to be performed on a machine that has the `kvm` + feature. + +7. A comma-separated list of *mandatory features*. A machine will only + be used to build a derivation if all of the machine’s mandatory + features appear in the derivation’s `requiredSystemFeatures` + attribute.. + +For example, the machine specification + + nix@scratchy.labs.cs.uu.nl i686-linux /home/nix/.ssh/id_scratchy_auto 8 1 kvm + nix@itchy.labs.cs.uu.nl i686-linux /home/nix/.ssh/id_scratchy_auto 8 2 + nix@poochie.labs.cs.uu.nl i686-linux /home/nix/.ssh/id_scratchy_auto 1 2 kvm benchmark + +specifies several machines that can perform `i686-linux` builds. +However, `poochie` will only do builds that have the attribute + +```nix +requiredSystemFeatures = [ "benchmark" ]; +``` + +or + +```nix +requiredSystemFeatures = [ "benchmark" "kvm" ]; +``` + +`itchy` cannot do builds that require `kvm`, but `scratchy` does support +such builds. For regular builds, `itchy` will be preferred over +`scratchy` because it has a higher speed factor. + +Remote builders can also be configured in `nix.conf`, e.g. + + builders = ssh://mac x86_64-darwin ; ssh://beastie x86_64-freebsd + +Finally, remote builders can be configured in a separate configuration +file included in `builders` via the syntax `@file`. For example, + + builders = @/etc/nix/machines + +causes the list of machines in `/etc/nix/machines` to be included. (This +is the default.) + +If you want the builders to use caches, you likely want to set the +option `builders-use-substitutes` in your local `nix.conf`. + +To build only on remote builders and disable building on the local +machine, you can use the option `--max-jobs 0`. diff --git a/doc/manual/src/advanced-topics/post-build-hook.md b/doc/manual/src/advanced-topics/post-build-hook.md new file mode 100644 index 000000000..bbdabed41 --- /dev/null +++ b/doc/manual/src/advanced-topics/post-build-hook.md @@ -0,0 +1,123 @@ +# Using the `post-build-hook` + +# Implementation Caveats + +Here we use the post-build hook to upload to a binary cache. This is a +simple and working example, but it is not suitable for all use cases. + +The post build hook program runs after each executed build, and blocks +the build loop. The build loop exits if the hook program fails. + +Concretely, this implementation will make Nix slow or unusable when the +internet is slow or unreliable. + +A more advanced implementation might pass the store paths to a +user-supplied daemon or queue for processing the store paths outside of +the build loop. + +# Prerequisites + +This tutorial assumes you have [configured an S3-compatible binary +cache](../package-management/s3-substituter.md), and that the `root` +user's default AWS profile can upload to the bucket. + +# Set up a Signing Key + +Use `nix-store --generate-binary-cache-key` to create our public and +private signing keys. We will sign paths with the private key, and +distribute the public key for verifying the authenticity of the paths. + +```console +# nix-store --generate-binary-cache-key example-nix-cache-1 /etc/nix/key.private /etc/nix/key.public +# cat /etc/nix/key.public +example-nix-cache-1:1/cKDz3QCCOmwcztD2eV6Coggp6rqc9DGjWv7C0G+rM= +``` + +Then, add the public key and the cache URL to your `nix.conf`'s +`trusted-public-keys` and `substituters` options: + + substituters = https://cache.nixos.org/ s3://example-nix-cache + trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= example-nix-cache-1:1/cKDz3QCCOmwcztD2eV6Coggp6rqc9DGjWv7C0G+rM= + +We will restart the Nix daemon in a later step. + +# Implementing the build hook + +Write the following script to `/etc/nix/upload-to-cache.sh`: + +```bash +#!/bin/sh + +set -eu +set -f # disable globbing +export IFS=' ' + +echo "Signing paths" $OUT_PATHS +nix sign-paths --key-file /etc/nix/key.private $OUT_PATHS +echo "Uploading paths" $OUT_PATHS +exec nix copy --to 's3://example-nix-cache' $OUT_PATHS +``` + +> **Note** +> +> The `$OUT_PATHS` variable is a space-separated list of Nix store +> paths. In this case, we expect and want the shell to perform word +> splitting to make each output path its own argument to `nix +> sign-paths`. Nix guarantees the paths will not contain any spaces, +> however a store path might contain glob characters. The `set -f` +> disables globbing in the shell. + +Then make sure the hook program is executable by the `root` user: + +```console +# chmod +x /etc/nix/upload-to-cache.sh +``` + +# Updating Nix Configuration + +Edit `/etc/nix/nix.conf` to run our hook, by adding the following +configuration snippet at the end: + + post-build-hook = /etc/nix/upload-to-cache.sh + +Then, restart the `nix-daemon`. + +# Testing + +Build any derivation, for example: + +```console +$ nix-build -E '(import <nixpkgs> {}).writeText "example" (builtins.toString builtins.currentTime)' +this derivation will be built: + /nix/store/s4pnfbkalzy5qz57qs6yybna8wylkig6-example.drv +building '/nix/store/s4pnfbkalzy5qz57qs6yybna8wylkig6-example.drv'... +running post-build-hook '/home/grahamc/projects/github.com/NixOS/nix/post-hook.sh'... +post-build-hook: Signing paths /nix/store/ibcyipq5gf91838ldx40mjsp0b8w9n18-example +post-build-hook: Uploading paths /nix/store/ibcyipq5gf91838ldx40mjsp0b8w9n18-example +/nix/store/ibcyipq5gf91838ldx40mjsp0b8w9n18-example +``` + +Then delete the path from the store, and try substituting it from the +binary cache: + +```console +$ rm ./result +$ nix-store --delete /nix/store/ibcyipq5gf91838ldx40mjsp0b8w9n18-example +``` + +Now, copy the path back from the cache: + +```console +$ nix-store --realise /nix/store/ibcyipq5gf91838ldx40mjsp0b8w9n18-example +copying path '/nix/store/m8bmqwrch6l3h8s0k3d673xpmipcdpsa-example from 's3://example-nix-cache'... +warning: you did not specify '--add-root'; the result might be removed by the garbage collector +/nix/store/m8bmqwrch6l3h8s0k3d673xpmipcdpsa-example +``` + +# Conclusion + +We now have a Nix installation configured to automatically sign and +upload every local build to a remote binary cache. + +Before deploying this to production, be sure to consider the +[implementation caveats](#implementation-caveats). diff --git a/doc/manual/src/command-ref/command-ref.md b/doc/manual/src/command-ref/command-ref.md new file mode 100644 index 000000000..6a78075db --- /dev/null +++ b/doc/manual/src/command-ref/command-ref.md @@ -0,0 +1,2 @@ +This section lists commands and options that you can use when you work +with Nix. diff --git a/doc/manual/src/command-ref/conf-file-prefix.md b/doc/manual/src/command-ref/conf-file-prefix.md new file mode 100644 index 000000000..04c6cd859 --- /dev/null +++ b/doc/manual/src/command-ref/conf-file-prefix.md @@ -0,0 +1,39 @@ +Title: nix.conf + +# Name + +`nix.conf` - Nix configuration file + +# Description + +By default Nix reads settings from the following places: + + - The system-wide configuration file `sysconfdir/nix/nix.conf` (i.e. + `/etc/nix/nix.conf` on most systems), or `$NIX_CONF_DIR/nix.conf` if + `NIX_CONF_DIR` is set. Values loaded in this file are not forwarded + to the Nix daemon. The client assumes that the daemon has already + loaded them. + + - If `NIX_USER_CONF_FILES` is set, then each path separated by `:` + will be loaded in reverse order. + + Otherwise it will look for `nix/nix.conf` files in `XDG_CONFIG_DIRS` + and `XDG_CONFIG_HOME`. If these are unset, it will look in + `$HOME/.config/nix.conf`. + +The configuration files consist of `name = +value` pairs, one per line. Other files can be included with a line like +`include +path`, where *path* is interpreted relative to the current conf file and +a missing file is an error unless `!include` is used instead. Comments +start with a `#` character. Here is an example configuration file: + + keep-outputs = true # Nice for developers + keep-derivations = true # Idem + +You can override settings on the command line using the `--option` flag, +e.g. `--option keep-outputs +false`. + +The following settings are currently available: + diff --git a/doc/manual/src/command-ref/env-common.md b/doc/manual/src/command-ref/env-common.md new file mode 100644 index 000000000..03016dba7 --- /dev/null +++ b/doc/manual/src/command-ref/env-common.md @@ -0,0 +1,115 @@ +# Common Environment Variables + +Most Nix commands interpret the following environment variables: + + - `IN_NIX_SHELL` + Indicator that tells if the current environment was set up by + `nix-shell`. Since Nix 2.0 the values are `"pure"` and `"impure"` + + - `NIX_PATH` + A colon-separated list of directories used to look up Nix + expressions enclosed in angle brackets (i.e., `<path>`). For + instance, the value + + /home/eelco/Dev:/etc/nixos + + will cause Nix to look for paths relative to `/home/eelco/Dev` and + `/etc/nixos`, in this order. It is also possible to match paths + against a prefix. For example, the value + + nixpkgs=/home/eelco/Dev/nixpkgs-branch:/etc/nixos + + will cause Nix to search for `<nixpkgs/path>` in + `/home/eelco/Dev/nixpkgs-branch/path` and `/etc/nixos/nixpkgs/path`. + + If a path in the Nix search path starts with `http://` or + `https://`, it is interpreted as the URL of a tarball that will be + downloaded and unpacked to a temporary location. The tarball must + consist of a single top-level directory. For example, setting + `NIX_PATH` to + + nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixos-15.09.tar.gz + + tells Nix to download the latest revision in the Nixpkgs/NixOS 15.09 + channel. + + A following shorthand can be used to refer to the official channels: + + nixpkgs=channel:nixos-15.09 + + The search path can be extended using the `-I` option, which takes + precedence over `NIX_PATH`. + + - `NIX_IGNORE_SYMLINK_STORE` + Normally, the Nix store directory (typically `/nix/store`) is not + allowed to contain any symlink components. This is to prevent + “impure” builds. Builders sometimes “canonicalise” paths by + resolving all symlink components. Thus, builds on different machines + (with `/nix/store` resolving to different locations) could yield + different results. This is generally not a problem, except when + builds are deployed to machines where `/nix/store` resolves + differently. If you are sure that you’re not going to do that, you + can set `NIX_IGNORE_SYMLINK_STORE` to `1`. + + Note that if you’re symlinking the Nix store so that you can put it + on another file system than the root file system, on Linux you’re + better off using `bind` mount points, e.g., + + ```console + $ mkdir /nix + $ mount -o bind /mnt/otherdisk/nix /nix + ``` + + Consult the mount 8 manual page for details. + + - `NIX_STORE_DIR` + Overrides the location of the Nix store (default `prefix/store`). + + - `NIX_DATA_DIR` + Overrides the location of the Nix static data directory (default + `prefix/share`). + + - `NIX_LOG_DIR` + Overrides the location of the Nix log directory (default + `prefix/var/log/nix`). + + - `NIX_STATE_DIR` + Overrides the location of the Nix state directory (default + `prefix/var/nix`). + + - `NIX_CONF_DIR` + Overrides the location of the system Nix configuration directory + (default `prefix/etc/nix`). + + - `NIX_USER_CONF_FILES` + Overrides the location of the user Nix configuration files to load + from (defaults to the XDG spec locations). The variable is treated + as a list separated by the `:` token. + + - `TMPDIR` + Use the specified directory to store temporary files. In particular, + this includes temporary build directories; these can take up + substantial amounts of disk space. The default is `/tmp`. + + - `NIX_REMOTE` + This variable should be set to `daemon` if you want to use the Nix + daemon to execute Nix operations. This is necessary in [multi-user + Nix installations](../installation/multi-user.md). If the Nix + daemon's Unix socket is at some non-standard path, this variable + should be set to `unix://path/to/socket`. Otherwise, it should be + left unset. + + - `NIX_SHOW_STATS` + If set to `1`, Nix will print some evaluation statistics, such as + the number of values allocated. + + - `NIX_COUNT_CALLS` + If set to `1`, Nix will print how often functions were called during + Nix expression evaluation. This is useful for profiling your Nix + expressions. + + - `GC_INITIAL_HEAP_SIZE` + If Nix has been configured to use the Boehm garbage collector, this + variable sets the initial size of the heap in bytes. It defaults to + 384 MiB. Setting it to a low value reduces memory consumption, but + will increase runtime due to the overhead of garbage collection. diff --git a/doc/manual/src/command-ref/experimental-commands.md b/doc/manual/src/command-ref/experimental-commands.md new file mode 100644 index 000000000..cfa6f8b73 --- /dev/null +++ b/doc/manual/src/command-ref/experimental-commands.md @@ -0,0 +1,8 @@ +# Experimental Commands + +This section lists experimental commands. + +> **Warning** +> +> These commands may be removed in the future, or their syntax may +> change in incompatible ways. diff --git a/doc/manual/src/command-ref/files.md b/doc/manual/src/command-ref/files.md new file mode 100644 index 000000000..df5646c05 --- /dev/null +++ b/doc/manual/src/command-ref/files.md @@ -0,0 +1,4 @@ +# Files + +This section lists configuration files that you can use when you work +with Nix. diff --git a/doc/manual/src/command-ref/main-commands.md b/doc/manual/src/command-ref/main-commands.md new file mode 100644 index 000000000..e4f1f1d0e --- /dev/null +++ b/doc/manual/src/command-ref/main-commands.md @@ -0,0 +1,4 @@ +# Main Commands + +This section lists commands and options that you can use when you work +with Nix. diff --git a/doc/manual/src/command-ref/nix-build.md b/doc/manual/src/command-ref/nix-build.md new file mode 100644 index 000000000..4bcb8db40 --- /dev/null +++ b/doc/manual/src/command-ref/nix-build.md @@ -0,0 +1,113 @@ +Title: nix-build + +# Name + +`nix-build` - build a Nix expression + +# Synopsis + +`nix-build` [*paths…*] + [`--arg` *name* *value*] + [`--argstr` *name* *value*] + [{`--attr` | `-A`} *attrPath*] + [`--no-out-link`] + [`--dry-run`] + [{`--out-link` | `-o`} *outlink*] + +# Description + +The `nix-build` command builds the derivations described by the Nix +expressions in *paths*. If the build succeeds, it places a symlink to +the result in the current directory. The symlink is called `result`. If +there are multiple Nix expressions, or the Nix expressions evaluate to +multiple derivations, multiple sequentially numbered symlinks are +created (`result`, `result-2`, and so on). + +If no *paths* are specified, then `nix-build` will use `default.nix` in +the current directory, if it exists. + +If an element of *paths* starts with `http://` or `https://`, it is +interpreted as the URL of a tarball that will be downloaded and unpacked +to a temporary location. The tarball must include a single top-level +directory containing at least a file named `default.nix`. + +`nix-build` is essentially a wrapper around +[`nix-instantiate`](nix-instantiate.md) (to translate a high-level Nix +expression to a low-level store derivation) and [`nix-store +--realise`](nix-store.md#operation---realise) (to build the store +derivation). + +> **Warning** +> +> The result of the build is automatically registered as a root of the +> Nix garbage collector. This root disappears automatically when the +> `result` symlink is deleted or renamed. So don’t rename the symlink. + +# Options + +All options not listed here are passed to `nix-store +--realise`, except for `--arg` and `--attr` / `-A` which are passed to +`nix-instantiate`. + + - `--no-out-link` + Do not create a symlink to the output path. Note that as a result + the output does not become a root of the garbage collector, and so + might be deleted by `nix-store + --gc`. + + - `--dry-run` + Show what store paths would be built or downloaded. + + - `--out-link` / `-o` *outlink* + Change the name of the symlink to the output path created from + `result` to *outlink*. + +The following common options are supported: + +# Examples + +```console +$ nix-build '<nixpkgs>' -A firefox +store derivation is /nix/store/qybprl8sz2lc...-firefox-1.5.0.7.drv +/nix/store/d18hyl92g30l...-firefox-1.5.0.7 + +$ ls -l result +lrwxrwxrwx ... result -> /nix/store/d18hyl92g30l...-firefox-1.5.0.7 + +$ ls ./result/bin/ +firefox firefox-config +``` + +If a derivation has multiple outputs, `nix-build` will build the default +(first) output. You can also build all outputs: + +```console +$ nix-build '<nixpkgs>' -A openssl.all +``` + +This will create a symlink for each output named `result-outputname`. +The suffix is omitted if the output name is `out`. So if `openssl` has +outputs `out`, `bin` and `man`, `nix-build` will create symlinks +`result`, `result-bin` and `result-man`. It’s also possible to build a +specific output: + +```console +$ nix-build '<nixpkgs>' -A openssl.man +``` + +This will create a symlink `result-man`. + +Build a Nix expression given on the command line: + +```console +$ nix-build -E 'with import <nixpkgs> { }; runCommand "foo" { } "echo bar > $out"' +$ cat ./result +bar +``` + +Build the GNU Hello package from the latest revision of the master +branch of Nixpkgs: + +```console +$ nix-build https://github.com/NixOS/nixpkgs/archive/master.tar.gz -A hello +``` diff --git a/doc/manual/src/command-ref/nix-channel.md b/doc/manual/src/command-ref/nix-channel.md new file mode 100644 index 000000000..f0e205967 --- /dev/null +++ b/doc/manual/src/command-ref/nix-channel.md @@ -0,0 +1,98 @@ +Title: nix-channel + +# Name + +`nix-channel` - manage Nix channels + +# Synopsis + +`nix-channel` {`--add` url [*name*] | `--remove` *name* | `--list` | `--update` [*names…*] | `--rollback` [*generation*] } + +# Description + +A Nix channel is a mechanism that allows you to automatically stay +up-to-date with a set of pre-built Nix expressions. A Nix channel is +just a URL that points to a place containing a set of Nix expressions. + +To see the list of official NixOS channels, visit +<https://nixos.org/channels>. + +This command has the following operations: + + - `--add` *url* \[*name*\] + Adds a channel named *name* with URL *url* to the list of subscribed + channels. If *name* is omitted, it defaults to the last component of + *url*, with the suffixes `-stable` or `-unstable` removed. + + - `--remove` *name* + Removes the channel named *name* from the list of subscribed + channels. + + - `--list` + Prints the names and URLs of all subscribed channels on standard + output. + + - `--update` \[*names*…\] + Downloads the Nix expressions of all subscribed channels (or only + those included in *names* if specified) and makes them the default + for `nix-env` operations (by symlinking them from the directory + `~/.nix-defexpr`). + + - `--rollback` \[*generation*\] + Reverts the previous call to `nix-channel + --update`. Optionally, you can specify a specific channel generation + number to restore. + +Note that `--add` does not automatically perform an update. + +The list of subscribed channels is stored in `~/.nix-channels`. + +# Examples + +To subscribe to the Nixpkgs channel and install the GNU Hello package: + +```console +$ nix-channel --add https://nixos.org/channels/nixpkgs-unstable +$ nix-channel --update +$ nix-env -iA nixpkgs.hello +``` + +You can revert channel updates using `--rollback`: + +```console +$ nix-instantiate --eval -E '(import <nixpkgs> {}).lib.version' +"14.04.527.0e935f1" + +$ nix-channel --rollback +switching from generation 483 to 482 + +$ nix-instantiate --eval -E '(import <nixpkgs> {}).lib.version' +"14.04.526.dbadfad" +``` + +# Files + + - `/nix/var/nix/profiles/per-user/username/channels` + `nix-channel` uses a `nix-env` profile to keep track of previous + versions of the subscribed channels. Every time you run `nix-channel + --update`, a new channel generation (that is, a symlink to the + channel Nix expressions in the Nix store) is created. This enables + `nix-channel --rollback` to revert to previous versions. + + - `~/.nix-defexpr/channels` + This is a symlink to + `/nix/var/nix/profiles/per-user/username/channels`. It ensures that + `nix-env` can find your channels. In a multi-user installation, you + may also have `~/.nix-defexpr/channels_root`, which links to the + channels of the root user. + +# Channel format + +A channel URL should point to a directory containing the following +files: + + - `nixexprs.tar.xz` + A tarball containing Nix expressions and files referenced by them + (such as build scripts and patches). At the top level, the tarball + should contain a single directory. That directory must contain a + file `default.nix` that serves as the channel’s “entry point”. diff --git a/doc/manual/src/command-ref/nix-collect-garbage.md b/doc/manual/src/command-ref/nix-collect-garbage.md new file mode 100644 index 000000000..62a6b7ca0 --- /dev/null +++ b/doc/manual/src/command-ref/nix-collect-garbage.md @@ -0,0 +1,32 @@ +Title: nix-collect-garbage + +# Name + +`nix-collect-garbage` - delete unreachable store paths + +# Synopsis + +`nix-collect-garbage` [`--delete-old`] [`-d`] [`--delete-older-than` *period*] [`--max-freed` *bytes*] [`--dry-run`] + +# Description + +The command `nix-collect-garbage` is mostly an alias of [`nix-store +--gc`](nix-store.md#operation---gc), that is, it deletes all +unreachable paths in the Nix store to clean up your system. However, +it provides two additional options: `-d` (`--delete-old`), which +deletes all old generations of all profiles in `/nix/var/nix/profiles` +by invoking `nix-env --delete-generations old` on all profiles (of +course, this makes rollbacks to previous configurations impossible); +and `--delete-older-than` *period*, where period is a value such as +`30d`, which deletes all generations older than the specified number +of days in all profiles in `/nix/var/nix/profiles` (except for the +generations that were active at that point in time). + +# Example + +To delete from the Nix store everything that is not used by the current +generations of each profile, do + +```console +$ nix-collect-garbage -d +``` diff --git a/doc/manual/src/command-ref/nix-copy-closure.md b/doc/manual/src/command-ref/nix-copy-closure.md new file mode 100644 index 000000000..5ce320af7 --- /dev/null +++ b/doc/manual/src/command-ref/nix-copy-closure.md @@ -0,0 +1,87 @@ +Title: nix-copy-closure + +# Name + +`nix-copy-closure` - copy a closure to or from a remote machine via SSH + +# Synopsis + +`nix-copy-closure` + [`--to` | `--from`] + [`--gzip`] + [`--include-outputs`] + [`--use-substitutes` | `-s`] + [`-v`] + _user@machine_ _paths_ + +# Description + +`nix-copy-closure` gives you an easy and efficient way to exchange +software between machines. Given one or more Nix store _paths_ on the +local machine, `nix-copy-closure` computes the closure of those paths +(i.e. all their dependencies in the Nix store), and copies all paths +in the closure to the remote machine via the `ssh` (Secure Shell) +command. With the `--from` option, the direction is reversed: the +closure of _paths_ on a remote machine is copied to the Nix store on +the local machine. + +This command is efficient because it only sends the store paths +that are missing on the target machine. + +Since `nix-copy-closure` calls `ssh`, you may be asked to type in the +appropriate password or passphrase. In fact, you may be asked _twice_ +because `nix-copy-closure` currently connects twice to the remote +machine, first to get the set of paths missing on the target machine, +and second to send the dump of those paths. If this bothers you, use +`ssh-agent`. + +# Options + + - `--to` + Copy the closure of _paths_ from the local Nix store to the Nix + store on _machine_. This is the default. + + - `--from` + Copy the closure of _paths_ from the Nix store on _machine_ to the + local Nix store. + + - `--gzip` + Enable compression of the SSH connection. + + - `--include-outputs` + Also copy the outputs of store derivations included in the closure. + + - `--use-substitutes` / `-s` + Attempt to download missing paths on the target machine using Nix’s + substitute mechanism. Any paths that cannot be substituted on the + target are still copied normally from the source. This is useful, + for instance, if the connection between the source and target + machine is slow, but the connection between the target machine and + `nixos.org` (the default binary cache server) is + fast. + + - `-v` + Show verbose output. + +# Environment variables + + - `NIX_SSHOPTS` + Additional options to be passed to `ssh` on the command + line. + +# Examples + +Copy Firefox with all its dependencies to a remote machine: + +```console +$ nix-copy-closure --to alice@itchy.labs $(type -tP firefox) +``` + +Copy Subversion from a remote machine and then install it into a user +environment: + +```console +$ nix-copy-closure --from alice@itchy.labs \ + /nix/store/0dj0503hjxy5mbwlafv1rsbdiyx1gkdy-subversion-1.4.4 +$ nix-env -i /nix/store/0dj0503hjxy5mbwlafv1rsbdiyx1gkdy-subversion-1.4.4 +``` diff --git a/doc/manual/src/command-ref/nix-daemon.md b/doc/manual/src/command-ref/nix-daemon.md new file mode 100644 index 000000000..bd5d25026 --- /dev/null +++ b/doc/manual/src/command-ref/nix-daemon.md @@ -0,0 +1,15 @@ +Title: nix-daemon + +# Name + +`nix-daemon` - Nix multi-user support daemon + +# Synopsis + +`nix-daemon` + +# Description + +The Nix daemon is necessary in multi-user Nix installations. It performs +build actions and other operations on the Nix store on behalf of +unprivileged users. diff --git a/doc/manual/src/command-ref/nix-env.md b/doc/manual/src/command-ref/nix-env.md new file mode 100644 index 000000000..ee838581b --- /dev/null +++ b/doc/manual/src/command-ref/nix-env.md @@ -0,0 +1,882 @@ +Title: nix-env + +# Name + +`nix-env` - manipulate or query Nix user environments + +# Synopsis + +`nix-env` + [`--option` *name* *value*] + [`--arg` *name* *value*] + [`--argstr` *name* *value*] + [{`--file` | `-f`} *path*] + [{`--profile` | `-p`} *path(] + [`--system-filter` *system*] + [`--dry-run`] + *operation* [*options…*] [*arguments…*] + +# Description + +The command `nix-env` is used to manipulate Nix user environments. User +environments are sets of software packages available to a user at some +point in time. In other words, they are a synthesised view of the +programs available in the Nix store. There may be many user +environments: different users can have different environments, and +individual users can switch between different environments. + +`nix-env` takes exactly one *operation* flag which indicates the +subcommand to be performed. These are documented below. + +# Selectors + +Several commands, such as `nix-env -q` and `nix-env -i`, take a list of +arguments that specify the packages on which to operate. These are +extended regular expressions that must match the entire name of the +package. (For details on regular expressions, see regex7.) The match is +case-sensitive. The regular expression can optionally be followed by a +dash and a version number; if omitted, any version of the package will +match. Here are some examples: + + - `firefox` + Matches the package name `firefox` and any version. + + - `firefox-32.0` + Matches the package name `firefox` and version `32.0`. + + - `gtk\\+` + Matches the package name `gtk+`. The `+` character must be escaped + using a backslash to prevent it from being interpreted as a + quantifier, and the backslash must be escaped in turn with another + backslash to ensure that the shell passes it on. + + - `.\*` + Matches any package name. This is the default for most commands. + + - `'.*zip.*'` + Matches any package name containing the string `zip`. Note the dots: + `'*zip*'` does not work, because in a regular expression, the + character `*` is interpreted as a quantifier. + + - `'.*(firefox|chromium).*'` + Matches any package name containing the strings `firefox` or + `chromium`. + +# Common options + +This section lists the options that are common to all operations. These +options are allowed for every subcommand, though they may not always +have an effect. + + - `--file` / `-f` *path* + Specifies the Nix expression (designated below as the *active Nix + expression*) used by the `--install`, `--upgrade`, and `--query + --available` operations to obtain derivations. The default is + `~/.nix-defexpr`. + + If the argument starts with `http://` or `https://`, it is + interpreted as the URL of a tarball that will be downloaded and + unpacked to a temporary location. The tarball must include a single + top-level directory containing at least a file named `default.nix`. + + - `--profile` / `-p` *path* + Specifies the profile to be used by those operations that operate on + a profile (designated below as the *active profile*). A profile is a + sequence of user environments called *generations*, one of which is + the *current generation*. + + - `--dry-run` + For the `--install`, `--upgrade`, `--uninstall`, + `--switch-generation`, `--delete-generations` and `--rollback` + operations, this flag will cause `nix-env` to print what *would* be + done if this flag had not been specified, without actually doing it. + + `--dry-run` also prints out which paths will be + [substituted](../glossary.md) (i.e., downloaded) and which paths + will be built from source (because no substitute is available). + + - `--system-filter` *system* + By default, operations such as `--query + --available` show derivations matching any platform. This option + allows you to use derivations for the specified platform *system*. + +<!-- end list --> + +# Files + + - `~/.nix-defexpr` + The source for the default Nix expressions used by the + `--install`, `--upgrade`, and `--query --available` operations to + obtain derivations. The `--file` option may be used to override + this default. + + If `~/.nix-defexpr` is a file, it is loaded as a Nix expression. If + the expression is a set, it is used as the default Nix expression. + If the expression is a function, an empty set is passed as argument + and the return value is used as the default Nix expression. + + If `~/.nix-defexpr` is a directory containing a `default.nix` file, + that file is loaded as in the above paragraph. + + If `~/.nix-defexpr` is a directory without a `default.nix` file, + then its contents (both files and subdirectories) are loaded as Nix + expressions. The expressions are combined into a single set, each + expression under an attribute with the same name as the original + file or subdirectory. + + For example, if `~/.nix-defexpr` contains two files, `foo.nix` and + `bar.nix`, then the default Nix expression will essentially be + + ```nix + { + foo = import ~/.nix-defexpr/foo.nix; + bar = import ~/.nix-defexpr/bar.nix; + } + ``` + + The file `manifest.nix` is always ignored. Subdirectories without a + `default.nix` file are traversed recursively in search of more Nix + expressions, but the names of these intermediate directories are not + added to the attribute paths of the default Nix expression. + + The command `nix-channel` places symlinks to the downloaded Nix + expressions from each subscribed channel in this directory. + + - `~/.nix-profile` + A symbolic link to the user's current profile. By default, this + symlink points to `prefix/var/nix/profiles/default`. The `PATH` + environment variable should include `~/.nix-profile/bin` for the + user environment to be visible to the user. + +# Operation `--install` + +## Synopsis + +`nix-env` {`--install` | `-i`} *args…* + [{`--prebuilt-only` | `-b`}] + [{`--attr` | `-A`}] + [`--from-expression`] [`-E`] + [`--from-profile` *path*] + [`--preserve-installed` | `-P`] + [`--remove-all` | `-r`] + +## Description + +The install operation creates a new user environment, based on the +current generation of the active profile, to which a set of store paths +described by *args* is added. The arguments *args* map to store paths in +a number of possible ways: + + - By default, *args* is a set of derivation names denoting derivations + in the active Nix expression. These are realised, and the resulting + output paths are installed. Currently installed derivations with a + name equal to the name of a derivation being added are removed + unless the option `--preserve-installed` is specified. + + If there are multiple derivations matching a name in *args* that + have the same name (e.g., `gcc-3.3.6` and `gcc-4.1.1`), then the + derivation with the highest *priority* is used. A derivation can + define a priority by declaring the `meta.priority` attribute. This + attribute should be a number, with a higher value denoting a lower + priority. The default priority is `0`. + + If there are multiple matching derivations with the same priority, + then the derivation with the highest version will be installed. + + You can force the installation of multiple derivations with the same + name by being specific about the versions. For instance, `nix-env -i + gcc-3.3.6 gcc-4.1.1` will install both version of GCC (and will + probably cause a user environment conflict\!). + + - If `--attr` (`-A`) is specified, the arguments are *attribute + paths* that select attributes from the top-level Nix + expression. This is faster than using derivation names and + unambiguous. To find out the attribute paths of available + packages, use `nix-env -qaP`. + + - If `--from-profile` *path* is given, *args* is a set of names + denoting installed store paths in the profile *path*. This is an + easy way to copy user environment elements from one profile to + another. + + - If `--from-expression` is given, *args* are Nix + [functions](../expressions/language-constructs.md#functions) + that are called with the active Nix expression as their single + argument. The derivations returned by those function calls are + installed. This allows derivations to be specified in an + unambiguous way, which is necessary if there are multiple + derivations with the same name. + + - If *args* are store derivations, then these are + [realised](nix-store.md#operation---realise), and the resulting output paths + are installed. + + - If *args* are store paths that are not store derivations, then these + are [realised](nix-store.md#operation---realise) and installed. + + - By default all outputs are installed for each derivation. That can + be reduced by setting `meta.outputsToInstall`. + +## Flags + + - `--prebuilt-only` / `-b` + Use only derivations for which a substitute is registered, i.e., + there is a pre-built binary available that can be downloaded in lieu + of building the derivation. Thus, no packages will be built from + source. + + - `--preserve-installed`; `-P` + Do not remove derivations with a name matching one of the + derivations being installed. Usually, trying to have two versions of + the same package installed in the same generation of a profile will + lead to an error in building the generation, due to file name + clashes between the two versions. However, this is not the case for + all packages. + + - `--remove-all`; `-r` + Remove all previously installed packages first. This is equivalent + to running `nix-env -e '.*'` first, except that everything happens + in a single transaction. + +## Examples + +To install a specific version of `gcc` from the active Nix expression: + +```console +$ nix-env --install gcc-3.3.2 +installing `gcc-3.3.2' +uninstalling `gcc-3.1' +``` + +Note the previously installed version is removed, since +`--preserve-installed` was not specified. + +To install an arbitrary version: + +```console +$ nix-env --install gcc +installing `gcc-3.3.2' +``` + +To install using a specific attribute: + +```console +$ nix-env -i -A gcc40mips +$ nix-env -i -A xorg.xorgserver +``` + +To install all derivations in the Nix expression `foo.nix`: + +```console +$ nix-env -f ~/foo.nix -i '.*' +``` + +To copy the store path with symbolic name `gcc` from another profile: + +```console +$ nix-env -i --from-profile /nix/var/nix/profiles/foo gcc +``` + +To install a specific store derivation (typically created by +`nix-instantiate`): + +```console +$ nix-env -i /nix/store/fibjb1bfbpm5mrsxc4mh2d8n37sxh91i-gcc-3.4.3.drv +``` + +To install a specific output path: + +```console +$ nix-env -i /nix/store/y3cgx0xj1p4iv9x0pnnmdhr8iyg741vk-gcc-3.4.3 +``` + +To install from a Nix expression specified on the command-line: + +```console +$ nix-env -f ./foo.nix -i -E \ + 'f: (f {system = "i686-linux";}).subversionWithJava' +``` + +I.e., this evaluates to `(f: (f {system = +"i686-linux";}).subversionWithJava) (import ./foo.nix)`, thus selecting +the `subversionWithJava` attribute from the set returned by calling the +function defined in `./foo.nix`. + +A dry-run tells you which paths will be downloaded or built from source: + +```console +$ nix-env -f '<nixpkgs>' -iA hello --dry-run +(dry run; not doing anything) +installing ‘hello-2.10’ +this path will be fetched (0.04 MiB download, 0.19 MiB unpacked): + /nix/store/wkhdf9jinag5750mqlax6z2zbwhqb76n-hello-2.10 + ... +``` + +To install Firefox from the latest revision in the Nixpkgs/NixOS 14.12 +channel: + +```console +$ nix-env -f https://github.com/NixOS/nixpkgs/archive/nixos-14.12.tar.gz -iA firefox +``` + +# Operation `--upgrade` + +## Synopsis + +`nix-env` {`--upgrade` | `-u`} *args* + [`--lt` | `--leq` | `--eq` | `--always`] + [{`--prebuilt-only` | `-b`}] + [{`--attr` | `-A`}] + [`--from-expression`] [`-E`] + [`--from-profile` *path*] + [`--preserve-installed` | `-P`] + +## Description + +The upgrade operation creates a new user environment, based on the +current generation of the active profile, in which all store paths are +replaced for which there are newer versions in the set of paths +described by *args*. Paths for which there are no newer versions are +left untouched; this is not an error. It is also not an error if an +element of *args* matches no installed derivations. + +For a description of how *args* is mapped to a set of store paths, see +[`--install`](#operation---install). If *args* describes multiple +store paths with the same symbolic name, only the one with the highest +version is installed. + +## Flags + + - `--lt` + Only upgrade a derivation to newer versions. This is the default. + + - `--leq` + In addition to upgrading to newer versions, also “upgrade” to + derivations that have the same version. Version are not a unique + identification of a derivation, so there may be many derivations + that have the same version. This flag may be useful to force + “synchronisation” between the installed and available derivations. + + - `--eq` + *Only* “upgrade” to derivations that have the same version. This may + not seem very useful, but it actually is, e.g., when there is a new + release of Nixpkgs and you want to replace installed applications + with the same versions built against newer dependencies (to reduce + the number of dependencies floating around on your system). + + - `--always` + In addition to upgrading to newer versions, also “upgrade” to + derivations that have the same or a lower version. I.e., derivations + may actually be downgraded depending on what is available in the + active Nix expression. + +For the other flags, see `--install`. + +## Examples + +```console +$ nix-env --upgrade gcc +upgrading `gcc-3.3.1' to `gcc-3.4' +``` + +```console +$ nix-env -u gcc-3.3.2 --always (switch to a specific version) +upgrading `gcc-3.4' to `gcc-3.3.2' +``` + +```console +$ nix-env --upgrade pan +(no upgrades available, so nothing happens) +``` + +```console +$ nix-env -u (try to upgrade everything) +upgrading `hello-2.1.2' to `hello-2.1.3' +upgrading `mozilla-1.2' to `mozilla-1.4' +``` + +## Versions + +The upgrade operation determines whether a derivation `y` is an upgrade +of a derivation `x` by looking at their respective `name` attributes. +The names (e.g., `gcc-3.3.1` are split into two parts: the package name +(`gcc`), and the version (`3.3.1`). The version part starts after the +first dash not followed by a letter. `x` is considered an upgrade of `y` +if their package names match, and the version of `y` is higher that that +of `x`. + +The versions are compared by splitting them into contiguous components +of numbers and letters. E.g., `3.3.1pre5` is split into `[3, 3, 1, +"pre", 5]`. These lists are then compared lexicographically (from left +to right). Corresponding components `a` and `b` are compared as follows. +If they are both numbers, integer comparison is used. If `a` is an empty +string and `b` is a number, `a` is considered less than `b`. The special +string component `pre` (for *pre-release*) is considered to be less than +other components. String components are considered less than number +components. Otherwise, they are compared lexicographically (i.e., using +case-sensitive string comparison). + +This is illustrated by the following examples: + + 1.0 < 2.3 + 2.1 < 2.3 + 2.3 = 2.3 + 2.5 > 2.3 + 3.1 > 2.3 + 2.3.1 > 2.3 + 2.3.1 > 2.3a + 2.3pre1 < 2.3 + 2.3pre3 < 2.3pre12 + 2.3a < 2.3c + 2.3pre1 < 2.3c + 2.3pre1 < 2.3q + +# Operation `--uninstall` + +## Synopsis + +`nix-env` {`--uninstall` | `-e`} *drvnames…* + +## Description + +The uninstall operation creates a new user environment, based on the +current generation of the active profile, from which the store paths +designated by the symbolic names *drvnames* are removed. + +## Examples + +```console +$ nix-env --uninstall gcc +$ nix-env -e '.*' (remove everything) +``` + +# Operation `--set` + +## Synopsis + +`nix-env` `--set` *drvname* + +## Description + +The `--set` operation modifies the current generation of a profile so +that it contains exactly the specified derivation, and nothing else. + +## Examples + +The following updates a profile such that its current generation will +contain just Firefox: + +```console +$ nix-env -p /nix/var/nix/profiles/browser --set firefox +``` + +# Operation `--set-flag` + +## Synopsis + +`nix-env` `--set-flag` *name* *value* *drvnames* + +## Description + +The `--set-flag` operation allows meta attributes of installed packages +to be modified. There are several attributes that can be usefully +modified, because they affect the behaviour of `nix-env` or the user +environment build script: + + - `priority` can be changed to resolve filename clashes. The user + environment build script uses the `meta.priority` attribute of + derivations to resolve filename collisions between packages. Lower + priority values denote a higher priority. For instance, the GCC + wrapper package and the Binutils package in Nixpkgs both have a file + `bin/ld`, so previously if you tried to install both you would get a + collision. Now, on the other hand, the GCC wrapper declares a higher + priority than Binutils, so the former’s `bin/ld` is symlinked in the + user environment. + + - `keep` can be set to `true` to prevent the package from being + upgraded or replaced. This is useful if you want to hang on to an + older version of a package. + + - `active` can be set to `false` to “disable” the package. That is, no + symlinks will be generated to the files of the package, but it + remains part of the profile (so it won’t be garbage-collected). It + can be set back to `true` to re-enable the package. + +## Examples + +To prevent the currently installed Firefox from being upgraded: + +```console +$ nix-env --set-flag keep true firefox +``` + +After this, `nix-env -u` will ignore Firefox. + +To disable the currently installed Firefox, then install a new Firefox +while the old remains part of the profile: + +```console +$ nix-env -q +firefox-2.0.0.9 (the current one) + +$ nix-env --preserve-installed -i firefox-2.0.0.11 +installing `firefox-2.0.0.11' +building path(s) `/nix/store/myy0y59q3ig70dgq37jqwg1j0rsapzsl-user-environment' +collision between `/nix/store/...-firefox-2.0.0.11/bin/firefox' + and `/nix/store/...-firefox-2.0.0.9/bin/firefox'. +(i.e., can’t have two active at the same time) + +$ nix-env --set-flag active false firefox +setting flag on `firefox-2.0.0.9' + +$ nix-env --preserve-installed -i firefox-2.0.0.11 +installing `firefox-2.0.0.11' + +$ nix-env -q +firefox-2.0.0.11 (the enabled one) +firefox-2.0.0.9 (the disabled one) +``` + +To make files from `binutils` take precedence over files from `gcc`: + +```console +$ nix-env --set-flag priority 5 binutils +$ nix-env --set-flag priority 10 gcc +``` + +# Operation `--query` + +## Synopsis + +`nix-env` {`--query` | `-q`} *names…* + [`--installed` | `--available` | `-a`] + [{`--status` | `-s`}] + [{`--attr-path` | `-P`}] + [`--no-name`] + [{`--compare-versions` | `-c`}] + [`--system`] + [`--drv-path`] + [`--out-path`] + [`--description`] + [`--meta`] + [`--xml`] + [`--json`] + [{`--prebuilt-only` | `-b`}] + [{`--attr` | `-A`} *attribute-path*] + +## Description + +The query operation displays information about either the store paths +that are installed in the current generation of the active profile +(`--installed`), or the derivations that are available for installation +in the active Nix expression (`--available`). It only prints information +about derivations whose symbolic name matches one of *names*. + +The derivations are sorted by their `name` attributes. + +## Source selection + +The following flags specify the set of things on which the query +operates. + + - `--installed` + The query operates on the store paths that are installed in the + current generation of the active profile. This is the default. + + - `--available`; `-a` + The query operates on the derivations that are available in the + active Nix expression. + +## Queries + +The following flags specify what information to display about the +selected derivations. Multiple flags may be specified, in which case the +information is shown in the order given here. Note that the name of the +derivation is shown unless `--no-name` is specified. + + - `--xml` + Print the result in an XML representation suitable for automatic + processing by other tools. The root element is called `items`, which + contains a `item` element for each available or installed + derivation. The fields discussed below are all stored in attributes + of the `item` elements. + + - `--json` + Print the result in a JSON representation suitable for automatic + processing by other tools. + + - `--prebuilt-only` / `-b` + Show only derivations for which a substitute is registered, i.e., + there is a pre-built binary available that can be downloaded in lieu + of building the derivation. Thus, this shows all packages that + probably can be installed quickly. + + - `--status`; `-s` + Print the *status* of the derivation. The status consists of three + characters. The first is `I` or `-`, indicating whether the + derivation is currently installed in the current generation of the + active profile. This is by definition the case for `--installed`, + but not for `--available`. The second is `P` or `-`, indicating + whether the derivation is present on the system. This indicates + whether installation of an available derivation will require the + derivation to be built. The third is `S` or `-`, indicating whether + a substitute is available for the derivation. + + - `--attr-path`; `-P` + Print the *attribute path* of the derivation, which can be used to + unambiguously select it using the `--attr` option available in + commands that install derivations like `nix-env --install`. This + option only works together with `--available` + + - `--no-name` + Suppress printing of the `name` attribute of each derivation. + + - `--compare-versions` / `-c` + Compare installed versions to available versions, or vice versa (if + `--available` is given). This is useful for quickly seeing whether + upgrades for installed packages are available in a Nix expression. A + column is added with the following meaning: + + - `<` *version* + A newer version of the package is available or installed. + + - `=` *version* + At most the same version of the package is available or + installed. + + - `>` *version* + Only older versions of the package are available or installed. + + - `- ?` + No version of the package is available or installed. + + - `--system` + Print the `system` attribute of the derivation. + + - `--drv-path` + Print the path of the store derivation. + + - `--out-path` + Print the output path of the derivation. + + - `--description` + Print a short (one-line) description of the derivation, if + available. The description is taken from the `meta.description` + attribute of the derivation. + + - `--meta` + Print all of the meta-attributes of the derivation. This option is + only available with `--xml` or `--json`. + +## Examples + +To show installed packages: + +```console +$ nix-env -q +bison-1.875c +docbook-xml-4.2 +firefox-1.0.4 +MPlayer-1.0pre7 +ORBit2-2.8.3 +… +``` + +To show available packages: + +```console +$ nix-env -qa +firefox-1.0.7 +GConf-2.4.0.1 +MPlayer-1.0pre7 +ORBit2-2.8.3 +… +``` + +To show the status of available packages: + +```console +$ nix-env -qas +-P- firefox-1.0.7 (not installed but present) +--S GConf-2.4.0.1 (not present, but there is a substitute for fast installation) +--S MPlayer-1.0pre3 (i.e., this is not the installed MPlayer, even though the version is the same!) +IP- ORBit2-2.8.3 (installed and by definition present) +… +``` + +To show available packages in the Nix expression `foo.nix`: + +```console +$ nix-env -f ./foo.nix -qa +foo-1.2.3 +``` + +To compare installed versions to what’s available: + +```console +$ nix-env -qc +... +acrobat-reader-7.0 - ? (package is not available at all) +autoconf-2.59 = 2.59 (same version) +firefox-1.0.4 < 1.0.7 (a more recent version is available) +... +``` + +To show all packages with “`zip`” in the name: + +```console +$ nix-env -qa '.*zip.*' +bzip2-1.0.6 +gzip-1.6 +zip-3.0 +… +``` + +To show all packages with “`firefox`” or “`chromium`” in the name: + +```console +$ nix-env -qa '.*(firefox|chromium).*' +chromium-37.0.2062.94 +chromium-beta-38.0.2125.24 +firefox-32.0.3 +firefox-with-plugins-13.0.1 +… +``` + +To show all packages in the latest revision of the Nixpkgs repository: + +```console +$ nix-env -f https://github.com/NixOS/nixpkgs/archive/master.tar.gz -qa +``` + +# Operation `--switch-profile` + +## Synopsis + +`nix-env` {`--switch-profile` | `-S`} *path* + +## Description + +This operation makes *path* the current profile for the user. That is, +the symlink `~/.nix-profile` is made to point to *path*. + +## Examples + +```console +$ nix-env -S ~/my-profile +``` + +# Operation `--list-generations` + +## Synopsis + +`nix-env` `--list-generations` + +## Description + +This operation print a list of all the currently existing generations +for the active profile. These may be switched to using the +`--switch-generation` operation. It also prints the creation date of the +generation, and indicates the current generation. + +## Examples + +```console +$ nix-env --list-generations + 95 2004-02-06 11:48:24 + 96 2004-02-06 11:49:01 + 97 2004-02-06 16:22:45 + 98 2004-02-06 16:24:33 (current) +``` + +# Operation `--delete-generations` + +## Synopsis + +`nix-env` `--delete-generations` *generations* + +## Description + +This operation deletes the specified generations of the current profile. +The generations can be a list of generation numbers, the special value +`old` to delete all non-current generations, a value such as `30d` to +delete all generations older than the specified number of days (except +for the generation that was active at that point in time), or a value +such as `+5` to keep the last `5` generations ignoring any newer than +current, e.g., if `30` is the current generation `+5` will delete +generation `25` and all older generations. Periodically deleting old +generations is important to make garbage collection effective. + +## Examples + +```console +$ nix-env --delete-generations 3 4 8 +``` + +```console +$ nix-env --delete-generations +5 +``` + +```console +$ nix-env --delete-generations 30d +``` + +```console +$ nix-env -p other_profile --delete-generations old +``` + +# Operation `--switch-generation` + +## Synopsis + +`nix-env` {`--switch-generation` | `-G`} *generation* + +## Description + +This operation makes generation number *generation* the current +generation of the active profile. That is, if the `profile` is the path +to the active profile, then the symlink `profile` is made to point to +`profile-generation-link`, which is in turn a symlink to the actual user +environment in the Nix store. + +Switching will fail if the specified generation does not exist. + +## Examples + +```console +$ nix-env -G 42 +switching from generation 50 to 42 +``` + +# Operation `--rollback` + +## Synopsis + +`nix-env` `--rollback` + +## Description + +This operation switches to the “previous” generation of the active +profile, that is, the highest numbered generation lower than the current +generation, if it exists. It is just a convenience wrapper around +`--list-generations` and `--switch-generation`. + +## Examples + +```console +$ nix-env --rollback +switching from generation 92 to 91 +``` + +```console +$ nix-env --rollback +error: no generation older than the current (91) exists +``` + +# Environment variables + + - `NIX_PROFILE` + Location of the Nix profile. Defaults to the target of the symlink + `~/.nix-profile`, if it exists, or `/nix/var/nix/profiles/default` + otherwise. diff --git a/doc/manual/src/command-ref/nix-hash.md b/doc/manual/src/command-ref/nix-hash.md new file mode 100644 index 000000000..d3f91f8e9 --- /dev/null +++ b/doc/manual/src/command-ref/nix-hash.md @@ -0,0 +1,104 @@ +Title: nix-hash + +# Name + +`nix-hash` - compute the cryptographic hash of a path + +# Synopsis + +`nix-hash` [`--flat`] [`--base32`] [`--truncate`] [`--type` *hashAlgo*] *path…* + +`nix-hash` `--to-base16` *hash…* + +`nix-hash` `--to-base32` *hash…* + +# Description + +The command `nix-hash` computes the cryptographic hash of the contents +of each *path* and prints it on standard output. By default, it computes +an MD5 hash, but other hash algorithms are available as well. The hash +is printed in hexadecimal. To generate the same hash as +`nix-prefetch-url` you have to specify multiple arguments, see below for +an example. + +The hash is computed over a *serialisation* of each path: a dump of +the file system tree rooted at the path. This allows directories and +symlinks to be hashed as well as regular files. The dump is in the +*NAR format* produced by [`nix-store +--dump`](nix-store.md#operation---dump). Thus, `nix-hash path` +yields the same cryptographic hash as `nix-store --dump path | +md5sum`. + +# Options + + - `--flat` + Print the cryptographic hash of the contents of each regular file + *path*. That is, do not compute the hash over the dump of *path*. + The result is identical to that produced by the GNU commands + `md5sum` and `sha1sum`. + + - `--base32` + Print the hash in a base-32 representation rather than hexadecimal. + This base-32 representation is more compact and can be used in Nix + expressions (such as in calls to `fetchurl`). + + - `--truncate` + Truncate hashes longer than 160 bits (such as SHA-256) to 160 bits. + + - `--type` *hashAlgo* + Use the specified cryptographic hash algorithm, which can be one of + `md5`, `sha1`, and `sha256`. + + - `--to-base16` + Don’t hash anything, but convert the base-32 hash representation + *hash* to hexadecimal. + + - `--to-base32` + Don’t hash anything, but convert the hexadecimal hash representation + *hash* to base-32. + +# Examples + +Computing the same hash as `nix-prefetch-url`: + +```console +$ nix-prefetch-url file://<(echo test) +1lkgqb6fclns49861dwk9rzb6xnfkxbpws74mxnx01z9qyv1pjpj +$ nix-hash --type sha256 --flat --base32 <(echo test) +1lkgqb6fclns49861dwk9rzb6xnfkxbpws74mxnx01z9qyv1pjpj +``` + +Computing hashes: + +```console +$ mkdir test +$ echo "hello" > test/world + +$ nix-hash test/ (MD5 hash; default) +8179d3caeff1869b5ba1744e5a245c04 + +$ nix-store --dump test/ | md5sum (for comparison) +8179d3caeff1869b5ba1744e5a245c04 - + +$ nix-hash --type sha1 test/ +e4fd8ba5f7bbeaea5ace89fe10255536cd60dab6 + +$ nix-hash --type sha1 --base32 test/ +nvd61k9nalji1zl9rrdfmsmvyyjqpzg4 + +$ nix-hash --type sha256 --flat test/ +error: reading file `test/': Is a directory + +$ nix-hash --type sha256 --flat test/world +5891b5b522d5df086d0ff0b110fbd9d21bb4fc7163af34d08286a2e846f6be03 +``` + +Converting between hexadecimal and base-32: + +```console +$ nix-hash --type sha1 --to-base32 e4fd8ba5f7bbeaea5ace89fe10255536cd60dab6 +nvd61k9nalji1zl9rrdfmsmvyyjqpzg4 + +$ nix-hash --type sha1 --to-base16 nvd61k9nalji1zl9rrdfmsmvyyjqpzg4 +e4fd8ba5f7bbeaea5ace89fe10255536cd60dab6 +``` diff --git a/doc/manual/src/command-ref/nix-instantiate.md b/doc/manual/src/command-ref/nix-instantiate.md new file mode 100644 index 000000000..d09f5ed6a --- /dev/null +++ b/doc/manual/src/command-ref/nix-instantiate.md @@ -0,0 +1,160 @@ +Title: nix-instantiate + +# Name + +`nix-instantiate` - instantiate store derivations from Nix expressions + +# Synopsis + +`nix-instantiate` + [`--parse` | `--eval` [`--strict`] [`--json`] [`--xml`] ] + [`--read-write-mode`] + [`--arg` *name* *value*] + [{`--attr`| `-A`} *attrPath*] + [`--add-root` *path*] + [`--expr` | `-E`] + *files…* + +`nix-instantiate` `--find-file` *files…* + +# Description + +The command `nix-instantiate` generates [store +derivations](../glossary.md) from (high-level) Nix expressions. It +evaluates the Nix expressions in each of *files* (which defaults to +*./default.nix*). Each top-level expression should evaluate to a +derivation, a list of derivations, or a set of derivations. The paths +of the resulting store derivations are printed on standard output. + +If *files* is the character `-`, then a Nix expression will be read from +standard input. + +# Options + + - `--add-root` *path* + See the [corresponding option](nix-store.md) in `nix-store`. + + - `--parse` + Just parse the input files, and print their abstract syntax trees on + standard output in ATerm format. + + - `--eval` + Just parse and evaluate the input files, and print the resulting + values on standard output. No instantiation of store derivations + takes place. + + - `--find-file` + Look up the given files in Nix’s search path (as specified by the + `NIX_PATH` environment variable). If found, print the corresponding + absolute paths on standard output. For instance, if `NIX_PATH` is + `nixpkgs=/home/alice/nixpkgs`, then `nix-instantiate --find-file + nixpkgs/default.nix` will print `/home/alice/nixpkgs/default.nix`. + + - `--strict` + When used with `--eval`, recursively evaluate list elements and + attributes. Normally, such sub-expressions are left unevaluated + (since the Nix expression language is lazy). + + > **Warning** + > + > This option can cause non-termination, because lazy data + > structures can be infinitely large. + + - `--json` + When used with `--eval`, print the resulting value as an JSON + representation of the abstract syntax tree rather than as an ATerm. + + - `--xml` + When used with `--eval`, print the resulting value as an XML + representation of the abstract syntax tree rather than as an ATerm. + The schema is the same as that used by the [`toXML` + built-in](../expressions/builtins.md). + + - `--read-write-mode` + When used with `--eval`, perform evaluation in read/write mode so + nix language features that require it will still work (at the cost + of needing to do instantiation of every evaluated derivation). If + this option is not enabled, there may be uninstantiated store paths + in the final output. + +<!-- end list --> + +# Examples + +Instantiating store derivations from a Nix expression, and building them +using `nix-store`: + +```console +$ nix-instantiate test.nix (instantiate) +/nix/store/cigxbmvy6dzix98dxxh9b6shg7ar5bvs-perl-BerkeleyDB-0.26.drv + +$ nix-store -r $(nix-instantiate test.nix) (build) +... +/nix/store/qhqk4n8ci095g3sdp93x7rgwyh9rdvgk-perl-BerkeleyDB-0.26 (output path) + +$ ls -l /nix/store/qhqk4n8ci095g3sdp93x7rgwyh9rdvgk-perl-BerkeleyDB-0.26 +dr-xr-xr-x 2 eelco users 4096 1970-01-01 01:00 lib +... +``` + +You can also give a Nix expression on the command line: + +```console +$ nix-instantiate -E 'with import <nixpkgs> { }; hello' +/nix/store/j8s4zyv75a724q38cb0r87rlczaiag4y-hello-2.8.drv +``` + +This is equivalent to: + +```console +$ nix-instantiate '<nixpkgs>' -A hello +``` + +Parsing and evaluating Nix expressions: + +```console +$ nix-instantiate --parse -E '1 + 2' +1 + 2 +``` + +```console +$ nix-instantiate --eval -E '1 + 2' +3 +``` + +```console +$ nix-instantiate --eval --xml -E '1 + 2' +<?xml version='1.0' encoding='utf-8'?> +<expr> + <int value="3" /> +</expr> +``` + +The difference between non-strict and strict evaluation: + +```console +$ nix-instantiate --eval --xml -E 'rec { x = "foo"; y = x; }' +... + <attr name="x"> + <string value="foo" /> + </attr> + <attr name="y"> + <unevaluated /> + </attr> +... +``` + +Note that `y` is left unevaluated (the XML representation doesn’t +attempt to show non-normal forms). + +```console +$ nix-instantiate --eval --xml --strict -E 'rec { x = "foo"; y = x; }' +... + <attr name="x"> + <string value="foo" /> + </attr> + <attr name="y"> + <string value="foo" /> + </attr> +... +``` diff --git a/doc/manual/src/command-ref/nix-prefetch-url.md b/doc/manual/src/command-ref/nix-prefetch-url.md new file mode 100644 index 000000000..1cd1063cd --- /dev/null +++ b/doc/manual/src/command-ref/nix-prefetch-url.md @@ -0,0 +1,77 @@ +Title: nix-prefetch-url + +# Name + +`nix-prefetch-url` - copy a file from a URL into the store and print its hash + +# Synopsis + +`nix-prefetch-url` *url* [*hash*] + [`--type` *hashAlgo*] + [`--print-path`] + [`--unpack`] + [`--name` *name*] + +# Description + +The command `nix-prefetch-url` downloads the file referenced by the URL +*url*, prints its cryptographic hash, and copies it into the Nix store. +The file name in the store is `hash-baseName`, where *baseName* is +everything following the final slash in *url*. + +This command is just a convenience for Nix expression writers. Often a +Nix expression fetches some source distribution from the network using +the `fetchurl` expression contained in Nixpkgs. However, `fetchurl` +requires a cryptographic hash. If you don't know the hash, you would +have to download the file first, and then `fetchurl` would download it +again when you build your Nix expression. Since `fetchurl` uses the same +name for the downloaded file as `nix-prefetch-url`, the redundant +download can be avoided. + +If *hash* is specified, then a download is not performed if the Nix +store already contains a file with the same hash and base name. +Otherwise, the file is downloaded, and an error is signaled if the +actual hash of the file does not match the specified hash. + +This command prints the hash on standard output. Additionally, if the +option `--print-path` is used, the path of the downloaded file in the +Nix store is also printed. + +# Options + + - `--type` *hashAlgo* + Use the specified cryptographic hash algorithm, which can be one of + `md5`, `sha1`, and `sha256`. + + - `--print-path` + Print the store path of the downloaded file on standard output. + + - `--unpack` + Unpack the archive (which must be a tarball or zip file) and add the + result to the Nix store. The resulting hash can be used with + functions such as Nixpkgs’s `fetchzip` or `fetchFromGitHub`. + + - `--name` *name* + Override the name of the file in the Nix store. By default, this is + `hash-basename`, where *basename* is the last component of *url*. + Overriding the name is necessary when *basename* contains characters + that are not allowed in Nix store paths. + +# Examples + +```console +$ nix-prefetch-url ftp://ftp.gnu.org/pub/gnu/hello/hello-2.10.tar.gz +0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i +``` + +```console +$ nix-prefetch-url --print-path mirror://gnu/hello/hello-2.10.tar.gz +0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i +/nix/store/3x7dwzq014bblazs7kq20p9hyzz0qh8g-hello-2.10.tar.gz +``` + +```console +$ nix-prefetch-url --unpack --print-path https://github.com/NixOS/patchelf/archive/0.8.tar.gz +079agjlv0hrv7fxnx9ngipx14gyncbkllxrp9cccnh3a50fxcmy7 +/nix/store/19zrmhm3m40xxaw81c8cqm6aljgrnwj2-0.8.tar.gz +``` diff --git a/doc/manual/src/command-ref/nix-shell.md b/doc/manual/src/command-ref/nix-shell.md new file mode 100644 index 000000000..fc42a202a --- /dev/null +++ b/doc/manual/src/command-ref/nix-shell.md @@ -0,0 +1,276 @@ +Title: nix-shell + +# Name + +`nix-shell` - start an interactive shell based on a Nix expression + +# Synopsis + +`nix-shell` + [`--arg` *name* *value*] + [`--argstr` *name* *value*] + [{`--attr` | `-A`} *attrPath*] + [`--command` *cmd*] + [`--run` *cmd*] + [`--exclude` *regexp*] + [--pure] + [--keep *name*] + {{`--packages` | `-p`} {*packages* | *expressions*} … | [*path*]} + +# Description + +The command `nix-shell` will build the dependencies of the specified +derivation, but not the derivation itself. It will then start an +interactive shell in which all environment variables defined by the +derivation *path* have been set to their corresponding values, and the +script `$stdenv/setup` has been sourced. This is useful for reproducing +the environment of a derivation for development. + +If *path* is not given, `nix-shell` defaults to `shell.nix` if it +exists, and `default.nix` otherwise. + +If *path* starts with `http://` or `https://`, it is interpreted as the +URL of a tarball that will be downloaded and unpacked to a temporary +location. The tarball must include a single top-level directory +containing at least a file named `default.nix`. + +If the derivation defines the variable `shellHook`, it will be evaluated +after `$stdenv/setup` has been sourced. Since this hook is not executed +by regular Nix builds, it allows you to perform initialisation specific +to `nix-shell`. For example, the derivation attribute + +```nix +shellHook = + '' + echo "Hello shell" + ''; +``` + +will cause `nix-shell` to print `Hello shell`. + +# Options + +All options not listed here are passed to `nix-store +--realise`, except for `--arg` and `--attr` / `-A` which are passed to +`nix-instantiate`. + + - `--command` *cmd* + In the environment of the derivation, run the shell command *cmd*. + This command is executed in an interactive shell. (Use `--run` to + use a non-interactive shell instead.) However, a call to `exit` is + implicitly added to the command, so the shell will exit after + running the command. To prevent this, add `return` at the end; + e.g. `--command "echo Hello; return"` will print `Hello` and then + drop you into the interactive shell. This can be useful for doing + any additional initialisation. + + - `--run` *cmd* + Like `--command`, but executes the command in a non-interactive + shell. This means (among other things) that if you hit Ctrl-C while + the command is running, the shell exits. + + - `--exclude` *regexp* + Do not build any dependencies whose store path matches the regular + expression *regexp*. This option may be specified multiple times. + + - `--pure` + If this flag is specified, the environment is almost entirely + cleared before the interactive shell is started, so you get an + environment that more closely corresponds to the “real” Nix build. A + few variables, in particular `HOME`, `USER` and `DISPLAY`, are + retained. Note that `~/.bashrc` and (depending on your Bash + installation) `/etc/bashrc` are still sourced, so any variables set + there will affect the interactive shell. + + - `--packages` / `-p` *packages*… + Set up an environment in which the specified packages are present. + The command line arguments are interpreted as attribute names inside + the Nix Packages collection. Thus, `nix-shell -p libjpeg openjdk` + will start a shell in which the packages denoted by the attribute + names `libjpeg` and `openjdk` are present. + + - `-i` *interpreter* + The chained script interpreter to be invoked by `nix-shell`. Only + applicable in `#!`-scripts (described below). + + - `--keep` *name* + When a `--pure` shell is started, keep the listed environment + variables. + +The following common options are supported: + +# Environment variables + + - `NIX_BUILD_SHELL` + Shell used to start the interactive environment. Defaults to the + `bash` found in `PATH`. + +# Examples + +To build the dependencies of the package Pan, and start an interactive +shell in which to build it: + +```console +$ nix-shell '<nixpkgs>' -A pan +[nix-shell]$ unpackPhase +[nix-shell]$ cd pan-* +[nix-shell]$ configurePhase +[nix-shell]$ buildPhase +[nix-shell]$ ./pan/gui/pan +``` + +To clear the environment first, and do some additional automatic +initialisation of the interactive shell: + +```console +$ nix-shell '<nixpkgs>' -A pan --pure \ + --command 'export NIX_DEBUG=1; export NIX_CORES=8; return' +``` + +Nix expressions can also be given on the command line using the `-E` and +`-p` flags. For instance, the following starts a shell containing the +packages `sqlite` and `libX11`: + +```console +$ nix-shell -E 'with import <nixpkgs> { }; runCommand "dummy" { buildInputs = [ sqlite xorg.libX11 ]; } ""' +``` + +A shorter way to do the same is: + +```console +$ nix-shell -p sqlite xorg.libX11 +[nix-shell]$ echo $NIX_LDFLAGS +… -L/nix/store/j1zg5v…-sqlite-3.8.0.2/lib -L/nix/store/0gmcz9…-libX11-1.6.1/lib … +``` + +Note that `-p` accepts multiple full nix expressions that are valid in +the `buildInputs = [ ... ]` shown above, not only package names. So the +following is also legal: + +```console +$ nix-shell -p sqlite 'git.override { withManual = false; }' +``` + +The `-p` flag looks up Nixpkgs in the Nix search path. You can override +it by passing `-I` or setting `NIX_PATH`. For example, the following +gives you a shell containing the Pan package from a specific revision of +Nixpkgs: + +```console +$ nix-shell -p pan -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/8a3eea054838b55aca962c3fbde9c83c102b8bf2.tar.gz + +[nix-shell:~]$ pan --version +Pan 0.139 +``` + +# Use as a `#!`-interpreter + +You can use `nix-shell` as a script interpreter to allow scripts written +in arbitrary languages to obtain their own dependencies via Nix. This is +done by starting the script with the following lines: + +```bash +#! /usr/bin/env nix-shell +#! nix-shell -i real-interpreter -p packages +``` + +where *real-interpreter* is the “real” script interpreter that will be +invoked by `nix-shell` after it has obtained the dependencies and +initialised the environment, and *packages* are the attribute names of +the dependencies in Nixpkgs. + +The lines starting with `#! nix-shell` specify `nix-shell` options (see +above). Note that you cannot write `#! /usr/bin/env nix-shell -i ...` +because many operating systems only allow one argument in `#!` lines. + +For example, here is a Python script that depends on Python and the +`prettytable` package: + +```python +#! /usr/bin/env nix-shell +#! nix-shell -i python -p python pythonPackages.prettytable + +import prettytable + +# Print a simple table. +t = prettytable.PrettyTable(["N", "N^2"]) +for n in range(1, 10): t.add_row([n, n * n]) +print t +``` + +Similarly, the following is a Perl script that specifies that it +requires Perl and the `HTML::TokeParser::Simple` and `LWP` packages: + +```perl +#! /usr/bin/env nix-shell +#! nix-shell -i perl -p perl perlPackages.HTMLTokeParserSimple perlPackages.LWP + +use HTML::TokeParser::Simple; + +# Fetch nixos.org and print all hrefs. +my $p = HTML::TokeParser::Simple->new(url => 'http://nixos.org/'); + +while (my $token = $p->get_tag("a")) { + my $href = $token->get_attr("href"); + print "$href\n" if $href; +} +``` + +Sometimes you need to pass a simple Nix expression to customize a +package like Terraform: + +```bash +#! /usr/bin/env nix-shell +#! nix-shell -i bash -p "terraform.withPlugins (plugins: [ plugins.openstack ])" + +terraform apply +``` + +> **Note** +> +> You must use double quotes (`"`) when passing a simple Nix expression +> in a nix-shell shebang. + +Finally, using the merging of multiple nix-shell shebangs the following +Haskell script uses a specific branch of Nixpkgs/NixOS (the 18.03 stable +branch): + +```haskell +#! /usr/bin/env nix-shell +#! nix-shell -i runghc -p "haskellPackages.ghcWithPackages (ps: [ps.HTTP ps.tagsoup])" +#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixos-18.03.tar.gz + +import Network.HTTP +import Text.HTML.TagSoup + +-- Fetch nixos.org and print all hrefs. +main = do + resp <- Network.HTTP.simpleHTTP (getRequest "http://nixos.org/") + body <- getResponseBody resp + let tags = filter (isTagOpenName "a") $ parseTags body + let tags' = map (fromAttrib "href") tags + mapM_ putStrLn $ filter (/= "") tags' +``` + +If you want to be even more precise, you can specify a specific revision +of Nixpkgs: + + #! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/0672315759b3e15e2121365f067c1c8c56bb4722.tar.gz + +The examples above all used `-p` to get dependencies from Nixpkgs. You +can also use a Nix expression to build your own dependencies. For +example, the Python example could have been written as: + +```python +#! /usr/bin/env nix-shell +#! nix-shell deps.nix -i python +``` + +where the file `deps.nix` in the same directory as the `#!`-script +contains: + +```nix +with import <nixpkgs> {}; + +runCommand "dummy" { buildInputs = [ python pythonPackages.prettytable ]; } "" +``` diff --git a/doc/manual/src/command-ref/nix-store.md b/doc/manual/src/command-ref/nix-store.md new file mode 100644 index 000000000..4680339e4 --- /dev/null +++ b/doc/manual/src/command-ref/nix-store.md @@ -0,0 +1,835 @@ +Title: nix-store + +# Name + +`nix-store` - manipulate or query the Nix store + +# Synopsis + +`nix-store` *operation* [*options…*] [*arguments…*] + [`--option` *name* *value*] + [`--add-root` *path*] + +# Description + +The command `nix-store` performs primitive operations on the Nix store. +You generally do not need to run this command manually. + +`nix-store` takes exactly one *operation* flag which indicates the +subcommand to be performed. These are documented below. + +# Common options + +This section lists the options that are common to all operations. These +options are allowed for every subcommand, though they may not always +have an effect. + + - `--add-root` *path* + Causes the result of a realisation (`--realise` and + `--force-realise`) to be registered as a root of the garbage + collector. *path* will be created as a symlink to the resulting + store path. In addition, a uniquely named symlink to *path* will + be created in `/nix/var/nix/gcroots/auto/`. For instance, + + ```console + $ nix-store --add-root /home/eelco/bla/result -r ... + + $ ls -l /nix/var/nix/gcroots/auto + lrwxrwxrwx 1 ... 2005-03-13 21:10 dn54lcypm8f8... -> /home/eelco/bla/result + + $ ls -l /home/eelco/bla/result + lrwxrwxrwx 1 ... 2005-03-13 21:10 /home/eelco/bla/result -> /nix/store/1r11343n6qd4...-f-spot-0.0.10 + ``` + + Thus, when `/home/eelco/bla/result` is removed, the GC root in the + `auto` directory becomes a dangling symlink and will be ignored by + the collector. + + > **Warning** + > + > Note that it is not possible to move or rename GC roots, since + > the symlink in the `auto` directory will still point to the old + > location. + + If there are multiple results, then multiple symlinks will be + created by sequentially numbering symlinks beyond the first one + (e.g., `foo`, `foo-2`, `foo-3`, and so on). + +# Operation `--realise` + +## Synopsis + +`nix-store` {`--realise` | `-r`} *paths…* [`--dry-run`] + +## Description + +The operation `--realise` essentially “builds” the specified store +paths. Realisation is a somewhat overloaded term: + + - If the store path is a *derivation*, realisation ensures that the + output paths of the derivation are [valid](../glossary.md) (i.e., + the output path and its closure exist in the file system). This + can be done in several ways. First, it is possible that the + outputs are already valid, in which case we are done + immediately. Otherwise, there may be [substitutes](../glossary.md) + that produce the outputs (e.g., by downloading them). Finally, the + outputs can be produced by performing the build action described + by the derivation. + + - If the store path is not a derivation, realisation ensures that the + specified path is valid (i.e., it and its closure exist in the file + system). If the path is already valid, we are done immediately. + Otherwise, the path and any missing paths in its closure may be + produced through substitutes. If there are no (successful) + subsitutes, realisation fails. + +The output path of each derivation is printed on standard output. (For +non-derivations argument, the argument itself is printed.) + +The following flags are available: + + - `--dry-run` + Print on standard error a description of what packages would be + built or downloaded, without actually performing the operation. + + - `--ignore-unknown` + If a non-derivation path does not have a substitute, then silently + ignore it. + + - `--check` + This option allows you to check whether a derivation is + deterministic. It rebuilds the specified derivation and checks + whether the result is bitwise-identical with the existing outputs, + printing an error if that’s not the case. The outputs of the + specified derivation must already exist. When used with `-K`, if an + output path is not identical to the corresponding output from the + previous build, the new output path is left in + `/nix/store/name.check.` + + See also the `build-repeat` configuration option, which repeats a + derivation a number of times and prevents its outputs from being + registered as “valid” in the Nix store unless they are identical. + +Special exit codes: + + - `100` + Generic build failure, the builder process returned with a non-zero + exit code. + + - `101` + Build timeout, the build was aborted because it did not complete + within the specified `timeout`. + + - `102` + Hash mismatch, the build output was rejected because it does not + match the [`outputHash` attribute of the + derivation](../expressions/advanced-attributes.md). + + - `104` + Not deterministic, the build succeeded in check mode but the + resulting output is not binary reproducable. + +With the `--keep-going` flag it's possible for multiple failures to +occur, in this case the 1xx status codes are or combined using binary +or. + + 1100100 + ^^^^ + |||`- timeout + ||`-- output hash mismatch + |`--- build failure + `---- not deterministic + +## Examples + +This operation is typically used to build store derivations produced by +[`nix-instantiate`](nix-instantiate.md): + +```console +$ nix-store -r $(nix-instantiate ./test.nix) +/nix/store/31axcgrlbfsxzmfff1gyj1bf62hvkby2-aterm-2.3.1 +``` + +This is essentially what [`nix-build`](nix-build.md) does. + +To test whether a previously-built derivation is deterministic: + +```console +$ nix-build '<nixpkgs>' -A hello --check -K +``` + +# Operation `--serve` + +## Synopsis + +`nix-store` `--serve` [`--write`] + +## Description + +The operation `--serve` provides access to the Nix store over stdin and +stdout, and is intended to be used as a means of providing Nix store +access to a restricted ssh user. + +The following flags are available: + + - `--write` + Allow the connected client to request the realization of + derivations. In effect, this can be used to make the host act as a + remote builder. + +## Examples + +To turn a host into a build server, the `authorized_keys` file can be +used to provide build access to a given SSH public key: + +```console +$ cat <<EOF >>/root/.ssh/authorized_keys +command="nice -n20 nix-store --serve --write" ssh-rsa AAAAB3NzaC1yc2EAAAA... +EOF +``` + +# Operation `--gc` + +## Synopsis + +`nix-store` `--gc` [`--print-roots` | `--print-live` | `--print-dead`] [`--max-freed` *bytes*] + +## Description + +Without additional flags, the operation `--gc` performs a garbage +collection on the Nix store. That is, all paths in the Nix store not +reachable via file system references from a set of “roots”, are deleted. + +The following suboperations may be specified: + + - `--print-roots` + This operation prints on standard output the set of roots used by + the garbage collector. + + - `--print-live` + This operation prints on standard output the set of “live” store + paths, which are all the store paths reachable from the roots. Live + paths should never be deleted, since that would break consistency — + it would become possible that applications are installed that + reference things that are no longer present in the store. + + - `--print-dead` + This operation prints out on standard output the set of “dead” store + paths, which is just the opposite of the set of live paths: any path + in the store that is not live (with respect to the roots) is dead. + +By default, all unreachable paths are deleted. The following options +control what gets deleted and in what order: + + - `--max-freed` *bytes* + Keep deleting paths until at least *bytes* bytes have been deleted, + then stop. The argument *bytes* can be followed by the + multiplicative suffix `K`, `M`, `G` or `T`, denoting KiB, MiB, GiB + or TiB units. + +The behaviour of the collector is also influenced by the +`keep-outputs` and `keep-derivations` variables in the Nix +configuration file. + +By default, the collector prints the total number of freed bytes when it +finishes (or when it is interrupted). With `--print-dead`, it prints the +number of bytes that would be freed. + +## Examples + +To delete all unreachable paths, just do: + +```console +$ nix-store --gc +deleting `/nix/store/kq82idx6g0nyzsp2s14gfsc38npai7lf-cairo-1.0.4.tar.gz.drv' +... +8825586 bytes freed (8.42 MiB) +``` + +To delete at least 100 MiBs of unreachable paths: + +```console +$ nix-store --gc --max-freed $((100 * 1024 * 1024)) +``` + +# Operation `--delete` + +## Synopsis + +`nix-store` `--delete` [`--ignore-liveness`] *paths…* + +## Description + +The operation `--delete` deletes the store paths *paths* from the Nix +store, but only if it is safe to do so; that is, when the path is not +reachable from a root of the garbage collector. This means that you can +only delete paths that would also be deleted by `nix-store --gc`. Thus, +`--delete` is a more targeted version of `--gc`. + +With the option `--ignore-liveness`, reachability from the roots is +ignored. However, the path still won’t be deleted if there are other +paths in the store that refer to it (i.e., depend on it). + +## Example + +```console +$ nix-store --delete /nix/store/zq0h41l75vlb4z45kzgjjmsjxvcv1qk7-mesa-6.4 +0 bytes freed (0.00 MiB) +error: cannot delete path `/nix/store/zq0h41l75vlb4z45kzgjjmsjxvcv1qk7-mesa-6.4' since it is still alive +``` + +# Operation `--query` + +## Synopsis + +`nix-store` {`--query` | `-q`} + {`--outputs` | `--requisites` | `-R` | `--references` | + `--referrers` | `--referrers-closure` | `--deriver` | `-d` | + `--graph` | `--tree` | `--binding` *name* | `-b` *name* | `--hash` | + `--size` | `--roots`} + [`--use-output`] [`-u`] [`--force-realise`] [`-f`] + *paths…* + +## Description + +The operation `--query` displays various bits of information about the +store paths . The queries are described below. At most one query can be +specified. The default query is `--outputs`. + +The paths *paths* may also be symlinks from outside of the Nix store, to +the Nix store. In that case, the query is applied to the target of the +symlink. + +## Common query options + + - `--use-output`; `-u` + For each argument to the query that is a store derivation, apply the + query to the output path of the derivation instead. + + - `--force-realise`; `-f` + Realise each argument to the query first (see [`nix-store + --realise`](#operation---realise)). + +## Queries + + - `--outputs` + Prints out the [output paths](../glossary.md) of the store + derivations *paths*. These are the paths that will be produced when + the derivation is built. + + - `--requisites`; `-R` + Prints out the [closure](../glossary.md) of the store path *paths*. + + This query has one option: + + - `--include-outputs` + Also include the output path of store derivations, and their + closures. + + This query can be used to implement various kinds of deployment. A + *source deployment* is obtained by distributing the closure of a + store derivation. A *binary deployment* is obtained by distributing + the closure of an output path. A *cache deployment* (combined + source/binary deployment, including binaries of build-time-only + dependencies) is obtained by distributing the closure of a store + derivation and specifying the option `--include-outputs`. + + - `--references` + Prints the set of [references](../glossary.md) of the store paths + *paths*, that is, their immediate dependencies. (For *all* + dependencies, use `--requisites`.) + + - `--referrers` + Prints the set of *referrers* of the store paths *paths*, that is, + the store paths currently existing in the Nix store that refer to + one of *paths*. Note that contrary to the references, the set of + referrers is not constant; it can change as store paths are added or + removed. + + - `--referrers-closure` + Prints the closure of the set of store paths *paths* under the + referrers relation; that is, all store paths that directly or + indirectly refer to one of *paths*. These are all the path currently + in the Nix store that are dependent on *paths*. + + - `--deriver`; `-d` + Prints the [deriver](../glossary.md) of the store paths *paths*. If + the path has no deriver (e.g., if it is a source file), or if the + deriver is not known (e.g., in the case of a binary-only + deployment), the string `unknown-deriver` is printed. + + - `--graph` + Prints the references graph of the store paths *paths* in the format + of the `dot` tool of AT\&T's [Graphviz + package](http://www.graphviz.org/). This can be used to visualise + dependency graphs. To obtain a build-time dependency graph, apply + this to a store derivation. To obtain a runtime dependency graph, + apply it to an output path. + + - `--tree` + Prints the references graph of the store paths *paths* as a nested + ASCII tree. References are ordered by descending closure size; this + tends to flatten the tree, making it more readable. The query only + recurses into a store path when it is first encountered; this + prevents a blowup of the tree representation of the graph. + + - `--graphml` + Prints the references graph of the store paths *paths* in the + [GraphML](http://graphml.graphdrawing.org/) file format. This can be + used to visualise dependency graphs. To obtain a build-time + dependency graph, apply this to a store derivation. To obtain a + runtime dependency graph, apply it to an output path. + + - `--binding` *name*; `-b` *name* + Prints the value of the attribute *name* (i.e., environment + variable) of the store derivations *paths*. It is an error for a + derivation to not have the specified attribute. + + - `--hash` + Prints the SHA-256 hash of the contents of the store paths *paths* + (that is, the hash of the output of `nix-store --dump` on the given + paths). Since the hash is stored in the Nix database, this is a fast + operation. + + - `--size` + Prints the size in bytes of the contents of the store paths *paths* + — to be precise, the size of the output of `nix-store --dump` on + the given paths. Note that the actual disk space required by the + store paths may be higher, especially on filesystems with large + cluster sizes. + + - `--roots` + Prints the garbage collector roots that point, directly or + indirectly, at the store paths *paths*. + +## Examples + +Print the closure (runtime dependencies) of the `svn` program in the +current user environment: + +```console +$ nix-store -qR $(which svn) +/nix/store/5mbglq5ldqld8sj57273aljwkfvj22mc-subversion-1.1.4 +/nix/store/9lz9yc6zgmc0vlqmn2ipcpkjlmbi51vv-glibc-2.3.4 +... +``` + +Print the build-time dependencies of `svn`: + +```console +$ nix-store -qR $(nix-store -qd $(which svn)) +/nix/store/02iizgn86m42q905rddvg4ja975bk2i4-grep-2.5.1.tar.bz2.drv +/nix/store/07a2bzxmzwz5hp58nf03pahrv2ygwgs3-gcc-wrapper.sh +/nix/store/0ma7c9wsbaxahwwl04gbw3fcd806ski4-glibc-2.3.4.drv +... lots of other paths ... +``` + +The difference with the previous example is that we ask the closure of +the derivation (`-qd`), not the closure of the output path that contains +`svn`. + +Show the build-time dependencies as a tree: + +```console +$ nix-store -q --tree $(nix-store -qd $(which svn)) +/nix/store/7i5082kfb6yjbqdbiwdhhza0am2xvh6c-subversion-1.1.4.drv ++---/nix/store/d8afh10z72n8l1cr5w42366abiblgn54-builder.sh ++---/nix/store/fmzxmpjx2lh849ph0l36snfj9zdibw67-bash-3.0.drv +| +---/nix/store/570hmhmx3v57605cqg9yfvvyh0nnb8k8-bash +| +---/nix/store/p3srsbd8dx44v2pg6nbnszab5mcwx03v-builder.sh +... +``` + +Show all paths that depend on the same OpenSSL library as `svn`: + +```console +$ nix-store -q --referrers $(nix-store -q --binding openssl $(nix-store -qd $(which svn))) +/nix/store/23ny9l9wixx21632y2wi4p585qhva1q8-sylpheed-1.0.0 +/nix/store/5mbglq5ldqld8sj57273aljwkfvj22mc-subversion-1.1.4 +/nix/store/dpmvp969yhdqs7lm2r1a3gng7pyq6vy4-subversion-1.1.3 +/nix/store/l51240xqsgg8a7yrbqdx1rfzyv6l26fx-lynx-2.8.5 +``` + +Show all paths that directly or indirectly depend on the Glibc (C +library) used by `svn`: + +```console +$ nix-store -q --referrers-closure $(ldd $(which svn) | grep /libc.so | awk '{print $3}') +/nix/store/034a6h4vpz9kds5r6kzb9lhh81mscw43-libgnomeprintui-2.8.2 +/nix/store/15l3yi0d45prm7a82pcrknxdh6nzmxza-gawk-3.1.4 +... +``` + +Note that `ldd` is a command that prints out the dynamic libraries used +by an ELF executable. + +Make a picture of the runtime dependency graph of the current user +environment: + +```console +$ nix-store -q --graph ~/.nix-profile | dot -Tps > graph.ps +$ gv graph.ps +``` + +Show every garbage collector root that points to a store path that +depends on `svn`: + +```console +$ nix-store -q --roots $(which svn) +/nix/var/nix/profiles/default-81-link +/nix/var/nix/profiles/default-82-link +/nix/var/nix/profiles/per-user/eelco/profile-97-link +``` + +# Operation `--add` + +## Synopsis + +`nix-store` `--add` *paths…* + +## Description + +The operation `--add` adds the specified paths to the Nix store. It +prints the resulting paths in the Nix store on standard output. + +## Example + +```console +$ nix-store --add ./foo.c +/nix/store/m7lrha58ph6rcnv109yzx1nk1cj7k7zf-foo.c +``` + +# Operation `--add-fixed` + +## Synopsis + +`nix-store` `--add-fixed` [`--recursive`] *algorithm* *paths…* + +## Description + +The operation `--add-fixed` adds the specified paths to the Nix store. +Unlike `--add` paths are registered using the specified hashing +algorithm, resulting in the same output path as a fixed-output +derivation. This can be used for sources that are not available from a +public url or broke since the download expression was written. + +This operation has the following options: + + - `--recursive` + Use recursive instead of flat hashing mode, used when adding + directories to the store. + +## Example + +```console +$ nix-store --add-fixed sha256 ./hello-2.10.tar.gz +/nix/store/3x7dwzq014bblazs7kq20p9hyzz0qh8g-hello-2.10.tar.gz +``` + +# Operation `--verify` + +## Synopsis + +`nix-store` `--verify` [`--check-contents`] [`--repair`] + +## Description + +The operation `--verify` verifies the internal consistency of the Nix +database, and the consistency between the Nix database and the Nix +store. Any inconsistencies encountered are automatically repaired. +Inconsistencies are generally the result of the Nix store or database +being modified by non-Nix tools, or of bugs in Nix itself. + +This operation has the following options: + + - `--check-contents` + Checks that the contents of every valid store path has not been + altered by computing a SHA-256 hash of the contents and comparing it + with the hash stored in the Nix database at build time. Paths that + have been modified are printed out. For large stores, + `--check-contents` is obviously quite slow. + + - `--repair` + If any valid path is missing from the store, or (if + `--check-contents` is given) the contents of a valid path has been + modified, then try to repair the path by redownloading it. See + `nix-store --repair-path` for details. + +# Operation `--verify-path` + +## Synopsis + +`nix-store` `--verify-path` *paths…* + +## Description + +The operation `--verify-path` compares the contents of the given store +paths to their cryptographic hashes stored in Nix’s database. For every +changed path, it prints a warning message. The exit status is 0 if no +path has changed, and 1 otherwise. + +## Example + +To verify the integrity of the `svn` command and all its dependencies: + +```console +$ nix-store --verify-path $(nix-store -qR $(which svn)) +``` + +# Operation `--repair-path` + +## Synopsis + +`nix-store` `--repair-path` *paths…* + +## Description + +The operation `--repair-path` attempts to “repair” the specified paths +by redownloading them using the available substituters. If no +substitutes are available, then repair is not possible. + +> **Warning** +> +> During repair, there is a very small time window during which the old +> path (if it exists) is moved out of the way and replaced with the new +> path. If repair is interrupted in between, then the system may be left +> in a broken state (e.g., if the path contains a critical system +> component like the GNU C Library). + +## Example + +```console +$ nix-store --verify-path /nix/store/dj7a81wsm1ijwwpkks3725661h3263p5-glibc-2.13 +path `/nix/store/dj7a81wsm1ijwwpkks3725661h3263p5-glibc-2.13' was modified! + expected hash `2db57715ae90b7e31ff1f2ecb8c12ec1cc43da920efcbe3b22763f36a1861588', + got `481c5aa5483ebc97c20457bb8bca24deea56550d3985cda0027f67fe54b808e4' + +$ nix-store --repair-path /nix/store/dj7a81wsm1ijwwpkks3725661h3263p5-glibc-2.13 +fetching path `/nix/store/d7a81wsm1ijwwpkks3725661h3263p5-glibc-2.13'... +… +``` + +# Operation `--dump` + +## Synopsis + +`nix-store` `--dump` *path* + +## Description + +The operation `--dump` produces a NAR (Nix ARchive) file containing the +contents of the file system tree rooted at *path*. The archive is +written to standard output. + +A NAR archive is like a TAR or Zip archive, but it contains only the +information that Nix considers important. For instance, timestamps are +elided because all files in the Nix store have their timestamp set to 0 +anyway. Likewise, all permissions are left out except for the execute +bit, because all files in the Nix store have 444 or 555 permission. + +Also, a NAR archive is *canonical*, meaning that “equal” paths always +produce the same NAR archive. For instance, directory entries are +always sorted so that the actual on-disk order doesn’t influence the +result. This means that the cryptographic hash of a NAR dump of a +path is usable as a fingerprint of the contents of the path. Indeed, +the hashes of store paths stored in Nix’s database (see `nix-store -q +--hash`) are SHA-256 hashes of the NAR dump of each store path. + +NAR archives support filenames of unlimited length and 64-bit file +sizes. They can contain regular files, directories, and symbolic links, +but not other types of files (such as device nodes). + +A Nix archive can be unpacked using `nix-store +--restore`. + +# Operation `--restore` + +## Synopsis + +`nix-store` `--restore` *path* + +## Description + +The operation `--restore` unpacks a NAR archive to *path*, which must +not already exist. The archive is read from standard input. + +# Operation `--export` + +## Synopsis + +`nix-store` `--export` *paths…* + +## Description + +The operation `--export` writes a serialisation of the specified store +paths to standard output in a format that can be imported into another +Nix store with `nix-store --import`. This is like `nix-store +--dump`, except that the NAR archive produced by that command doesn’t +contain the necessary meta-information to allow it to be imported into +another Nix store (namely, the set of references of the path). + +This command does not produce a *closure* of the specified paths, so if +a store path references other store paths that are missing in the target +Nix store, the import will fail. To copy a whole closure, do something +like: + +```console +$ nix-store --export $(nix-store -qR paths) > out +``` + +To import the whole closure again, run: + +```console +$ nix-store --import < out +``` + +# Operation `--import` + +## Synopsis + +`nix-store` `--import` + +## Description + +The operation `--import` reads a serialisation of a set of store paths +produced by `nix-store --export` from standard input and adds those +store paths to the Nix store. Paths that already exist in the Nix store +are ignored. If a path refers to another path that doesn’t exist in the +Nix store, the import fails. + +# Operation `--optimise` + +## Synopsis + +`nix-store` `--optimise` + +## Description + +The operation `--optimise` reduces Nix store disk space usage by finding +identical files in the store and hard-linking them to each other. It +typically reduces the size of the store by something like 25-35%. Only +regular files and symlinks are hard-linked in this manner. Files are +considered identical when they have the same NAR archive serialisation: +that is, regular files must have the same contents and permission +(executable or non-executable), and symlinks must have the same +contents. + +After completion, or when the command is interrupted, a report on the +achieved savings is printed on standard error. + +Use `-vv` or `-vvv` to get some progress indication. + +## Example + +```console +$ nix-store --optimise +hashing files in `/nix/store/qhqx7l2f1kmwihc9bnxs7rc159hsxnf3-gcc-4.1.1' +... +541838819 bytes (516.74 MiB) freed by hard-linking 54143 files; +there are 114486 files with equal contents out of 215894 files in total +``` + +# Operation `--read-log` + +## Synopsis + +`nix-store` {`--read-log` | `-l`} *paths…* + +## Description + +The operation `--read-log` prints the build log of the specified store +paths on standard output. The build log is whatever the builder of a +derivation wrote to standard output and standard error. If a store path +is not a derivation, the deriver of the store path is used. + +Build logs are kept in `/nix/var/log/nix/drvs`. However, there is no +guarantee that a build log is available for any particular store path. +For instance, if the path was downloaded as a pre-built binary through a +substitute, then the log is unavailable. + +## Example + +```console +$ nix-store -l $(which ktorrent) +building /nix/store/dhc73pvzpnzxhdgpimsd9sw39di66ph1-ktorrent-2.2.1 +unpacking sources +unpacking source archive /nix/store/p8n1jpqs27mgkjw07pb5269717nzf5f8-ktorrent-2.2.1.tar.gz +ktorrent-2.2.1/ +ktorrent-2.2.1/NEWS +... +``` + +# Operation `--dump-db` + +## Synopsis + +`nix-store` `--dump-db` [*paths…*] + +## Description + +The operation `--dump-db` writes a dump of the Nix database to standard +output. It can be loaded into an empty Nix store using `--load-db`. This +is useful for making backups and when migrating to different database +schemas. + +By default, `--dump-db` will dump the entire Nix database. When one or +more store paths is passed, only the subset of the Nix database for +those store paths is dumped. As with `--export`, the user is responsible +for passing all the store paths for a closure. See `--export` for an +example. + +# Operation `--load-db` + +## Synopsis + +`nix-store` `--load-db` + +## Description + +The operation `--load-db` reads a dump of the Nix database created by +`--dump-db` from standard input and loads it into the Nix database. + +# Operation `--print-env` + +## Synopsis + +`nix-store` `--print-env` *drvpath* + +## Description + +The operation `--print-env` prints out the environment of a derivation +in a format that can be evaluated by a shell. The command line arguments +of the builder are placed in the variable `_args`. + +## Example + +```console +$ nix-store --print-env $(nix-instantiate '<nixpkgs>' -A firefox) +… +export src; src='/nix/store/plpj7qrwcz94z2psh6fchsi7s8yihc7k-firefox-12.0.source.tar.bz2' +export stdenv; stdenv='/nix/store/7c8asx3yfrg5dg1gzhzyq2236zfgibnn-stdenv' +export system; system='x86_64-linux' +export _args; _args='-e /nix/store/9krlzvny65gdc8s7kpb6lkx8cd02c25c-default-builder.sh' +``` + +# Operation `--generate-binary-cache-key` + +## Synopsis + +`nix-store` `--generate-binary-cache-key` *key-name* *secret-key-file* *public-key-file* + +## Description + +This command generates an [Ed25519 key pair](http://ed25519.cr.yp.to/) +that can be used to create a signed binary cache. It takes three +mandatory parameters: + +1. A key name, such as `cache.example.org-1`, that is used to look up + keys on the client when it verifies signatures. It can be anything, + but it’s suggested to use the host name of your cache (e.g. + `cache.example.org`) with a suffix denoting the number of the key + (to be incremented every time you need to revoke a key). + +2. The file name where the secret key is to be stored. + +3. The file name where the public key is to be stored. diff --git a/doc/manual/src/command-ref/opt-common-syn.md b/doc/manual/src/command-ref/opt-common-syn.md new file mode 100644 index 000000000..b66d318c2 --- /dev/null +++ b/doc/manual/src/command-ref/opt-common-syn.md @@ -0,0 +1,57 @@ +\--help + +\--version + +\--verbose + +\-v + +\--quiet + +\--log-format + +format + +\--no-build-output + +\-Q + +\--max-jobs + +\-j + +number + +\--cores + +number + +\--max-silent-time + +number + +\--timeout + +number + +\--keep-going + +\-k + +\--keep-failed + +\-K + +\--fallback + +\--readonly-mode + +\-I + +path + +\--option + +name + +value diff --git a/doc/manual/src/command-ref/opt-common.md b/doc/manual/src/command-ref/opt-common.md new file mode 100644 index 000000000..9650f53f8 --- /dev/null +++ b/doc/manual/src/command-ref/opt-common.md @@ -0,0 +1,228 @@ +# Common Options + +Most Nix commands accept the following command-line options: + + - `--help` + Prints out a summary of the command syntax and exits. + + - `--version` + Prints out the Nix version number on standard output and exits. + + - `--verbose` / `-v` + Increases the level of verbosity of diagnostic messages printed on + standard error. For each Nix operation, the information printed on + standard output is well-defined; any diagnostic information is + printed on standard error, never on standard output. + + This option may be specified repeatedly. Currently, the following + verbosity levels exist: + + - 0 + “Errors only”: only print messages explaining why the Nix + invocation failed. + + - 1 + “Informational”: print *useful* messages about what Nix is + doing. This is the default. + + - 2 + “Talkative”: print more informational messages. + + - 3 + “Chatty”: print even more informational messages. + + - 4 + “Debug”: print debug information. + + - 5 + “Vomit”: print vast amounts of debug information. + + - `--quiet` + Decreases the level of verbosity of diagnostic messages printed on + standard error. This is the inverse option to `-v` / `--verbose`. + + This option may be specified repeatedly. See the previous verbosity + levels list. + + - `--log-format` *format* + This option can be used to change the output of the log format, with + *format* being one of: + + - raw + This is the raw format, as outputted by nix-build. + + - internal-json + Outputs the logs in a structured manner. + + > **Warning** + > + > While the schema itself is relatively stable, the format of + > the error-messages (namely of the `msg`-field) can change + > between releases. + + - bar + Only display a progress bar during the builds. + + - bar-with-logs + Display the raw logs, with the progress bar at the bottom. + + - `--no-build-output` / `-Q` + By default, output written by builders to standard output and + standard error is echoed to the Nix command's standard error. This + option suppresses this behaviour. Note that the builder's standard + output and error are always written to a log file in + `prefix/nix/var/log/nix`. + + - `--max-jobs` / `-j` *number* + Sets the maximum number of build jobs that Nix will perform in + parallel to the specified number. Specify `auto` to use the number + of CPUs in the system. The default is specified by the `max-jobs` + configuration setting, which itself defaults to `1`. A higher + value is useful on SMP systems or to exploit I/O latency. + + Setting it to `0` disallows building on the local machine, which is + useful when you want builds to happen only on remote builders. + + - `--cores` + Sets the value of the `NIX_BUILD_CORES` environment variable in + the invocation of builders. Builders can use this variable at + their discretion to control the maximum amount of parallelism. For + instance, in Nixpkgs, if the derivation attribute + `enableParallelBuilding` is set to `true`, the builder passes the + `-jN` flag to GNU Make. It defaults to the value of the `cores` + configuration setting, if set, or `1` otherwise. The value `0` + means that the builder should use all available CPU cores in the + system. + + - `--max-silent-time` + Sets the maximum number of seconds that a builder can go without + producing any data on standard output or standard error. The + default is specified by the `max-silent-time` configuration + setting. `0` means no time-out. + + - `--timeout` + Sets the maximum number of seconds that a builder can run. The + default is specified by the `timeout` configuration setting. `0` + means no timeout. + + - `--keep-going` / `-k` + Keep going in case of failed builds, to the greatest extent + possible. That is, if building an input of some derivation fails, + Nix will still build the other inputs, but not the derivation + itself. Without this option, Nix stops if any build fails (except + for builds of substitutes), possibly killing builds in progress (in + case of parallel or distributed builds). + + - `--keep-failed` / `-K` + Specifies that in case of a build failure, the temporary directory + (usually in `/tmp`) in which the build takes place should not be + deleted. The path of the build directory is printed as an + informational message. + + - `--fallback` + Whenever Nix attempts to build a derivation for which substitutes + are known for each output path, but realising the output paths + through the substitutes fails, fall back on building the derivation. + + The most common scenario in which this is useful is when we have + registered substitutes in order to perform binary distribution from, + say, a network repository. If the repository is down, the + realisation of the derivation will fail. When this option is + specified, Nix will build the derivation instead. Thus, installation + from binaries falls back on installation from source. This option is + not the default since it is generally not desirable for a transient + failure in obtaining the substitutes to lead to a full build from + source (with the related consumption of resources). + + - `--no-build-hook` + Disables the build hook mechanism. This allows to ignore remote + builders if they are setup on the machine. + + It's useful in cases where the bandwidth between the client and the + remote builder is too low. In that case it can take more time to + upload the sources to the remote builder and fetch back the result + than to do the computation locally. + + - `--readonly-mode` + When this option is used, no attempt is made to open the Nix + database. Most Nix operations do need database access, so those + operations will fail. + + - `--arg` *name* *value* + This option is accepted by `nix-env`, `nix-instantiate`, + `nix-shell` and `nix-build`. When evaluating Nix expressions, the + expression evaluator will automatically try to call functions that + it encounters. It can automatically call functions for which every + argument has a [default + value](../expressions/language-constructs.md#functions) (e.g., + `{ argName ? defaultValue }: ...`). With `--arg`, you can also + call functions that have arguments without a default value (or + override a default value). That is, if the evaluator encounters a + function with an argument named *name*, it will call it with value + *value*. + + For instance, the top-level `default.nix` in Nixpkgs is actually a + function: + + ```nix + { # The system (e.g., `i686-linux') for which to build the packages. + system ? builtins.currentSystem + ... + }: ... + ``` + + So if you call this Nix expression (e.g., when you do `nix-env -i + pkgname`), the function will be called automatically using the + value [`builtins.currentSystem`](../expressions/builtins.md) for + the `system` argument. You can override this using `--arg`, e.g., + `nix-env -i pkgname --arg system \"i686-freebsd\"`. (Note that + since the argument is a Nix string literal, you have to escape the + quotes.) + + - `--argstr` *name* *value* + This option is like `--arg`, only the value is not a Nix + expression but a string. So instead of `--arg system + \"i686-linux\"` (the outer quotes are to keep the shell happy) you + can say `--argstr system i686-linux`. + + - `--attr` / `-A` *attrPath* + Select an attribute from the top-level Nix expression being + evaluated. (`nix-env`, `nix-instantiate`, `nix-build` and + `nix-shell` only.) The *attribute path* *attrPath* is a sequence + of attribute names separated by dots. For instance, given a + top-level Nix expression *e*, the attribute path `xorg.xorgserver` + would cause the expression `e.xorg.xorgserver` to be used. See + [`nix-env --install`](nix-env.md#operation---install) for some + concrete examples. + + In addition to attribute names, you can also specify array indices. + For instance, the attribute path `foo.3.bar` selects the `bar` + attribute of the fourth element of the array in the `foo` attribute + of the top-level expression. + + - `--expr` / `-E` + Interpret the command line arguments as a list of Nix expressions to + be parsed and evaluated, rather than as a list of file names of Nix + expressions. (`nix-instantiate`, `nix-build` and `nix-shell` only.) + + For `nix-shell`, this option is commonly used to give you a shell in + which you can build the packages returned by the expression. If you + want to get a shell which contain the *built* packages ready for + use, give your expression to the `nix-shell -p` convenience flag + instead. + + - `-I` *path* + Add a path to the Nix expression search path. This option may be + given multiple times. See the `NIX_PATH` environment variable for + information on the semantics of the Nix search path. Paths added + through `-I` take precedence over `NIX_PATH`. + + - `--option` *name* *value* + Set the Nix configuration option *name* to *value*. This overrides + settings in the Nix configuration file (see nix.conf5). + + - `--repair` + Fix corrupted or missing store paths by redownloading or rebuilding + them. Note that this is slow because it requires computing a + cryptographic hash of the contents of every path in the closure of + the build. Also note the warning under `nix-store --repair-path`. diff --git a/doc/manual/src/command-ref/opt-inst-syn.md b/doc/manual/src/command-ref/opt-inst-syn.md new file mode 100644 index 000000000..1703c40e3 --- /dev/null +++ b/doc/manual/src/command-ref/opt-inst-syn.md @@ -0,0 +1,15 @@ +\--prebuilt-only + +\-b + +\--attr + +\-A + +\--from-expression + +\-E + +\--from-profile + +path diff --git a/doc/manual/src/command-ref/utilities.md b/doc/manual/src/command-ref/utilities.md new file mode 100644 index 000000000..5ba8a02a3 --- /dev/null +++ b/doc/manual/src/command-ref/utilities.md @@ -0,0 +1,3 @@ +# Utilities + +This section lists utilities that you can use when you work with Nix. diff --git a/doc/manual/src/expressions/advanced-attributes.md b/doc/manual/src/expressions/advanced-attributes.md new file mode 100644 index 000000000..31ebadda1 --- /dev/null +++ b/doc/manual/src/expressions/advanced-attributes.md @@ -0,0 +1,249 @@ +# Advanced Attributes + +Derivations can declare some infrequently used optional attributes. + + - `allowedReferences` + The optional attribute `allowedReferences` specifies a list of legal + references (dependencies) of the output of the builder. For example, + + ```nix + allowedReferences = []; + ``` + + enforces that the output of a derivation cannot have any runtime + dependencies on its inputs. To allow an output to have a runtime + dependency on itself, use `"out"` as a list item. This is used in + NixOS to check that generated files such as initial ramdisks for + booting Linux don’t have accidental dependencies on other paths in + the Nix store. + + - `allowedRequisites` + This attribute is similar to `allowedReferences`, but it specifies + the legal requisites of the whole closure, so all the dependencies + recursively. For example, + + ```nix + allowedRequisites = [ foobar ]; + ``` + + enforces that the output of a derivation cannot have any other + runtime dependency than `foobar`, and in addition it enforces that + `foobar` itself doesn't introduce any other dependency itself. + + - `disallowedReferences` + The optional attribute `disallowedReferences` specifies a list of + illegal references (dependencies) of the output of the builder. For + example, + + ```nix + disallowedReferences = [ foo ]; + ``` + + enforces that the output of a derivation cannot have a direct + runtime dependencies on the derivation `foo`. + + - `disallowedRequisites` + This attribute is similar to `disallowedReferences`, but it + specifies illegal requisites for the whole closure, so all the + dependencies recursively. For example, + + ```nix + disallowedRequisites = [ foobar ]; + ``` + + enforces that the output of a derivation cannot have any runtime + dependency on `foobar` or any other derivation depending recursively + on `foobar`. + + - `exportReferencesGraph` + This attribute allows builders access to the references graph of + their inputs. The attribute is a list of inputs in the Nix store + whose references graph the builder needs to know. The value of + this attribute should be a list of pairs `[ name1 path1 name2 + path2 ... ]`. The references graph of each *pathN* will be stored + in a text file *nameN* in the temporary build directory. The text + files have the format used by `nix-store --register-validity` + (with the deriver fields left empty). For example, when the + following derivation is built: + + ```nix + derivation { + ... + exportReferencesGraph = [ "libfoo-graph" libfoo ]; + }; + ``` + + the references graph of `libfoo` is placed in the file + `libfoo-graph` in the temporary build directory. + + `exportReferencesGraph` is useful for builders that want to do + something with the closure of a store path. Examples include the + builders in NixOS that generate the initial ramdisk for booting + Linux (a `cpio` archive containing the closure of the boot script) + and the ISO-9660 image for the installation CD (which is populated + with a Nix store containing the closure of a bootable NixOS + configuration). + + - `impureEnvVars` + This attribute allows you to specify a list of environment variables + that should be passed from the environment of the calling user to + the builder. Usually, the environment is cleared completely when the + builder is executed, but with this attribute you can allow specific + environment variables to be passed unmodified. For example, + `fetchurl` in Nixpkgs has the line + + ```nix + impureEnvVars = [ "http_proxy" "https_proxy" ... ]; + ``` + + to make it use the proxy server configuration specified by the user + in the environment variables `http_proxy` and friends. + + This attribute is only allowed in *fixed-output derivations* (see + below), where impurities such as these are okay since (the hash + of) the output is known in advance. It is ignored for all other + derivations. + + > **Warning** + > + > `impureEnvVars` implementation takes environment variables from + > the current builder process. When a daemon is building its + > environmental variables are used. Without the daemon, the + > environmental variables come from the environment of the + > `nix-build`. + + - `outputHash`; `outputHashAlgo`; `outputHashMode` + These attributes declare that the derivation is a so-called + *fixed-output derivation*, which means that a cryptographic hash of + the output is already known in advance. When the build of a + fixed-output derivation finishes, Nix computes the cryptographic + hash of the output and compares it to the hash declared with these + attributes. If there is a mismatch, the build fails. + + The rationale for fixed-output derivations is derivations such as + those produced by the `fetchurl` function. This function downloads a + file from a given URL. To ensure that the downloaded file has not + been modified, the caller must also specify a cryptographic hash of + the file. For example, + + ```nix + fetchurl { + url = "http://ftp.gnu.org/pub/gnu/hello/hello-2.1.1.tar.gz"; + sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465"; + } + ``` + + It sometimes happens that the URL of the file changes, e.g., because + servers are reorganised or no longer available. We then must update + the call to `fetchurl`, e.g., + + ```nix + fetchurl { + url = "ftp://ftp.nluug.nl/pub/gnu/hello/hello-2.1.1.tar.gz"; + sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465"; + } + ``` + + If a `fetchurl` derivation was treated like a normal derivation, the + output paths of the derivation and *all derivations depending on it* + would change. For instance, if we were to change the URL of the + Glibc source distribution in Nixpkgs (a package on which almost all + other packages depend) massive rebuilds would be needed. This is + unfortunate for a change which we know cannot have a real effect as + it propagates upwards through the dependency graph. + + For fixed-output derivations, on the other hand, the name of the + output path only depends on the `outputHash*` and `name` attributes, + while all other attributes are ignored for the purpose of computing + the output path. (The `name` attribute is included because it is + part of the path.) + + As an example, here is the (simplified) Nix expression for + `fetchurl`: + + ```nix + { stdenv, curl }: # The curl program is used for downloading. + + { url, sha256 }: + + stdenv.mkDerivation { + name = baseNameOf (toString url); + builder = ./builder.sh; + buildInputs = [ curl ]; + + # This is a fixed-output derivation; the output must be a regular + # file with SHA256 hash sha256. + outputHashMode = "flat"; + outputHashAlgo = "sha256"; + outputHash = sha256; + + inherit url; + } + ``` + + The `outputHashAlgo` attribute specifies the hash algorithm used to + compute the hash. It can currently be `"sha1"`, `"sha256"` or + `"sha512"`. + + The `outputHashMode` attribute determines how the hash is computed. + It must be one of the following two values: + + - `"flat"` + The output must be a non-executable regular file. If it isn’t, + the build fails. The hash is simply computed over the contents + of that file (so it’s equal to what Unix commands like + `sha256sum` or `sha1sum` produce). + + This is the default. + + - `"recursive"` + The hash is computed over the NAR archive dump of the output + (i.e., the result of [`nix-store + --dump`](../command-ref/nix-store.md#operation---dump)). In + this case, the output can be anything, including a directory + tree. + + The `outputHash` attribute, finally, must be a string containing + the hash in either hexadecimal or base-32 notation. (See the + [`nix-hash` command](../command-ref/nix-hash.md) for information + about converting to and from base-32 notation.) + + - `passAsFile` + A list of names of attributes that should be passed via files rather + than environment variables. For example, if you have + + ```nix + passAsFile = ["big"]; + big = "a very long string"; + ``` + + then when the builder runs, the environment variable `bigPath` + will contain the absolute path to a temporary file containing `a + very long string`. That is, for any attribute *x* listed in + `passAsFile`, Nix will pass an environment variable `xPath` + holding the path of the file containing the value of attribute + *x*. This is useful when you need to pass large strings to a + builder, since most operating systems impose a limit on the size + of the environment (typically, a few hundred kilobyte). + + - `preferLocalBuild` + If this attribute is set to `true` and [distributed building is + enabled](../advanced-topics/distributed-builds.md), then, if + possible, the derivaton will be built locally instead of forwarded + to a remote machine. This is appropriate for trivial builders + where the cost of doing a download or remote build would exceed + the cost of building locally. + + - `allowSubstitutes` + If this attribute is set to `false`, then Nix will always build this + derivation; it will not try to substitute its outputs. This is + useful for very trivial derivations (such as `writeText` in Nixpkgs) + that are cheaper to build than to substitute from a binary cache. + + > **Note** + > + > You need to have a builder configured which satisfies the + > derivation’s `system` attribute, since the derivation cannot be + > substituted. Thus it is usually a good idea to align `system` with + > `builtins.currentSystem` when setting `allowSubstitutes` to + > `false`. For most trivial derivations this should be the case. diff --git a/doc/manual/src/expressions/arguments-variables.md b/doc/manual/src/expressions/arguments-variables.md new file mode 100644 index 000000000..12198c879 --- /dev/null +++ b/doc/manual/src/expressions/arguments-variables.md @@ -0,0 +1,80 @@ +# Arguments and Variables + +The [Nix expression for GNU Hello](expression-syntax.md) is a +function; it is missing some arguments that have to be filled in +somewhere. In the Nix Packages collection this is done in the file +`pkgs/top-level/all-packages.nix`, where all Nix expressions for +packages are imported and called with the appropriate arguments. Here +are some fragments of `all-packages.nix`, with annotations of what +they mean: + +```nix +... + +rec { ① + + hello = import ../applications/misc/hello/ex-1 ② { ③ + inherit fetchurl stdenv perl; + }; + + perl = import ../development/interpreters/perl { ④ + inherit fetchurl stdenv; + }; + + fetchurl = import ../build-support/fetchurl { + inherit stdenv; ... + }; + + stdenv = ...; + +} +``` + +1. This file defines a set of attributes, all of which are concrete + derivations (i.e., not functions). In fact, we define a *mutually + recursive* set of attributes. That is, the attributes can refer to + each other. This is precisely what we want since we want to “plug” + the various packages into each other. + +2. Here we *import* the Nix expression for GNU Hello. The import + operation just loads and returns the specified Nix expression. In + fact, we could just have put the contents of the Nix expression + for GNU Hello in `all-packages.nix` at this point. That would be + completely equivalent, but it would make `all-packages.nix` rather + bulky. + + Note that we refer to `../applications/misc/hello/ex-1`, not + `../applications/misc/hello/ex-1/default.nix`. When you try to + import a directory, Nix automatically appends `/default.nix` to the + file name. + +3. This is where the actual composition takes place. Here we *call* the + function imported from `../applications/misc/hello/ex-1` with a set + containing the things that the function expects, namely `fetchurl`, + `stdenv`, and `perl`. We use inherit again to use the attributes + defined in the surrounding scope (we could also have written + `fetchurl = fetchurl;`, etc.). + + The result of this function call is an actual derivation that can be + built by Nix (since when we fill in the arguments of the function, + what we get is its body, which is the call to `stdenv.mkDerivation` + in the [Nix expression for GNU Hello](expression-syntax.md)). + + > **Note** + > + > Nixpkgs has a convenience function `callPackage` that imports and + > calls a function, filling in any missing arguments by passing the + > corresponding attribute from the Nixpkgs set, like this: + > + > ```nix + > hello = callPackage ../applications/misc/hello/ex-1 { }; + > ``` + > + > If necessary, you can set or override arguments: + > + > ```nix + > hello = callPackage ../applications/misc/hello/ex-1 { stdenv = myStdenv; }; + > ``` + +4. Likewise, we have to instantiate Perl, `fetchurl`, and the standard + environment. diff --git a/doc/manual/src/expressions/build-script.md b/doc/manual/src/expressions/build-script.md new file mode 100644 index 000000000..b1eacae88 --- /dev/null +++ b/doc/manual/src/expressions/build-script.md @@ -0,0 +1,70 @@ +# Build Script + +Here is the builder referenced from Hello's Nix expression (stored in +`pkgs/applications/misc/hello/ex-1/builder.sh`): + +```bash +source $stdenv/setup ① + +PATH=$perl/bin:$PATH ② + +tar xvfz $src ③ +cd hello-* +./configure --prefix=$out ④ +make ⑤ +make install +``` + +The builder can actually be made a lot shorter by using the *generic +builder* functions provided by `stdenv`, but here we write out the build +steps to elucidate what a builder does. It performs the following steps: + +1. When Nix runs a builder, it initially completely clears the + environment (except for the attributes declared in the derivation). + This is done to prevent undeclared inputs from being used in the + build process. If for example the `PATH` contained `/usr/bin`, then + you might accidentally use `/usr/bin/gcc`. + + So the first step is to set up the environment. This is done by + calling the `setup` script of the standard environment. The + environment variable `stdenv` points to the location of the + standard environment being used. (It wasn't specified explicitly + as an attribute in Hello's Nix expression, but `mkDerivation` adds + it automatically.) + +2. Since Hello needs Perl, we have to make sure that Perl is in the + `PATH`. The `perl` environment variable points to the location of + the Perl package (since it was passed in as an attribute to the + derivation), so `$perl/bin` is the directory containing the Perl + interpreter. + +3. Now we have to unpack the sources. The `src` attribute was bound to + the result of fetching the Hello source tarball from the network, so + the `src` environment variable points to the location in the Nix + store to which the tarball was downloaded. After unpacking, we `cd` + to the resulting source directory. + + The whole build is performed in a temporary directory created in + `/tmp`, by the way. This directory is removed after the builder + finishes, so there is no need to clean up the sources afterwards. + Also, the temporary directory is always newly created, so you don't + have to worry about files from previous builds interfering with the + current build. + +4. GNU Hello is a typical Autoconf-based package, so we first have to + run its `configure` script. In Nix every package is stored in a + separate location in the Nix store, for instance + `/nix/store/9a54ba97fb71b65fda531012d0443ce2-hello-2.1.1`. Nix + computes this path by cryptographically hashing all attributes of + the derivation. The path is passed to the builder through the `out` + environment variable. So here we give `configure` the parameter + `--prefix=$out` to cause Hello to be installed in the expected + location. + +5. Finally we build Hello (`make`) and install it into the location + specified by `out` (`make install`). + +If you are wondering about the absence of error checking on the result +of various commands called in the builder: this is because the shell +script is evaluated with Bash's `-e` option, which causes the script to +be aborted if any command fails without an error check. diff --git a/doc/manual/src/expressions/builtin-constants.md b/doc/manual/src/expressions/builtin-constants.md new file mode 100644 index 000000000..3345a715b --- /dev/null +++ b/doc/manual/src/expressions/builtin-constants.md @@ -0,0 +1,20 @@ +# Built-in Constants + +Here are the constants built into the Nix expression evaluator: + + - `builtins` + The set `builtins` contains all the built-in functions and values. + You can use `builtins` to test for the availability of features in + the Nix installation, e.g., + + ```nix + if builtins ? getEnv then builtins.getEnv "PATH" else "" + ``` + + This allows a Nix expression to fall back gracefully on older Nix + installations that don’t have the desired built-in function. + + - `builtins.currentSystem` + The built-in value `currentSystem` evaluates to the Nix platform + identifier for the Nix installation on which the expression is being + evaluated, such as `"i686-linux"` or `"x86_64-darwin"`. diff --git a/doc/manual/src/expressions/builtins-prefix.md b/doc/manual/src/expressions/builtins-prefix.md new file mode 100644 index 000000000..0f7c3d32f --- /dev/null +++ b/doc/manual/src/expressions/builtins-prefix.md @@ -0,0 +1,15 @@ +# Built-in Functions + +This section lists the functions built into the Nix expression +evaluator. (The built-in function `derivation` is discussed above.) +Some built-ins, such as `derivation`, are always in scope of every Nix +expression; you can just access them right away. But to prevent +polluting the namespace too much, most built-ins are not in +scope. Instead, you can access them through the `builtins` built-in +value, which is a set that contains all built-in functions and values. +For instance, `derivation` is also available as `builtins.derivation`. + + - `derivation` *attrs*; `builtins.derivation` *attrs* + + `derivation` is described in [its own section](derivations.md). + diff --git a/doc/manual/src/expressions/derivations.md b/doc/manual/src/expressions/derivations.md new file mode 100644 index 000000000..d26a33b7f --- /dev/null +++ b/doc/manual/src/expressions/derivations.md @@ -0,0 +1,161 @@ +# Derivations + +The most important built-in function is `derivation`, which is used to +describe a single derivation (a build action). It takes as input a set, +the attributes of which specify the inputs of the build. + + - There must be an attribute named `system` whose value must be a + string specifying a Nix system type, such as `"i686-linux"` or + `"x86_64-darwin"`. (To figure out your system type, run `nix -vv + --version`.) The build can only be performed on a machine and + operating system matching the system type. (Nix can automatically + [forward builds for other + platforms](../advanced-topics/distributed-builds.md) by forwarding + them to other machines.) + + - There must be an attribute named `name` whose value must be a + string. This is used as a symbolic name for the package by + `nix-env`, and it is appended to the output paths of the derivation. + + - There must be an attribute named `builder` that identifies the + program that is executed to perform the build. It can be either a + derivation or a source (a local file reference, e.g., + `./builder.sh`). + + - Every attribute is passed as an environment variable to the builder. + Attribute values are translated to environment variables as follows: + + - Strings and numbers are just passed verbatim. + + - A *path* (e.g., `../foo/sources.tar`) causes the referenced file + to be copied to the store; its location in the store is put in + the environment variable. The idea is that all sources should + reside in the Nix store, since all inputs to a derivation should + reside in the Nix store. + + - A *derivation* causes that derivation to be built prior to the + present derivation; its default output path is put in the + environment variable. + + - Lists of the previous types are also allowed. They are simply + concatenated, separated by spaces. + + - `true` is passed as the string `1`, `false` and `null` are + passed as an empty string. + + - The optional attribute `args` specifies command-line arguments to be + passed to the builder. It should be a list. + + - The optional attribute `outputs` specifies a list of symbolic + outputs of the derivation. By default, a derivation produces a + single output path, denoted as `out`. However, derivations can + produce multiple output paths. This is useful because it allows + outputs to be downloaded or garbage-collected separately. For + instance, imagine a library package that provides a dynamic library, + header files, and documentation. A program that links against the + library doesn’t need the header files and documentation at runtime, + and it doesn’t need the documentation at build time. Thus, the + library package could specify: + + ```nix + outputs = [ "lib" "headers" "doc" ]; + ``` + + This will cause Nix to pass environment variables `lib`, `headers` + and `doc` to the builder containing the intended store paths of each + output. The builder would typically do something like + + ```bash + ./configure \ + --libdir=$lib/lib \ + --includedir=$headers/include \ + --docdir=$doc/share/doc + ``` + + for an Autoconf-style package. You can refer to each output of a + derivation by selecting it as an attribute, e.g. + + ```nix + buildInputs = [ pkg.lib pkg.headers ]; + ``` + + The first element of `outputs` determines the *default output*. + Thus, you could also write + + ```nix + buildInputs = [ pkg pkg.headers ]; + ``` + + since `pkg` is equivalent to `pkg.lib`. + +The function `mkDerivation` in the Nixpkgs standard environment is a +wrapper around `derivation` that adds a default value for `system` and +always uses Bash as the builder, to which the supplied builder is passed +as a command-line argument. See the Nixpkgs manual for details. + +The builder is executed as follows: + + - A temporary directory is created under the directory specified by + `TMPDIR` (default `/tmp`) where the build will take place. The + current directory is changed to this directory. + + - The environment is cleared and set to the derivation attributes, as + specified above. + + - In addition, the following variables are set: + + - `NIX_BUILD_TOP` contains the path of the temporary directory for + this build. + + - Also, `TMPDIR`, `TEMPDIR`, `TMP`, `TEMP` are set to point to the + temporary directory. This is to prevent the builder from + accidentally writing temporary files anywhere else. Doing so + might cause interference by other processes. + + - `PATH` is set to `/path-not-set` to prevent shells from + initialising it to their built-in default value. + + - `HOME` is set to `/homeless-shelter` to prevent programs from + using `/etc/passwd` or the like to find the user's home + directory, which could cause impurity. Usually, when `HOME` is + set, it is used as the location of the home directory, even if + it points to a non-existent path. + + - `NIX_STORE` is set to the path of the top-level Nix store + directory (typically, `/nix/store`). + + - For each output declared in `outputs`, the corresponding + environment variable is set to point to the intended path in the + Nix store for that output. Each output path is a concatenation + of the cryptographic hash of all build inputs, the `name` + attribute and the output name. (The output name is omitted if + it’s `out`.) + + - If an output path already exists, it is removed. Also, locks are + acquired to prevent multiple Nix instances from performing the same + build at the same time. + + - A log of the combined standard output and error is written to + `/nix/var/log/nix`. + + - The builder is executed with the arguments specified by the + attribute `args`. If it exits with exit code 0, it is considered to + have succeeded. + + - The temporary directory is removed (unless the `-K` option was + specified). + + - If the build was successful, Nix scans each output path for + references to input paths by looking for the hash parts of the input + paths. Since these are potential runtime dependencies, Nix registers + them as dependencies of the output paths. + + - After the build, Nix sets the last-modified timestamp on all files + in the build result to 1 (00:00:01 1/1/1970 UTC), sets the group to + the default group, and sets the mode of the file to 0444 or 0555 + (i.e., read-only, with execute permission enabled if the file was + originally executable). Note that possible `setuid` and `setgid` + bits are cleared. Setuid and setgid programs are not currently + supported by Nix. This is because the Nix archives used in + deployment have no concept of ownership information, and because it + makes the build result dependent on the user performing the build. diff --git a/doc/manual/src/expressions/expression-language.md b/doc/manual/src/expressions/expression-language.md new file mode 100644 index 000000000..267fcb983 --- /dev/null +++ b/doc/manual/src/expressions/expression-language.md @@ -0,0 +1,12 @@ +# Nix Expression Language + +The Nix expression language is a pure, lazy, functional language. Purity +means that operations in the language don't have side-effects (for +instance, there is no variable assignment). Laziness means that +arguments to functions are evaluated only when they are needed. +Functional means that functions are “normal” values that can be passed +around and manipulated in interesting ways. The language is not a +full-featured, general purpose language. Its main job is to describe +packages, compositions of packages, and the variability within packages. + +This section presents the various features of the language. diff --git a/doc/manual/src/expressions/expression-syntax.md b/doc/manual/src/expressions/expression-syntax.md new file mode 100644 index 000000000..2a1306e32 --- /dev/null +++ b/doc/manual/src/expressions/expression-syntax.md @@ -0,0 +1,93 @@ +# Expression Syntax + +Here is a Nix expression for GNU Hello: + +```nix +{ stdenv, fetchurl, perl }: ① + +stdenv.mkDerivation { ② + name = "hello-2.1.1"; ③ + builder = ./builder.sh; ④ + src = fetchurl { ⑤ + url = "ftp://ftp.nluug.nl/pub/gnu/hello/hello-2.1.1.tar.gz"; + sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465"; + }; + inherit perl; ⑥ +} +``` + +This file is actually already in the Nix Packages collection in +`pkgs/applications/misc/hello/ex-1/default.nix`. It is customary to +place each package in a separate directory and call the single Nix +expression in that directory `default.nix`. The file has the following +elements (referenced from the figure by number): + +1. This states that the expression is a *function* that expects to be + called with three arguments: `stdenv`, `fetchurl`, and `perl`. They + are needed to build Hello, but we don't know how to build them here; + that's why they are function arguments. `stdenv` is a package that + is used by almost all Nix Packages packages; it provides a + “standard” environment consisting of the things you would expect + in a basic Unix environment: a C/C++ compiler (GCC, to be precise), + the Bash shell, fundamental Unix tools such as `cp`, `grep`, `tar`, + etc. `fetchurl` is a function that downloads files. `perl` is the + Perl interpreter. + + Nix functions generally have the form `{ x, y, ..., z }: e` where + `x`, `y`, etc. are the names of the expected arguments, and where + *e* is the body of the function. So here, the entire remainder of + the file is the body of the function; when given the required + arguments, the body should describe how to build an instance of + the Hello package. + +2. So we have to build a package. Building something from other stuff + is called a *derivation* in Nix (as opposed to sources, which are + built by humans instead of computers). We perform a derivation by + calling `stdenv.mkDerivation`. `mkDerivation` is a function + provided by `stdenv` that builds a package from a set of + *attributes*. A set is just a list of key/value pairs where each + key is a string and each value is an arbitrary Nix + expression. They take the general form `{ name1 = expr1; ... + nameN = exprN; }`. + +3. The attribute `name` specifies the symbolic name and version of + the package. Nix doesn't really care about these things, but they + are used by for instance `nix-env -q` to show a “human-readable” + name for packages. This attribute is required by `mkDerivation`. + +4. The attribute `builder` specifies the builder. This attribute can + sometimes be omitted, in which case `mkDerivation` will fill in a + default builder (which does a `configure; make; make install`, in + essence). Hello is sufficiently simple that the default builder + would suffice, but in this case, we will show an actual builder + for educational purposes. The value `./builder.sh` refers to the + shell script shown in the [next section](build-script.md), + discussed below. + +5. The builder has to know what the sources of the package are. Here, + the attribute `src` is bound to the result of a call to the + `fetchurl` function. Given a URL and a SHA-256 hash of the expected + contents of the file at that URL, this function builds a derivation + that downloads the file and checks its hash. So the sources are a + dependency that like all other dependencies is built before Hello + itself is built. + + Instead of `src` any other name could have been used, and in fact + there can be any number of sources (bound to different attributes). + However, `src` is customary, and it's also expected by the default + builder (which we don't use in this example). + +6. Since the derivation requires Perl, we have to pass the value of the + `perl` function argument to the builder. All attributes in the set + are actually passed as environment variables to the builder, so + declaring an attribute + + ```nix + perl = perl; + ``` + + will do the trick: it binds an attribute `perl` to the function + argument which also happens to be called `perl`. However, it looks a + bit silly, so there is a shorter syntax. The `inherit` keyword + causes the specified attributes to be bound to whatever variables + with the same name happen to be in scope. diff --git a/doc/manual/src/expressions/generic-builder.md b/doc/manual/src/expressions/generic-builder.md new file mode 100644 index 000000000..cf26b5f82 --- /dev/null +++ b/doc/manual/src/expressions/generic-builder.md @@ -0,0 +1,66 @@ +# Generic Builder Syntax + +Recall that the [build script for GNU Hello](build-script.md) looked +something like this: + +```bash +PATH=$perl/bin:$PATH +tar xvfz $src +cd hello-* +./configure --prefix=$out +make +make install +``` + +The builders for almost all Unix packages look like this — set up some +environment variables, unpack the sources, configure, build, and +install. For this reason the standard environment provides some Bash +functions that automate the build process. Here is what a builder using +the generic build facilities looks like: + +```bash +buildInputs="$perl" ① + +source $stdenv/setup ② + +genericBuild ③ +``` + +Here is what each line means: + +1. The `buildInputs` variable tells `setup` to use the indicated + packages as “inputs”. This means that if a package provides a `bin` + subdirectory, it's added to `PATH`; if it has a `include` + subdirectory, it's added to GCC's header search path; and so on. + (This is implemented in a modular way: `setup` tries to source the + file `pkg/nix-support/setup-hook` of all dependencies. These “setup + hooks” can then set up whatever environment variables they want; for + instance, the setup hook for Perl sets the `PERL5LIB` environment + variable to contain the `lib/site_perl` directories of all inputs.) + +2. The function `genericBuild` is defined in the file `$stdenv/setup`. + +3. The final step calls the shell function `genericBuild`, which + performs the steps that were done explicitly in the previous build + script. The generic builder is smart enough to figure out whether + to unpack the sources using `gzip`, `bzip2`, etc. It can be + customised in many ways; see the Nixpkgs manual for details. + +Discerning readers will note that the `buildInputs` could just as well +have been set in the Nix expression, like this: + +```nix + buildInputs = [ perl ]; +``` + +The `perl` attribute can then be removed, and the builder becomes even +shorter: + +```bash +source $stdenv/setup +genericBuild +``` + +In fact, `mkDerivation` provides a default builder that looks exactly +like that, so it is actually possible to omit the builder for Hello +entirely. diff --git a/doc/manual/src/expressions/language-constructs.md b/doc/manual/src/expressions/language-constructs.md new file mode 100644 index 000000000..cb0169239 --- /dev/null +++ b/doc/manual/src/expressions/language-constructs.md @@ -0,0 +1,350 @@ +# Language Constructs + +## Recursive sets + +Recursive sets are just normal sets, but the attributes can refer to +each other. For example, + +```nix +rec { + x = y; + y = 123; +}.x +``` + +evaluates to `123`. Note that without `rec` the binding `x = y;` would +refer to the variable `y` in the surrounding scope, if one exists, and +would be invalid if no such variable exists. That is, in a normal +(non-recursive) set, attributes are not added to the lexical scope; in a +recursive set, they are. + +Recursive sets of course introduce the danger of infinite recursion. For +example, the expression + +```nix +rec { + x = y; + y = x; +}.x +``` + +will crash with an `infinite recursion encountered` error message. + +## Let-expressions + +A let-expression allows you to define local variables for an expression. +For instance, + +```nix +let + x = "foo"; + y = "bar"; +in x + y +``` + +evaluates to `"foobar"`. + +## Inheriting attributes + +When defining a set or in a let-expression it is often convenient to +copy variables from the surrounding lexical scope (e.g., when you want +to propagate attributes). This can be shortened using the `inherit` +keyword. For instance, + +```nix +let x = 123; in +{ inherit x; + y = 456; +} +``` + +is equivalent to + +```nix +let x = 123; in +{ x = x; + y = 456; +} +``` + +and both evaluate to `{ x = 123; y = 456; }`. (Note that this works +because `x` is added to the lexical scope by the `let` construct.) It is +also possible to inherit attributes from another set. For instance, in +this fragment from `all-packages.nix`, + +```nix +graphviz = (import ../tools/graphics/graphviz) { + inherit fetchurl stdenv libpng libjpeg expat x11 yacc; + inherit (xlibs) libXaw; +}; + +xlibs = { + libX11 = ...; + libXaw = ...; + ... +} + +libpng = ...; +libjpg = ...; +... +``` + +the set used in the function call to the function defined in +`../tools/graphics/graphviz` inherits a number of variables from the +surrounding scope (`fetchurl` ... `yacc`), but also inherits `libXaw` +(the X Athena Widgets) from the `xlibs` (X11 client-side libraries) set. + +Summarizing the fragment + +```nix +... +inherit x y z; +inherit (src-set) a b c; +... +``` + +is equivalent to + +```nix +... +x = x; y = y; z = z; +a = src-set.a; b = src-set.b; c = src-set.c; +... +``` + +when used while defining local variables in a let-expression or while +defining a set. + +## Functions + +Functions have the following form: + +```nix +pattern: body +``` + +The pattern specifies what the argument of the function must look like, +and binds variables in the body to (parts of) the argument. There are +three kinds of patterns: + + - If a pattern is a single identifier, then the function matches any + argument. Example: + + ```nix + let negate = x: !x; + concat = x: y: x + y; + in if negate true then concat "foo" "bar" else "" + ``` + + Note that `concat` is a function that takes one argument and returns + a function that takes another argument. This allows partial + parameterisation (i.e., only filling some of the arguments of a + function); e.g., + + ```nix + map (concat "foo") [ "bar" "bla" "abc" ] + ``` + + evaluates to `[ "foobar" "foobla" "fooabc" ]`. + + - A *set pattern* of the form `{ name1, name2, …, nameN }` matches a + set containing the listed attributes, and binds the values of those + attributes to variables in the function body. For example, the + function + + ```nix + { x, y, z }: z + y + x + ``` + + can only be called with a set containing exactly the attributes `x`, + `y` and `z`. No other attributes are allowed. If you want to allow + additional arguments, you can use an ellipsis (`...`): + + ```nix + { x, y, z, ... }: z + y + x + ``` + + This works on any set that contains at least the three named + attributes. + + It is possible to provide *default values* for attributes, in + which case they are allowed to be missing. A default value is + specified by writing `name ? e`, where *e* is an arbitrary + expression. For example, + + ```nix + { x, y ? "foo", z ? "bar" }: z + y + x + ``` + + specifies a function that only requires an attribute named `x`, but + optionally accepts `y` and `z`. + + - An `@`-pattern provides a means of referring to the whole value + being matched: + + ```nix + args@{ x, y, z, ... }: z + y + x + args.a + ``` + + but can also be written as: + + ```nix + { x, y, z, ... } @ args: z + y + x + args.a + ``` + + Here `args` is bound to the entire argument, which is further + matched against the pattern `{ x, y, z, + ... }`. `@`-pattern makes mainly sense with an ellipsis(`...`) as + you can access attribute names as `a`, using `args.a`, which was + given as an additional attribute to the function. + + > **Warning** + > + > The `args@` expression is bound to the argument passed to the + > function which means that attributes with defaults that aren't + > explicitly specified in the function call won't cause an + > evaluation error, but won't exist in `args`. + > + > For instance + > + > ```nix + > let + > function = args@{ a ? 23, ... }: args; + > in + > function {} + > ```` + > + > will evaluate to an empty attribute set. + +Note that functions do not have names. If you want to give them a name, +you can bind them to an attribute, e.g., + +```nix +let concat = { x, y }: x + y; +in concat { x = "foo"; y = "bar"; } +``` + +## Conditionals + +Conditionals look like this: + +```nix +if e1 then e2 else e3 +``` + +where *e1* is an expression that should evaluate to a Boolean value +(`true` or `false`). + +## Assertions + +Assertions are generally used to check that certain requirements on or +between features and dependencies hold. They look like this: + +```nix +assert e1; e2 +``` + +where *e1* is an expression that should evaluate to a Boolean value. If +it evaluates to `true`, *e2* is returned; otherwise expression +evaluation is aborted and a backtrace is printed. + +Here is a Nix expression for the Subversion package that shows how +assertions can be used:. + +```nix +{ localServer ? false +, httpServer ? false +, sslSupport ? false +, pythonBindings ? false +, javaSwigBindings ? false +, javahlBindings ? false +, stdenv, fetchurl +, openssl ? null, httpd ? null, db4 ? null, expat, swig ? null, j2sdk ? null +}: + +assert localServer -> db4 != null; ① +assert httpServer -> httpd != null && httpd.expat == expat; ② +assert sslSupport -> openssl != null && (httpServer -> httpd.openssl == openssl); ③ +assert pythonBindings -> swig != null && swig.pythonSupport; +assert javaSwigBindings -> swig != null && swig.javaSupport; +assert javahlBindings -> j2sdk != null; + +stdenv.mkDerivation { + name = "subversion-1.1.1"; + ... + openssl = if sslSupport then openssl else null; ④ + ... +} +``` + +The points of interest are: + +1. This assertion states that if Subversion is to have support for + local repositories, then Berkeley DB is needed. So if the Subversion + function is called with the `localServer` argument set to `true` but + the `db4` argument set to `null`, then the evaluation fails. + +2. This is a more subtle condition: if Subversion is built with Apache + (`httpServer`) support, then the Expat library (an XML library) used + by Subversion should be same as the one used by Apache. This is + because in this configuration Subversion code ends up being linked + with Apache code, and if the Expat libraries do not match, a build- + or runtime link error or incompatibility might occur. + +3. This assertion says that in order for Subversion to have SSL support + (so that it can access `https` URLs), an OpenSSL library must be + passed. Additionally, it says that *if* Apache support is enabled, + then Apache's OpenSSL should match Subversion's. (Note that if + Apache support is not enabled, we don't care about Apache's + OpenSSL.) + +4. The conditional here is not really related to assertions, but is + worth pointing out: it ensures that if SSL support is disabled, then + the Subversion derivation is not dependent on OpenSSL, even if a + non-`null` value was passed. This prevents an unnecessary rebuild of + Subversion if OpenSSL changes. + +## With-expressions + +A *with-expression*, + +```nix +with e1; e2 +``` + +introduces the set *e1* into the lexical scope of the expression *e2*. +For instance, + +```nix +let as = { x = "foo"; y = "bar"; }; +in with as; x + y +``` + +evaluates to `"foobar"` since the `with` adds the `x` and `y` attributes +of `as` to the lexical scope in the expression `x + y`. The most common +use of `with` is in conjunction with the `import` function. E.g., + +```nix +with (import ./definitions.nix); ... +``` + +makes all attributes defined in the file `definitions.nix` available as +if they were defined locally in a `let`-expression. + +The bindings introduced by `with` do not shadow bindings introduced by +other means, e.g. + +```nix +let a = 3; in with { a = 1; }; let a = 4; in with { a = 2; }; ... +``` + +establishes the same scope as + +```nix +let a = 1; in let a = 2; in let a = 3; in let a = 4; in ... +``` + +## Comments + +Comments can be single-line, started with a `#` character, or +inline/multi-line, enclosed within `/* ... */`. diff --git a/doc/manual/src/expressions/language-operators.md b/doc/manual/src/expressions/language-operators.md new file mode 100644 index 000000000..1d787ffe3 --- /dev/null +++ b/doc/manual/src/expressions/language-operators.md @@ -0,0 +1,29 @@ +# Operators + +The table below lists the operators in the Nix expression language, in +order of precedence (from strongest to weakest binding). + +| Name | Syntax | Associativity | Description | Precedence | +| ------------------------ | ----------------------------------- | ------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------- | +| Select | *e* `.` *attrpath* \[ `or` *def* \] | none | Select attribute denoted by the attribute path *attrpath* from set *e*. (An attribute path is a dot-separated list of attribute names.) If the attribute doesn’t exist, return *def* if provided, otherwise abort evaluation. | 1 | +| Application | *e1* *e2* | left | Call function *e1* with argument *e2*. | 2 | +| Arithmetic Negation | `-` *e* | none | Arithmetic negation. | 3 | +| Has Attribute | *e* `?` *attrpath* | none | Test whether set *e* contains the attribute denoted by *attrpath*; return `true` or `false`. | 4 | +| List Concatenation | *e1* `++` *e2* | right | List concatenation. | 5 | +| Multiplication | *e1* `*` *e2*, | left | Arithmetic multiplication. | 6 | +| Division | *e1* `/` *e2* | left | Arithmetic division. | 6 | +| Addition | *e1* `+` *e2* | left | Arithmetic addition. | 7 | +| Subtraction | *e1* `-` *e2* | left | Arithmetic subtraction. | 7 | +| String Concatenation | *string1* `+` *string2* | left | String concatenation. | 7 | +| Not | `!` *e* | none | Boolean negation. | 8 | +| Update | *e1* `//` *e2* | right | Return a set consisting of the attributes in *e1* and *e2* (with the latter taking precedence over the former in case of equally named attributes). | 9 | +| Less Than | *e1* `<` *e2*, | none | Arithmetic comparison. | 10 | +| Less Than or Equal To | *e1* `<=` *e2* | none | Arithmetic comparison. | 10 | +| Greater Than | *e1* `>` *e2* | none | Arithmetic comparison. | 10 | +| Greater Than or Equal To | *e1* `>=` *e2* | none | Arithmetic comparison. | 10 | +| Equality | *e1* `==` *e2* | none | Equality. | 11 | +| Inequality | *e1* `!=` *e2* | none | Inequality. | 11 | +| Logical AND | *e1* `&&` *e2* | left | Logical AND. | 12 | +| Logical OR | *e1* `\|\|` *e2* | left | Logical OR. | 13 | +| Logical Implication | *e1* `->` *e2* | none | Logical implication (equivalent to `!e1 \|\| + e2`). | 14 | diff --git a/doc/manual/src/expressions/language-values.md b/doc/manual/src/expressions/language-values.md new file mode 100644 index 000000000..ce31029cc --- /dev/null +++ b/doc/manual/src/expressions/language-values.md @@ -0,0 +1,244 @@ +# Values + +## Simple Values + +Nix has the following basic data types: + + - *Strings* can be written in three ways. + + The most common way is to enclose the string between double quotes, + e.g., `"foo bar"`. Strings can span multiple lines. The special + characters `"` and `\` and the character sequence `${` must be + escaped by prefixing them with a backslash (`\`). Newlines, carriage + returns and tabs can be written as `\n`, `\r` and `\t`, + respectively. + + You can include the result of an expression into a string by + enclosing it in `${...}`, a feature known as *antiquotation*. The + enclosed expression must evaluate to something that can be coerced + into a string (meaning that it must be a string, a path, or a + derivation). For instance, rather than writing + + ```nix + "--with-freetype2-library=" + freetype + "/lib" + ``` + + (where `freetype` is a derivation), you can instead write the more + natural + + ```nix + "--with-freetype2-library=${freetype}/lib" + ``` + + The latter is automatically translated to the former. A more + complicated example (from the Nix expression for + [Qt](http://www.trolltech.com/products/qt)): + + ```nix + configureFlags = " + -system-zlib -system-libpng -system-libjpeg + ${if openglSupport then "-dlopen-opengl + -L${mesa}/lib -I${mesa}/include + -L${libXmu}/lib -I${libXmu}/include" else ""} + ${if threadSupport then "-thread" else "-no-thread"} + "; + ``` + + Note that Nix expressions and strings can be arbitrarily nested; in + this case the outer string contains various antiquotations that + themselves contain strings (e.g., `"-thread"`), some of which in + turn contain expressions (e.g., `${mesa}`). + + The second way to write string literals is as an *indented string*, + which is enclosed between pairs of *double single-quotes*, like so: + + ```nix + '' + This is the first line. + This is the second line. + This is the third line. + '' + ``` + + This kind of string literal intelligently strips indentation from + the start of each line. To be precise, it strips from each line a + number of spaces equal to the minimal indentation of the string as a + whole (disregarding the indentation of empty lines). For instance, + the first and second line are indented two space, while the third + line is indented four spaces. Thus, two spaces are stripped from + each line, so the resulting string is + + ```nix + "This is the first line.\nThis is the second line.\n This is the third line.\n" + ``` + + Note that the whitespace and newline following the opening `''` is + ignored if there is no non-whitespace text on the initial line. + + Antiquotation (`${expr}`) is supported in indented strings. + + Since `${` and `''` have special meaning in indented strings, you + need a way to quote them. `$` can be escaped by prefixing it with + `''` (that is, two single quotes), i.e., `''$`. `''` can be escaped + by prefixing it with `'`, i.e., `'''`. `$` removes any special + meaning from the following `$`. Linefeed, carriage-return and tab + characters can be written as `''\n`, `''\r`, `''\t`, and `''\` + escapes any other character. + + Indented strings are primarily useful in that they allow multi-line + string literals to follow the indentation of the enclosing Nix + expression, and that less escaping is typically necessary for + strings representing languages such as shell scripts and + configuration files because `''` is much less common than `"`. + Example: + + ```nix + stdenv.mkDerivation { + ... + postInstall = + '' + mkdir $out/bin $out/etc + cp foo $out/bin + echo "Hello World" > $out/etc/foo.conf + ${if enableBar then "cp bar $out/bin" else ""} + ''; + ... + } + ``` + + Finally, as a convenience, *URIs* as defined in appendix B of + [RFC 2396](http://www.ietf.org/rfc/rfc2396.txt) can be written *as + is*, without quotes. For instance, the string + `"http://example.org/foo.tar.bz2"` can also be written as + `http://example.org/foo.tar.bz2`. + + - Numbers, which can be *integers* (like `123`) or *floating point* + (like `123.43` or `.27e13`). + + Numbers are type-compatible: pure integer operations will always + return integers, whereas any operation involving at least one + floating point number will have a floating point number as a result. + + - *Paths*, e.g., `/bin/sh` or `./builder.sh`. A path must contain at + least one slash to be recognised as such. For instance, `builder.sh` + is not a path: it's parsed as an expression that selects the + attribute `sh` from the variable `builder`. If the file name is + relative, i.e., if it does not begin with a slash, it is made + absolute at parse time relative to the directory of the Nix + expression that contained it. For instance, if a Nix expression in + `/foo/bar/bla.nix` refers to `../xyzzy/fnord.nix`, the absolute path + is `/foo/xyzzy/fnord.nix`. + + If the first component of a path is a `~`, it is interpreted as if + the rest of the path were relative to the user's home directory. + e.g. `~/foo` would be equivalent to `/home/edolstra/foo` for a user + whose home directory is `/home/edolstra`. + + Paths can also be specified between angle brackets, e.g. + `<nixpkgs>`. This means that the directories listed in the + environment variable `NIX_PATH` will be searched for the given file + or directory name. + + - *Booleans* with values `true` and `false`. + + - The null value, denoted as `null`. + +## Lists + +Lists are formed by enclosing a whitespace-separated list of values +between square brackets. For example, + +```nix +[ 123 ./foo.nix "abc" (f { x = y; }) ] +``` + +defines a list of four elements, the last being the result of a call to +the function `f`. Note that function calls have to be enclosed in +parentheses. If they had been omitted, e.g., + +```nix +[ 123 ./foo.nix "abc" f { x = y; } ] +``` + +the result would be a list of five elements, the fourth one being a +function and the fifth being a set. + +Note that lists are only lazy in values, and they are strict in length. + +## Sets + +Sets are really the core of the language, since ultimately the Nix +language is all about creating derivations, which are really just sets +of attributes to be passed to build scripts. + +Sets are just a list of name/value pairs (called *attributes*) enclosed +in curly brackets, where each value is an arbitrary expression +terminated by a semicolon. For example: + +```nix +{ x = 123; + text = "Hello"; + y = f { bla = 456; }; +} +``` + +This defines a set with attributes named `x`, `text`, `y`. The order of +the attributes is irrelevant. An attribute name may only occur once. + +Attributes can be selected from a set using the `.` operator. For +instance, + +```nix +{ a = "Foo"; b = "Bar"; }.a +``` + +evaluates to `"Foo"`. It is possible to provide a default value in an +attribute selection using the `or` keyword. For example, + +```nix +{ a = "Foo"; b = "Bar"; }.c or "Xyzzy" +``` + +will evaluate to `"Xyzzy"` because there is no `c` attribute in the set. + +You can use arbitrary double-quoted strings as attribute names: + +```nix +{ "foo ${bar}" = 123; "nix-1.0" = 456; }."foo ${bar}" +``` + +This will evaluate to `123` (Assuming `bar` is antiquotable). In the +case where an attribute name is just a single antiquotation, the quotes +can be dropped: + +```nix +{ foo = 123; }.${bar} or 456 +``` + +This will evaluate to `123` if `bar` evaluates to `"foo"` when coerced +to a string and `456` otherwise (again assuming `bar` is antiquotable). + +In the special case where an attribute name inside of a set declaration +evaluates to `null` (which is normally an error, as `null` is not +antiquotable), that attribute is simply not added to the set: + +```nix +{ ${if foo then "bar" else null} = true; } +``` + +This will evaluate to `{}` if `foo` evaluates to `false`. + +A set that has a `__functor` attribute whose value is callable (i.e. is +itself a function or a set with a `__functor` attribute whose value is +callable) can be applied as if it were a function, with the set itself +passed in first , e.g., + +```nix +let add = { __functor = self: x: x + self.x; }; + inc = add // { x = 1; }; +in inc 1 +``` + +evaluates to `2`. This can be used to attach metadata to a function +without the caller needing to treat it specially, or to implement a form +of object-oriented programming, for example. diff --git a/doc/manual/src/expressions/simple-building-testing.md b/doc/manual/src/expressions/simple-building-testing.md new file mode 100644 index 000000000..6f730a936 --- /dev/null +++ b/doc/manual/src/expressions/simple-building-testing.md @@ -0,0 +1,61 @@ +# Building and Testing + +You can now try to build Hello. Of course, you could do `nix-env -i +hello`, but you may not want to install a possibly broken package just +yet. The best way to test the package is by using the command +`nix-build`, which builds a Nix expression and creates a symlink named +`result` in the current directory: + +```console +$ nix-build -A hello +building path `/nix/store/632d2b22514d...-hello-2.1.1' +hello-2.1.1/ +hello-2.1.1/intl/ +hello-2.1.1/intl/ChangeLog +... + +$ ls -l result +lrwxrwxrwx ... 2006-09-29 10:43 result -> /nix/store/632d2b22514d...-hello-2.1.1 + +$ ./result/bin/hello +Hello, world! +``` + +The `-A` option selects the `hello` attribute. This is faster than +using the symbolic package name specified by the `name` attribute +(which also happens to be `hello`) and is unambiguous (there can be +multiple packages with the symbolic name `hello`, but there can be +only one attribute in a set named `hello`). + +`nix-build` registers the `./result` symlink as a garbage collection +root, so unless and until you delete the `./result` symlink, the output +of the build will be safely kept on your system. You can use +`nix-build`’s `-o` switch to give the symlink another name. + +Nix has transactional semantics. Once a build finishes successfully, Nix +makes a note of this in its database: it registers that the path denoted +by `out` is now “valid”. If you try to build the derivation again, Nix +will see that the path is already valid and finish immediately. If a +build fails, either because it returns a non-zero exit code, because Nix +or the builder are killed, or because the machine crashes, then the +output paths will not be registered as valid. If you try to build the +derivation again, Nix will remove the output paths if they exist (e.g., +because the builder died half-way through `make +install`) and try again. Note that there is no “negative caching”: Nix +doesn't remember that a build failed, and so a failed build can always +be repeated. This is because Nix cannot distinguish between permanent +failures (e.g., a compiler error due to a syntax error in the source) +and transient failures (e.g., a disk full condition). + +Nix also performs locking. If you run multiple Nix builds +simultaneously, and they try to build the same derivation, the first Nix +instance that gets there will perform the build, while the others block +(or perform other derivations if available) until the build finishes: + +```console +$ nix-build -A hello +waiting for lock on `/nix/store/0h5b7hp8d4hqfrw8igvx97x1xawrjnac-hello-2.1.1x' +``` + +So it is always safe to run multiple instances of Nix in parallel (which +isn’t the case with, say, `make`). diff --git a/doc/manual/src/expressions/simple-expression.md b/doc/manual/src/expressions/simple-expression.md new file mode 100644 index 000000000..857f71b9b --- /dev/null +++ b/doc/manual/src/expressions/simple-expression.md @@ -0,0 +1,23 @@ +# A Simple Nix Expression + +This section shows how to add and test the [GNU Hello +package](http://www.gnu.org/software/hello/hello.html) to the Nix +Packages collection. Hello is a program that prints out the text “Hello, +world\!”. + +To add a package to the Nix Packages collection, you generally need to +do three things: + +1. Write a Nix expression for the package. This is a file that + describes all the inputs involved in building the package, such as + dependencies, sources, and so on. + +2. Write a *builder*. This is a shell script that builds the package + from the inputs. (In fact, it can be written in any language, but + typically it's a `bash` shell script.) + +3. Add the package to the file `pkgs/top-level/all-packages.nix`. The + Nix expression written in the first step is a *function*; it + requires other packages in order to build it. In this step you put + it all together, i.e., you call the function with the right + arguments to build the actual package. diff --git a/doc/manual/src/expressions/writing-nix-expressions.md b/doc/manual/src/expressions/writing-nix-expressions.md new file mode 100644 index 000000000..5664108e7 --- /dev/null +++ b/doc/manual/src/expressions/writing-nix-expressions.md @@ -0,0 +1,12 @@ +This chapter shows you how to write Nix expressions, which instruct Nix +how to build packages. It starts with a simple example (a Nix expression +for GNU Hello), and then moves on to a more in-depth look at the Nix +expression language. + +> **Note** +> +> This chapter is mostly about the Nix expression language. For more +> extensive information on adding packages to the Nix Packages +> collection (such as functions in the standard environment and coding +> conventions), please consult [its +> manual](http://nixos.org/nixpkgs/manual/). diff --git a/doc/manual/src/figures/user-environments.png b/doc/manual/src/figures/user-environments.png Binary files differnew file mode 100644 index 000000000..1f781cf23 --- /dev/null +++ b/doc/manual/src/figures/user-environments.png diff --git a/doc/manual/src/figures/user-environments.sxd b/doc/manual/src/figures/user-environments.sxd Binary files differnew file mode 100644 index 000000000..bc661b640 --- /dev/null +++ b/doc/manual/src/figures/user-environments.sxd diff --git a/doc/manual/src/glossary.md b/doc/manual/src/glossary.md new file mode 100644 index 000000000..56af9cd85 --- /dev/null +++ b/doc/manual/src/glossary.md @@ -0,0 +1,100 @@ +# Glossary + + - derivation + A description of a build action. The result of a derivation is a + store object. Derivations are typically specified in Nix expressions + using the [`derivation` primitive](expressions/derivations.md). These are + translated into low-level *store derivations* (implicitly by + `nix-env` and `nix-build`, or explicitly by `nix-instantiate`). + + - store + The location in the file system where store objects live. Typically + `/nix/store`. + + - store path + The location in the file system of a store object, i.e., an + immediate child of the Nix store directory. + + - store object + A file that is an immediate child of the Nix store directory. These + can be regular files, but also entire directory trees. Store objects + can be sources (objects copied from outside of the store), + derivation outputs (objects produced by running a build action), or + derivations (files describing a build action). + + - substitute + A substitute is a command invocation stored in the Nix database that + describes how to build a store object, bypassing the normal build + mechanism (i.e., derivations). Typically, the substitute builds the + store object by downloading a pre-built version of the store object + from some server. + + - purity + The assumption that equal Nix derivations when run always produce + the same output. This cannot be guaranteed in general (e.g., a + builder can rely on external inputs such as the network or the + system time) but the Nix model assumes it. + + - Nix expression + A high-level description of software packages and compositions + thereof. Deploying software using Nix entails writing Nix + expressions for your packages. Nix expressions are translated to + derivations that are stored in the Nix store. These derivations can + then be built. + + - reference + A store path `P` is said to have a reference to a store path `Q` if + the store object at `P` contains the path `Q` somewhere. The + *references* of a store path are the set of store paths to which it + has a reference. + + A derivation can reference other derivations and sources (but not + output paths), whereas an output path only references other output + paths. + + - reachable + A store path `Q` is reachable from another store path `P` if `Q` + is in the *closure* of the *references* relation. + + - closure + The closure of a store path is the set of store paths that are + directly or indirectly “reachable” from that store path; that is, + it’s the closure of the path under the *references* relation. For + a package, the closure of its derivation is equivalent to the + build-time dependencies, while the closure of its output path is + equivalent to its runtime dependencies. For correct deployment it + is necessary to deploy whole closures, since otherwise at runtime + files could be missing. The command `nix-store -qR` prints out + closures of store paths. + + As an example, if the store object at path `P` contains a reference + to path `Q`, then `Q` is in the closure of `P`. Further, if `Q` + references `R` then `R` is also in the closure of `P`. + + - output path + A store path produced by a derivation. + + - deriver + The deriver of an *output path* is the store + derivation that built it. + + - validity + A store path is considered *valid* if it exists in the file system, + is listed in the Nix database as being valid, and if all paths in + its closure are also valid. + + - user environment + An automatically generated store object that consists of a set of + symlinks to “active” applications, i.e., other store paths. These + are generated automatically by + [`nix-env`](command-ref/nix-env.md). See *profiles*. + + - profile + A symlink to the current *user environment* of a user, e.g., + `/nix/var/nix/profiles/default`. + + - NAR + A *N*ix *AR*chive. This is a serialisation of a path in the Nix + store. It can contain regular files, directories and symbolic + links. NARs are generated and unpacked using `nix-store --dump` + and `nix-store --restore`. diff --git a/doc/manual/src/hacking.md b/doc/manual/src/hacking.md new file mode 100644 index 000000000..9049e42bb --- /dev/null +++ b/doc/manual/src/hacking.md @@ -0,0 +1,71 @@ +# Hacking + +This section provides some notes on how to hack on Nix. To get the +latest version of Nix from GitHub: + +```console +$ git clone https://github.com/NixOS/nix.git +$ cd nix +``` + +To build Nix for the current operating system/architecture use + +```console +$ nix-build +``` + +or if you have a flake-enabled nix: + +```console +$ nix build +``` + +This will build `defaultPackage` attribute defined in the `flake.nix` +file. To build for other platforms add one of the following suffixes to +it: aarch64-linux, i686-linux, x86\_64-darwin, x86\_64-linux. i.e. + +```console +$ nix-build -A defaultPackage.x86_64-linux +``` + +To build all dependencies and start a shell in which all environment +variables are set up so that those dependencies can be found: + +```console +$ nix-shell +``` + +To build Nix itself in this shell: + +```console +[nix-shell]$ ./bootstrap.sh +[nix-shell]$ ./configure $configureFlags +[nix-shell]$ make -j $NIX_BUILD_CORES +``` + +To install it in `$(pwd)/inst` and test it: + +```console +[nix-shell]$ make install +[nix-shell]$ make installcheck +[nix-shell]$ ./inst/bin/nix --version +nix (Nix) 2.4 +``` + +To run a functional test: + +```console +make tests/test-name-should-auto-complete.sh.test +``` + +If you have a flakes-enabled Nix you can replace: + +```console +$ nix-shell +``` + +by: + +```console +$ nix develop +``` diff --git a/doc/manual/src/installation/building-source.md b/doc/manual/src/installation/building-source.md new file mode 100644 index 000000000..d21a51a82 --- /dev/null +++ b/doc/manual/src/installation/building-source.md @@ -0,0 +1,38 @@ +# Building Nix from Source + +After unpacking or checking out the Nix sources, issue the following +commands: + +```console +$ ./configure options... +$ make +$ make install +``` + +Nix requires GNU Make so you may need to invoke `gmake` instead. + +When building from the Git repository, these should be preceded by the +command: + +```console +$ ./bootstrap.sh +``` + +The installation path can be specified by passing the `--prefix=prefix` +to `configure`. The default installation directory is `/usr/local`. You +can change this to any location you like. You must have write permission +to the *prefix* path. + +Nix keeps its *store* (the place where packages are stored) in +`/nix/store` by default. This can be changed using +`--with-store-dir=path`. + +> **Warning** +> +> It is best *not* to change the Nix store from its default, since doing +> so makes it impossible to use pre-built binaries from the standard +> Nixpkgs channels — that is, all packages will need to be built from +> source. + +Nix keeps state (such as its database and log files) in `/nix/var` by +default. This can be changed using `--localstatedir=path`. diff --git a/doc/manual/src/installation/env-variables.md b/doc/manual/src/installation/env-variables.md new file mode 100644 index 000000000..4a49897e4 --- /dev/null +++ b/doc/manual/src/installation/env-variables.md @@ -0,0 +1,64 @@ +# Environment Variables + +To use Nix, some environment variables should be set. In particular, +`PATH` should contain the directories `prefix/bin` and +`~/.nix-profile/bin`. The first directory contains the Nix tools +themselves, while `~/.nix-profile` is a symbolic link to the current +*user environment* (an automatically generated package consisting of +symlinks to installed packages). The simplest way to set the required +environment variables is to include the file +`prefix/etc/profile.d/nix.sh` in your `~/.profile` (or similar), like +this: + +```bash +source prefix/etc/profile.d/nix.sh +``` + +# `NIX_SSL_CERT_FILE` + +If you need to specify a custom certificate bundle to account for an +HTTPS-intercepting man in the middle proxy, you must specify the path to +the certificate bundle in the environment variable `NIX_SSL_CERT_FILE`. + +If you don't specify a `NIX_SSL_CERT_FILE` manually, Nix will install +and use its own certificate bundle. + +Set the environment variable and install Nix + +```console +$ export NIX_SSL_CERT_FILE=/etc/ssl/my-certificate-bundle.crt +$ sh <(curl -L https://nixos.org/nix/install) +``` + +In the shell profile and rc files (for example, `/etc/bashrc`, +`/etc/zshrc`), add the following line: + +```bash +export NIX_SSL_CERT_FILE=/etc/ssl/my-certificate-bundle.crt +``` + +> **Note** +> +> You must not add the export and then do the install, as the Nix +> installer will detect the presense of Nix configuration, and abort. + +## `NIX_SSL_CERT_FILE` with macOS and the Nix daemon + +On macOS you must specify the environment variable for the Nix daemon +service, then restart it: + +```console +$ sudo launchctl setenv NIX_SSL_CERT_FILE /etc/ssl/my-certificate-bundle.crt +$ sudo launchctl kickstart -k system/org.nixos.nix-daemon +``` + +## Proxy Environment Variables + +The Nix installer has special handling for these proxy-related +environment variables: `http_proxy`, `https_proxy`, `ftp_proxy`, +`no_proxy`, `HTTP_PROXY`, `HTTPS_PROXY`, `FTP_PROXY`, `NO_PROXY`. + +If any of these variables are set when running the Nix installer, then +the installer will create an override file at +`/etc/systemd/system/nix-daemon.service.d/override.conf` so `nix-daemon` +will use them. diff --git a/doc/manual/src/installation/installation.md b/doc/manual/src/installation/installation.md new file mode 100644 index 000000000..b40c5b95f --- /dev/null +++ b/doc/manual/src/installation/installation.md @@ -0,0 +1,2 @@ +This section describes how to install and configure Nix for first-time +use. diff --git a/doc/manual/src/installation/installing-binary.md b/doc/manual/src/installation/installing-binary.md new file mode 100644 index 000000000..8b8d1d738 --- /dev/null +++ b/doc/manual/src/installation/installing-binary.md @@ -0,0 +1,291 @@ +# Installing a Binary Distribution + +If you are using Linux or macOS versions up to 10.14 (Mojave), the +easiest way to install Nix is to run the following command: + +```console +$ sh <(curl -L https://nixos.org/nix/install) +``` + +If you're using macOS 10.15 (Catalina) or newer, consult [the macOS +installation instructions](#macos-installation) before installing. + +As of Nix 2.1.0, the Nix installer will always default to creating a +single-user installation, however opting in to the multi-user +installation is highly recommended. + +# Single User Installation + +To explicitly select a single-user installation on your system: + +```console +$ sh <(curl -L https://nixos.org/nix/install) --no-daemon +``` + +This will perform a single-user installation of Nix, meaning that `/nix` +is owned by the invoking user. You should run this under your usual user +account, *not* as root. The script will invoke `sudo` to create `/nix` +if it doesn’t already exist. If you don’t have `sudo`, you should +manually create `/nix` first as root, e.g.: + +```console +$ mkdir /nix +$ chown alice /nix +``` + +The install script will modify the first writable file from amongst +`.bash_profile`, `.bash_login` and `.profile` to source +`~/.nix-profile/etc/profile.d/nix.sh`. You can set the +`NIX_INSTALLER_NO_MODIFY_PROFILE` environment variable before executing +the install script to disable this behaviour. + +You can uninstall Nix simply by running: + +```console +$ rm -rf /nix +``` + +# Multi User Installation + +The multi-user Nix installation creates system users, and a system +service for the Nix daemon. + + - Linux running systemd, with SELinux disabled + + - macOS + +You can instruct the installer to perform a multi-user installation on +your system: + +```console +$ sh <(curl -L https://nixos.org/nix/install) --daemon +``` + +The multi-user installation of Nix will create build users between the +user IDs 30001 and 30032, and a group with the group ID 30000. You +should run this under your usual user account, *not* as root. The script +will invoke `sudo` as needed. + +> **Note** +> +> If you need Nix to use a different group ID or user ID set, you will +> have to download the tarball manually and [edit the install +> script](#installing-from-a-binary-tarball). + +The installer will modify `/etc/bashrc`, and `/etc/zshrc` if they exist. +The installer will first back up these files with a `.backup-before-nix` +extension. The installer will also create `/etc/profile.d/nix.sh`. + +You can uninstall Nix with the following commands: + +```console +sudo rm -rf /etc/profile/nix.sh /etc/nix /nix ~root/.nix-profile ~root/.nix-defexpr ~root/.nix-channels ~/.nix-profile ~/.nix-defexpr ~/.nix-channels + +# If you are on Linux with systemd, you will need to run: +sudo systemctl stop nix-daemon.socket +sudo systemctl stop nix-daemon.service +sudo systemctl disable nix-daemon.socket +sudo systemctl disable nix-daemon.service +sudo systemctl daemon-reload + +# If you are on macOS, you will need to run: +sudo launchctl unload /Library/LaunchDaemons/org.nixos.nix-daemon.plist +sudo rm /Library/LaunchDaemons/org.nixos.nix-daemon.plist +``` + +There may also be references to Nix in `/etc/profile`, `/etc/bashrc`, +and `/etc/zshrc` which you may remove. + +# macOS Installation + +Starting with macOS 10.15 (Catalina), the root filesystem is read-only. +This means `/nix` can no longer live on your system volume, and that +you'll need a workaround to install Nix. + +The recommended approach, which creates an unencrypted APFS volume for +your Nix store and a "synthetic" empty directory to mount it over at +`/nix`, is least likely to impair Nix or your system. + +> **Note** +> +> With all separate-volume approaches, it's possible something on your +> system (particularly daemons/services and restored apps) may need +> access to your Nix store before the volume is mounted. Adding +> additional encryption makes this more likely. + +If you're using a recent Mac with a [T2 +chip](https://www.apple.com/euro/mac/shared/docs/Apple_T2_Security_Chip_Overview.pdf), +your drive will still be encrypted at rest (in which case "unencrypted" +is a bit of a misnomer). To use this approach, just install Nix with: + +```console +$ sh <(curl -L https://nixos.org/nix/install) --darwin-use-unencrypted-nix-store-volume +``` + +If you don't like the sound of this, you'll want to weigh the other +approaches and tradeoffs detailed in this section. + +> **Note** +> +> All of the known workarounds have drawbacks, but we hope better +> solutions will be available in the future. Some that we have our eye +> on are: +> +> 1. A true firmlink would enable the Nix store to live on the primary +> data volume without the build problems caused by the symlink +> approach. End users cannot currently create true firmlinks. +> +> 2. If the Nix store volume shared FileVault encryption with the +> primary data volume (probably by using the same volume group and +> role), FileVault encryption could be easily supported by the +> installer without requiring manual setup by each user. + +## Change the Nix store path prefix + +Changing the default prefix for the Nix store is a simple approach which +enables you to leave it on your root volume, where it can take full +advantage of FileVault encryption if enabled. Unfortunately, this +approach also opts your device out of some benefits that are enabled by +using the same prefix across systems: + + - Your system won't be able to take advantage of the binary cache + (unless someone is able to stand up and support duplicate caching + infrastructure), which means you'll spend more time waiting for + builds. + + - It's harder to build and deploy packages to Linux systems. + +It would also possible (and often requested) to just apply this change +ecosystem-wide, but it's an intrusive process that has side effects we +want to avoid for now. + +## Use a separate encrypted volume + +If you like, you can also add encryption to the recommended approach +taken by the installer. You can do this by pre-creating an encrypted +volume before you run the installer--or you can run the installer and +encrypt the volume it creates later. + +In either case, adding encryption to a second volume isn't quite as +simple as enabling FileVault for your boot volume. Before you dive in, +there are a few things to weigh: + +1. The additional volume won't be encrypted with your existing + FileVault key, so you'll need another mechanism to decrypt the + volume. + +2. You can store the password in Keychain to automatically decrypt the + volume on boot--but it'll have to wait on Keychain and may not mount + before your GUI apps restore. If any of your launchd agents or apps + depend on Nix-installed software (for example, if you use a + Nix-installed login shell), the restore may fail or break. + + On a case-by-case basis, you may be able to work around this problem + by using `wait4path` to block execution until your executable is + available. + + It's also possible to decrypt and mount the volume earlier with a + login hook--but this mechanism appears to be deprecated and its + future is unclear. + +3. You can hard-code the password in the clear, so that your store + volume can be decrypted before Keychain is available. + +If you are comfortable navigating these tradeoffs, you can encrypt the +volume with something along the lines of: + +```console +alice$ diskutil apfs enableFileVault /nix -user disk +``` + +## Symlink the Nix store to a custom location + +Another simple approach is using `/etc/synthetic.conf` to symlink the +Nix store to the data volume. This option also enables your store to +share any configured FileVault encryption. Unfortunately, builds that +resolve the symlink may leak the canonical path or even fail. + +Because of these downsides, we can't recommend this approach. + +## Notes on the recommended approach + +This section goes into a little more detail on the recommended approach. +You don't need to understand it to run the installer, but it can serve +as a helpful reference if you run into trouble. + +1. In order to compose user-writable locations into the new read-only + system root, Apple introduced a new concept called `firmlinks`, + which it describes as a "bi-directional wormhole" between two + filesystems. You can see the current firmlinks in + `/usr/share/firmlinks`. Unfortunately, firmlinks aren't (currently?) + user-configurable. + + For special cases like NFS mount points or package manager roots, + [synthetic.conf(5)](https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man5/synthetic.conf.5.html) + supports limited user-controlled file-creation (of symlinks, and + synthetic empty directories) at `/`. To create a synthetic empty + directory for mounting at `/nix`, add the following line to + `/etc/synthetic.conf` (create it if necessary): + + nix + +2. This configuration is applied at boot time, but you can use + `apfs.util` to trigger creation (not deletion) of new entries + without a reboot: + + ```console + alice$ /System/Library/Filesystems/apfs.fs/Contents/Resources/apfs.util -B + ``` + +3. Create the new APFS volume with diskutil: + + ```console + alice$ sudo diskutil apfs addVolume diskX APFS 'Nix Store' -mountpoint /nix + ``` + +4. Using `vifs`, add the new mount to `/etc/fstab`. If it doesn't + already have other entries, it should look something like: + + # + # Warning - this file should only be modified with vifs(8) + # + # Failure to do so is unsupported and may be destructive. + # + LABEL=Nix\040Store /nix apfs rw,nobrowse + + The nobrowse setting will keep Spotlight from indexing this volume, + and keep it from showing up on your desktop. + +# Installing a pinned Nix version from a URL + +NixOS.org hosts version-specific installation URLs for all Nix versions +since 1.11.16, at `https://releases.nixos.org/nix/nix-version/install`. + +These install scripts can be used the same as the main NixOS.org +installation script: + +```console +$ sh <(curl -L https://nixos.org/nix/install) +``` + +In the same directory of the install script are sha256 sums, and gpg +signature files. + +# Installing from a binary tarball + +You can also download a binary tarball that contains Nix and all its +dependencies. (This is what the install script at +<https://nixos.org/nix/install> does automatically.) You should unpack +it somewhere (e.g. in `/tmp`), and then run the script named `install` +inside the binary tarball: + +```console +alice$ cd /tmp +alice$ tar xfj nix-1.8-x86_64-darwin.tar.bz2 +alice$ cd nix-1.8-x86_64-darwin +alice$ ./install +``` + +If you need to edit the multi-user installation script to use different +group ID or a different user ID range, modify the variables set in the +file named `install-multi-user`. diff --git a/doc/manual/src/installation/installing-source.md b/doc/manual/src/installation/installing-source.md new file mode 100644 index 000000000..e52d38a03 --- /dev/null +++ b/doc/manual/src/installation/installing-source.md @@ -0,0 +1,4 @@ +# Installing Nix from Source + +If no binary package is available, you can download and compile a source +distribution. diff --git a/doc/manual/src/installation/multi-user.md b/doc/manual/src/installation/multi-user.md new file mode 100644 index 000000000..6920591c4 --- /dev/null +++ b/doc/manual/src/installation/multi-user.md @@ -0,0 +1,77 @@ +# Multi-User Mode + +To allow a Nix store to be shared safely among multiple users, it is +important that users are not able to run builders that modify the Nix +store or database in arbitrary ways, or that interfere with builds +started by other users. If they could do so, they could install a Trojan +horse in some package and compromise the accounts of other users. + +To prevent this, the Nix store and database are owned by some privileged +user (usually `root`) and builders are executed under special user +accounts (usually named `nixbld1`, `nixbld2`, etc.). When a unprivileged +user runs a Nix command, actions that operate on the Nix store (such as +builds) are forwarded to a *Nix daemon* running under the owner of the +Nix store/database that performs the operation. + +> **Note** +> +> Multi-user mode has one important limitation: only root and a set of +> trusted users specified in `nix.conf` can specify arbitrary binary +> caches. So while unprivileged users may install packages from +> arbitrary Nix expressions, they may not get pre-built binaries. + +## Setting up the build users + +The *build users* are the special UIDs under which builds are performed. +They should all be members of the *build users group* `nixbld`. This +group should have no other members. The build users should not be +members of any other group. On Linux, you can create the group and users +as follows: + +```console +$ groupadd -r nixbld +$ for n in $(seq 1 10); do useradd -c "Nix build user $n" \ + -d /var/empty -g nixbld -G nixbld -M -N -r -s "$(which nologin)" \ + nixbld$n; done +``` + +This creates 10 build users. There can never be more concurrent builds +than the number of build users, so you may want to increase this if you +expect to do many builds at the same time. + +## Running the daemon + +The [Nix daemon](../command-ref/nix-daemon.md) should be started as +follows (as `root`): + +```console +$ nix-daemon +``` + +You’ll want to put that line somewhere in your system’s boot scripts. + +To let unprivileged users use the daemon, they should set the +[`NIX_REMOTE` environment variable](../command-ref/env-common.md) to +`daemon`. So you should put a line like + +```console +export NIX_REMOTE=daemon +``` + +into the users’ login scripts. + +## Restricting access + +To limit which users can perform Nix operations, you can use the +permissions on the directory `/nix/var/nix/daemon-socket`. For instance, +if you want to restrict the use of Nix to the members of a group called +`nix-users`, do + +```console +$ chgrp nix-users /nix/var/nix/daemon-socket +$ chmod ug=rwx,o= /nix/var/nix/daemon-socket +``` + +This way, users who are not in the `nix-users` group cannot connect to +the Unix domain socket `/nix/var/nix/daemon-socket/socket`, so they +cannot perform Nix operations. diff --git a/doc/manual/src/installation/nix-security.md b/doc/manual/src/installation/nix-security.md new file mode 100644 index 000000000..1e9036b68 --- /dev/null +++ b/doc/manual/src/installation/nix-security.md @@ -0,0 +1,15 @@ +# Security + +Nix has two basic security models. First, it can be used in “single-user +mode”, which is similar to what most other package management tools do: +there is a single user (typically root) who performs all package +management operations. All other users can then use the installed +packages, but they cannot perform package management operations +themselves. + +Alternatively, you can configure Nix in “multi-user mode”. In this +model, all users can perform package management operations — for +instance, every user can install software without requiring root +privileges. Nix ensures that this is secure. For instance, it’s not +possible for one user to overwrite a package used by another user with a +Trojan horse. diff --git a/doc/manual/src/installation/obtaining-source.md b/doc/manual/src/installation/obtaining-source.md new file mode 100644 index 000000000..0a906e390 --- /dev/null +++ b/doc/manual/src/installation/obtaining-source.md @@ -0,0 +1,18 @@ +# Obtaining a Source Distribution + +The source tarball of the most recent stable release can be downloaded +from the [Nix homepage](http://nixos.org/nix/download.html). You can +also grab the [most recent development +release](http://hydra.nixos.org/job/nix/master/release/latest-finished#tabs-constituents). + +Alternatively, the most recent sources of Nix can be obtained from its +[Git repository](https://github.com/NixOS/nix). For example, the +following command will check out the latest revision into a directory +called `nix`: + +```console +$ git clone https://github.com/NixOS/nix +``` + +Likewise, specific releases can be obtained from the +[tags](https://github.com/NixOS/nix/tags) of the repository. diff --git a/doc/manual/src/installation/prerequisites-source.md b/doc/manual/src/installation/prerequisites-source.md new file mode 100644 index 000000000..69b7c5a5e --- /dev/null +++ b/doc/manual/src/installation/prerequisites-source.md @@ -0,0 +1,71 @@ +# Prerequisites + + - GNU Autoconf (<https://www.gnu.org/software/autoconf/>) and the + autoconf-archive macro collection + (<https://www.gnu.org/software/autoconf-archive/>). These are only + needed to run the bootstrap script, and are not necessary if your + source distribution came with a pre-built `./configure` script. + + - GNU Make. + + - Bash Shell. The `./configure` script relies on bashisms, so Bash is + required. + + - A version of GCC or Clang that supports C++17. + + - `pkg-config` to locate dependencies. If your distribution does not + provide it, you can get it from + <http://www.freedesktop.org/wiki/Software/pkg-config>. + + - The OpenSSL library to calculate cryptographic hashes. If your + distribution does not provide it, you can get it from + <https://www.openssl.org>. + + - The `libbrotlienc` and `libbrotlidec` libraries to provide + implementation of the Brotli compression algorithm. They are + available for download from the official repository + <https://github.com/google/brotli>. + + - The bzip2 compressor program and the `libbz2` library. Thus you must + have bzip2 installed, including development headers and libraries. + If your distribution does not provide these, you can obtain bzip2 + from + <https://web.archive.org/web/20180624184756/http://www.bzip.org/>. + + - `liblzma`, which is provided by XZ Utils. If your distribution does + not provide this, you can get it from <https://tukaani.org/xz/>. + + - cURL and its library. If your distribution does not provide it, you + can get it from <https://curl.haxx.se/>. + + - The SQLite embedded database library, version 3.6.19 or higher. If + your distribution does not provide it, please install it from + <http://www.sqlite.org/>. + + - The [Boehm garbage collector](http://www.hboehm.info/gc/) to reduce + the evaluator’s memory consumption (optional). To enable it, install + `pkgconfig` and the Boehm garbage collector, and pass the flag + `--enable-gc` to `configure`. + + - The `boost` library of version 1.66.0 or higher. It can be obtained + from the official web site <https://www.boost.org/>. + + - The `editline` library of version 1.14.0 or higher. It can be + obtained from the its repository + <https://github.com/troglobit/editline>. + + - Recent versions of Bison and Flex to build the parser. (This is + because Nix needs GLR support in Bison and reentrancy support in + Flex.) For Bison, you need version 2.6, which can be obtained from + the [GNU FTP server](ftp://alpha.gnu.org/pub/gnu/bison). For Flex, + you need version 2.5.35, which is available on + [SourceForge](http://lex.sourceforge.net/). Slightly older versions + may also work, but ancient versions like the ubiquitous 2.5.4a + won't. Note that these are only required if you modify the parser or + when you are building from the Git repository. + + - The `libseccomp` is used to provide syscall filtering on Linux. This + is an optional dependency and can be disabled passing a + `--disable-seccomp-sandboxing` option to the `configure` script (Not + recommended unless your system doesn't support `libseccomp`). To get + the library, visit <https://github.com/seccomp/libseccomp>. diff --git a/doc/manual/src/installation/single-user.md b/doc/manual/src/installation/single-user.md new file mode 100644 index 000000000..f9a3b26ed --- /dev/null +++ b/doc/manual/src/installation/single-user.md @@ -0,0 +1,9 @@ +# Single-User Mode + +In single-user mode, all Nix operations that access the database in +`prefix/var/nix/db` or modify the Nix store in `prefix/store` must be +performed under the user ID that owns those directories. This is +typically root. (If you install from RPM packages, that’s in fact the +default ownership.) However, on single-user machines, it is often +convenient to `chown` those directories to your normal user account so +that you don’t have to `su` to root all the time. diff --git a/doc/manual/src/installation/supported-platforms.md b/doc/manual/src/installation/supported-platforms.md new file mode 100644 index 000000000..8ef1f0e78 --- /dev/null +++ b/doc/manual/src/installation/supported-platforms.md @@ -0,0 +1,7 @@ +# Supported Platforms + +Nix is currently supported on the following platforms: + + - Linux (i686, x86\_64, aarch64). + + - macOS (x86\_64). diff --git a/doc/manual/src/installation/upgrading.md b/doc/manual/src/installation/upgrading.md new file mode 100644 index 000000000..24efc4681 --- /dev/null +++ b/doc/manual/src/installation/upgrading.md @@ -0,0 +1,14 @@ +# Upgrading Nix + +Multi-user Nix users on macOS can upgrade Nix by running: `sudo -i sh -c +'nix-channel --update && +nix-env -iA nixpkgs.nix && +launchctl remove org.nixos.nix-daemon && +launchctl load /Library/LaunchDaemons/org.nixos.nix-daemon.plist'` + +Single-user installations of Nix should run this: `nix-channel --update; +nix-env -iA nixpkgs.nix nixpkgs.cacert` + +Multi-user Nix users on Linux should run this with sudo: `nix-channel +--update; nix-env -iA nixpkgs.nix nixpkgs.cacert; systemctl +daemon-reload; systemctl restart nix-daemon` diff --git a/doc/manual/src/introduction.md b/doc/manual/src/introduction.md new file mode 100644 index 000000000..f01fe7b38 --- /dev/null +++ b/doc/manual/src/introduction.md @@ -0,0 +1,193 @@ +# Introduction + +Nix is a _purely functional package manager_. This means that it +treats packages like values in purely functional programming languages +such as Haskell — they are built by functions that don’t have +side-effects, and they never change after they have been built. Nix +stores packages in the _Nix store_, usually the directory +`/nix/store`, where each package has its own unique subdirectory such +as + + /nix/store/b6gvzjyb2pg0kjfwrjmg1vfhh54ad73z-firefox-33.1/ + +where `b6gvzjyb2pg0…` is a unique identifier for the package that +captures all its dependencies (it’s a cryptographic hash of the +package’s build dependency graph). This enables many powerful +features. + +## Multiple versions + +You can have multiple versions or variants of a package +installed at the same time. This is especially important when +different applications have dependencies on different versions of the +same package — it prevents the “DLL hell”. Because of the hashing +scheme, different versions of a package end up in different paths in +the Nix store, so they don’t interfere with each other. + +An important consequence is that operations like upgrading or +uninstalling an application cannot break other applications, since +these operations never “destructively” update or delete files that are +used by other packages. + +## Complete dependencies + +Nix helps you make sure that package dependency specifications are +complete. In general, when you’re making a package for a package +management system like RPM, you have to specify for each package what +its dependencies are, but there are no guarantees that this +specification is complete. If you forget a dependency, then the +package will build and work correctly on _your_ machine if you have +the dependency installed, but not on the end user's machine if it's +not there. + +Since Nix on the other hand doesn’t install packages in “global” +locations like `/usr/bin` but in package-specific directories, the +risk of incomplete dependencies is greatly reduced. This is because +tools such as compilers don’t search in per-packages directories such +as `/nix/store/5lbfaxb722zp…-openssl-0.9.8d/include`, so if a package +builds correctly on your system, this is because you specified the +dependency explicitly. This takes care of the build-time dependencies. + +Once a package is built, runtime dependencies are found by scanning +binaries for the hash parts of Nix store paths (such as `r8vvq9kq…`). +This sounds risky, but it works extremely well. + +## Multi-user support + +Nix has multi-user support. This means that non-privileged users can +securely install software. Each user can have a different _profile_, +a set of packages in the Nix store that appear in the user’s `PATH`. +If a user installs a package that another user has already installed +previously, the package won’t be built or downloaded a second time. +At the same time, it is not possible for one user to inject a Trojan +horse into a package that might be used by another user. + +## Atomic upgrades and rollbacks + +Since package management operations never overwrite packages in the +Nix store but just add new versions in different paths, they are +_atomic_. So during a package upgrade, there is no time window in +which the package has some files from the old version and some files +from the new version — which would be bad because a program might well +crash if it’s started during that period. + +And since packages aren’t overwritten, the old versions are still +there after an upgrade. This means that you can _roll back_ to the +old version: + +```console +$ nix-env --upgrade some-packages +$ nix-env --rollback +``` + +## Garbage collection + +When you uninstall a package like this… + +```console +$ nix-env --uninstall firefox +``` + +the package isn’t deleted from the system right away (after all, you +might want to do a rollback, or it might be in the profiles of other +users). Instead, unused packages can be deleted safely by running the +_garbage collector_: + +```console +$ nix-collect-garbage +``` + +This deletes all packages that aren’t in use by any user profile or by +a currently running program. + +## Functional package language + +Packages are built from _Nix expressions_, which is a simple +functional language. A Nix expression describes everything that goes +into a package build action (a “derivation”): other packages, sources, +the build script, environment variables for the build script, etc. +Nix tries very hard to ensure that Nix expressions are +_deterministic_: building a Nix expression twice should yield the same +result. + +Because it’s a functional language, it’s easy to support +building variants of a package: turn the Nix expression into a +function and call it any number of times with the appropriate +arguments. Due to the hashing scheme, variants don’t conflict with +each other in the Nix store. + +## Transparent source/binary deployment + +Nix expressions generally describe how to build a package from +source, so an installation action like + +```console +$ nix-env --install firefox +``` + +_could_ cause quite a bit of build activity, as not only Firefox but +also all its dependencies (all the way up to the C library and the +compiler) would have to built, at least if they are not already in the +Nix store. This is a _source deployment model_. For most users, +building from source is not very pleasant as it takes far too long. +However, Nix can automatically skip building from source and instead +use a _binary cache_, a web server that provides pre-built +binaries. For instance, when asked to build +`/nix/store/b6gvzjyb2pg0…-firefox-33.1` from source, Nix would first +check if the file `https://cache.nixos.org/b6gvzjyb2pg0….narinfo` +exists, and if so, fetch the pre-built binary referenced from there; +otherwise, it would fall back to building from source. + +## Nix Packages collection + +We provide a large set of Nix expressions containing hundreds of +existing Unix packages, the _Nix Packages collection_ (Nixpkgs). + +## Managing build environments + +Nix is extremely useful for developers as it makes it easy to +automatically set up the build environment for a package. Given a Nix +expression that describes the dependencies of your package, the +command `nix-shell` will build or download those dependencies if +they’re not already in your Nix store, and then start a Bash shell in +which all necessary environment variables (such as compiler search +paths) are set. + +For example, the following command gets all dependencies of the +Pan newsreader, as described by [its +Nix expression](https://github.com/NixOS/nixpkgs/blob/master/pkgs/applications/networking/newsreaders/pan/default.nix): + +```console +$ nix-shell '<nixpkgs>' -A pan +``` + +You’re then dropped into a shell where you can edit, build and test +the package: + +```console +[nix-shell]$ tar xf $src +[nix-shell]$ cd pan-* +[nix-shell]$ ./configure +[nix-shell]$ make +[nix-shell]$ ./pan/gui/pan +``` + +## Portability + +Nix runs on Linux and macOS. + +## NixOS + +NixOS is a Linux distribution based on Nix. It uses Nix not just for +package management but also to manage the system configuration (e.g., +to build configuration files in `/etc`). This means, among other +things, that it is easy to roll back the entire configuration of the +system to an earlier state. Also, users can install software without +root privileges. For more information and downloads, see the [NixOS +homepage](https://nixos.org/). + +## License + +Nix is released under the terms of the [GNU LGPLv2.1 or (at your +option) any later +version](http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html). diff --git a/doc/manual/src/package-management/basic-package-mgmt.md b/doc/manual/src/package-management/basic-package-mgmt.md new file mode 100644 index 000000000..9702a29eb --- /dev/null +++ b/doc/manual/src/package-management/basic-package-mgmt.md @@ -0,0 +1,172 @@ +# Basic Package Management + +The main command for package management is +[`nix-env`](../command-ref/nix-env.md). You can use it to install, +upgrade, and erase packages, and to query what packages are installed +or are available for installation. + +In Nix, different users can have different “views” on the set of +installed applications. That is, there might be lots of applications +present on the system (possibly in many different versions), but users +can have a specific selection of those active — where “active” just +means that it appears in a directory in the user’s `PATH`. Such a view +on the set of installed applications is called a *user environment*, +which is just a directory tree consisting of symlinks to the files of +the active applications. + +Components are installed from a set of *Nix expressions* that tell Nix +how to build those packages, including, if necessary, their +dependencies. There is a collection of Nix expressions called the +Nixpkgs package collection that contains packages ranging from basic +development stuff such as GCC and Glibc, to end-user applications like +Mozilla Firefox. (Nix is however not tied to the Nixpkgs package +collection; you could write your own Nix expressions based on Nixpkgs, +or completely new ones.) + +You can manually download the latest version of Nixpkgs from +<http://nixos.org/nixpkgs/download.html>. However, it’s much more +convenient to use the Nixpkgs [*channel*](channels.md), since it makes +it easy to stay up to date with new versions of Nixpkgs. Nixpkgs is +automatically added to your list of “subscribed” channels when you +install Nix. If this is not the case for some reason, you can add it +as follows: + +```console +$ nix-channel --add https://nixos.org/channels/nixpkgs-unstable +$ nix-channel --update +``` + +> **Note** +> +> On NixOS, you’re automatically subscribed to a NixOS channel +> corresponding to your NixOS major release (e.g. +> <http://nixos.org/channels/nixos-14.12>). A NixOS channel is identical +> to the Nixpkgs channel, except that it contains only Linux binaries +> and is updated only if a set of regression tests succeed. + +You can view the set of available packages in Nixpkgs: + +```console +$ nix-env -qa +aterm-2.2 +bash-3.0 +binutils-2.15 +bison-1.875d +blackdown-1.4.2 +bzip2-1.0.2 +… +``` + +The flag `-q` specifies a query operation, and `-a` means that you want +to show the “available” (i.e., installable) packages, as opposed to the +installed packages. If you downloaded Nixpkgs yourself, or if you +checked it out from GitHub, then you need to pass the path to your +Nixpkgs tree using the `-f` flag: + +```console +$ nix-env -qaf /path/to/nixpkgs +``` + +where */path/to/nixpkgs* is where you’ve unpacked or checked out +Nixpkgs. + +You can select specific packages by name: + +```console +$ nix-env -qa firefox +firefox-34.0.5 +firefox-with-plugins-34.0.5 +``` + +and using regular expressions: + +```console +$ nix-env -qa 'firefox.*' +``` + +It is also possible to see the *status* of available packages, i.e., +whether they are installed into the user environment and/or present in +the system: + +```console +$ nix-env -qas +… +-PS bash-3.0 +--S binutils-2.15 +IPS bison-1.875d +… +``` + +The first character (`I`) indicates whether the package is installed in +your current user environment. The second (`P`) indicates whether it is +present on your system (in which case installing it into your user +environment would be a very quick operation). The last one (`S`) +indicates whether there is a so-called *substitute* for the package, +which is Nix’s mechanism for doing binary deployment. It just means that +Nix knows that it can fetch a pre-built package from somewhere +(typically a network server) instead of building it locally. + +You can install a package using `nix-env -i`. For instance, + +```console +$ nix-env -i subversion +``` + +will install the package called `subversion` (which is, of course, the +[Subversion version management system](http://subversion.tigris.org/)). + +> **Note** +> +> When you ask Nix to install a package, it will first try to get it in +> pre-compiled form from a *binary cache*. By default, Nix will use the +> binary cache <https://cache.nixos.org>; it contains binaries for most +> packages in Nixpkgs. Only if no binary is available in the binary +> cache, Nix will build the package from source. So if `nix-env +> -i subversion` results in Nix building stuff from source, then either +> the package is not built for your platform by the Nixpkgs build +> servers, or your version of Nixpkgs is too old or too new. For +> instance, if you have a very recent checkout of Nixpkgs, then the +> Nixpkgs build servers may not have had a chance to build everything +> and upload the resulting binaries to <https://cache.nixos.org>. The +> Nixpkgs channel is only updated after all binaries have been uploaded +> to the cache, so if you stick to the Nixpkgs channel (rather than +> using a Git checkout of the Nixpkgs tree), you will get binaries for +> most packages. + +Naturally, packages can also be uninstalled: + +```console +$ nix-env -e subversion +``` + +Upgrading to a new version is just as easy. If you have a new release of +Nix Packages, you can do: + +```console +$ nix-env -u subversion +``` + +This will *only* upgrade Subversion if there is a “newer” version in the +new set of Nix expressions, as defined by some pretty arbitrary rules +regarding ordering of version numbers (which generally do what you’d +expect of them). To just unconditionally replace Subversion with +whatever version is in the Nix expressions, use `-i` instead of `-u`; +`-i` will remove whatever version is already installed. + +You can also upgrade all packages for which there are newer versions: + +```console +$ nix-env -u +``` + +Sometimes it’s useful to be able to ask what `nix-env` would do, without +actually doing it. For instance, to find out what packages would be +upgraded by `nix-env -u`, you can do + +```console +$ nix-env -u --dry-run +(dry run; not doing anything) +upgrading `libxslt-1.1.0' to `libxslt-1.1.10' +upgrading `graphviz-1.10' to `graphviz-1.12' +upgrading `coreutils-5.0' to `coreutils-5.2.1' +``` diff --git a/doc/manual/src/package-management/binary-cache-substituter.md b/doc/manual/src/package-management/binary-cache-substituter.md new file mode 100644 index 000000000..bdc5038fc --- /dev/null +++ b/doc/manual/src/package-management/binary-cache-substituter.md @@ -0,0 +1,50 @@ +# Serving a Nix store via HTTP + +You can easily share the Nix store of a machine via HTTP. This allows +other machines to fetch store paths from that machine to speed up +installations. It uses the same *binary cache* mechanism that Nix +usually uses to fetch pre-built binaries from <https://cache.nixos.org>. + +The daemon that handles binary cache requests via HTTP, `nix-serve`, is +not part of the Nix distribution, but you can install it from Nixpkgs: + +```console +$ nix-env -i nix-serve +``` + +You can then start the server, listening for HTTP connections on +whatever port you like: + +```console +$ nix-serve -p 8080 +``` + +To check whether it works, try the following on the client: + +```console +$ curl http://avalon:8080/nix-cache-info +``` + +which should print something like: + + StoreDir: /nix/store + WantMassQuery: 1 + Priority: 30 + +On the client side, you can tell Nix to use your binary cache using +`--option extra-binary-caches`, e.g.: + +```console +$ nix-env -i firefox --option extra-binary-caches http://avalon:8080/ +``` + +The option `extra-binary-caches` tells Nix to use this binary cache in +addition to your default caches, such as <https://cache.nixos.org>. +Thus, for any path in the closure of Firefox, Nix will first check if +the path is available on the server `avalon` or another binary caches. +If not, it will fall back to building from source. + +You can also tell Nix to always use your binary cache by adding a line +to the `nix.conf` configuration file like this: + + binary-caches = http://avalon:8080/ https://cache.nixos.org/ diff --git a/doc/manual/src/package-management/channels.md b/doc/manual/src/package-management/channels.md new file mode 100644 index 000000000..93c8b41a6 --- /dev/null +++ b/doc/manual/src/package-management/channels.md @@ -0,0 +1,50 @@ +# Channels + +If you want to stay up to date with a set of packages, it’s not very +convenient to manually download the latest set of Nix expressions for +those packages and upgrade using `nix-env`. Fortunately, there’s a +better way: *Nix channels*. + +A Nix channel is just a URL that points to a place that contains a set +of Nix expressions and a manifest. Using the command +[`nix-channel`](../command-ref/nix-channel.md) you can automatically +stay up to date with whatever is available at that URL. + +To see the list of official NixOS channels, visit +<https://nixos.org/channels>. + +You can “subscribe” to a channel using `nix-channel --add`, e.g., + +```console +$ nix-channel --add https://nixos.org/channels/nixpkgs-unstable +``` + +subscribes you to a channel that always contains that latest version of +the Nix Packages collection. (Subscribing really just means that the URL +is added to the file `~/.nix-channels`, where it is read by subsequent +calls to `nix-channel +--update`.) You can “unsubscribe” using `nix-channel +--remove`: + +```console +$ nix-channel --remove nixpkgs +``` + +To obtain the latest Nix expressions available in a channel, do + +```console +$ nix-channel --update +``` + +This downloads and unpacks the Nix expressions in every channel +(downloaded from `url/nixexprs.tar.bz2`). It also makes the union of +each channel’s Nix expressions available by default to `nix-env` +operations (via the symlink `~/.nix-defexpr/channels`). Consequently, +you can then say + +```console +$ nix-env -u +``` + +to upgrade all packages in your profile to the latest versions available +in the subscribed channels. diff --git a/doc/manual/src/package-management/copy-closure.md b/doc/manual/src/package-management/copy-closure.md new file mode 100644 index 000000000..d3fac4d76 --- /dev/null +++ b/doc/manual/src/package-management/copy-closure.md @@ -0,0 +1,34 @@ +# Copying Closures via SSH + +The command `nix-copy-closure` copies a Nix store path along with all +its dependencies to or from another machine via the SSH protocol. It +doesn’t copy store paths that are already present on the target machine. +For example, the following command copies Firefox with all its +dependencies: + + $ nix-copy-closure --to alice@itchy.example.org $(type -p firefox) + +See the [manpage for `nix-copy-closure`](../command-ref/nix-copy-closure.md) for details. + +With `nix-store +--export` and `nix-store --import` you can write the closure of a store +path (that is, the path and all its dependencies) to a file, and then +unpack that file into another Nix store. For example, + + $ nix-store --export $(nix-store -qR $(type -p firefox)) > firefox.closure + +writes the closure of Firefox to a file. You can then copy this file to +another machine and install the closure: + + $ nix-store --import < firefox.closure + +Any store paths in the closure that are already present in the target +store are ignored. It is also possible to pipe the export into another +command, e.g. to copy and install a closure directly to/on another +machine: + + $ nix-store --export $(nix-store -qR $(type -p firefox)) | bzip2 | \ + ssh alice@itchy.example.org "bunzip2 | nix-store --import" + +However, `nix-copy-closure` is generally more efficient because it only +copies paths that are not already present in the target Nix store. diff --git a/doc/manual/src/package-management/garbage-collection.md b/doc/manual/src/package-management/garbage-collection.md new file mode 100644 index 000000000..fecb30fd6 --- /dev/null +++ b/doc/manual/src/package-management/garbage-collection.md @@ -0,0 +1,73 @@ +# Garbage Collection + +`nix-env` operations such as upgrades (`-u`) and uninstall (`-e`) never +actually delete packages from the system. All they do (as shown above) +is to create a new user environment that no longer contains symlinks to +the “deleted” packages. + +Of course, since disk space is not infinite, unused packages should be +removed at some point. You can do this by running the Nix garbage +collector. It will remove from the Nix store any package not used +(directly or indirectly) by any generation of any profile. + +Note however that as long as old generations reference a package, it +will not be deleted. After all, we wouldn’t be able to do a rollback +otherwise. So in order for garbage collection to be effective, you +should also delete (some) old generations. Of course, this should only +be done if you are certain that you will not need to roll back. + +To delete all old (non-current) generations of your current profile: + +```console +$ nix-env --delete-generations old +``` + +Instead of `old` you can also specify a list of generations, e.g., + +```console +$ nix-env --delete-generations 10 11 14 +``` + +To delete all generations older than a specified number of days (except +the current generation), use the `d` suffix. For example, + +```console +$ nix-env --delete-generations 14d +``` + +deletes all generations older than two weeks. + +After removing appropriate old generations you can run the garbage +collector as follows: + +```console +$ nix-store --gc +``` + +The behaviour of the gargage collector is affected by the +`keep-derivations` (default: true) and `keep-outputs` (default: false) +options in the Nix configuration file. The defaults will ensure that all +derivations that are build-time dependencies of garbage collector roots +will be kept and that all output paths that are runtime dependencies +will be kept as well. All other derivations or paths will be collected. +(This is usually what you want, but while you are developing it may make +sense to keep outputs to ensure that rebuild times are quick.) If you +are feeling uncertain, you can also first view what files would be +deleted: + +```console +$ nix-store --gc --print-dead +``` + +Likewise, the option `--print-live` will show the paths that *won’t* be +deleted. + +There is also a convenient little utility `nix-collect-garbage`, which +when invoked with the `-d` (`--delete-old`) switch deletes all old +generations of all profiles in `/nix/var/nix/profiles`. So + +```console +$ nix-collect-garbage -d +``` + +is a quick and easy way to clean up your system. diff --git a/doc/manual/src/package-management/garbage-collector-roots.md b/doc/manual/src/package-management/garbage-collector-roots.md new file mode 100644 index 000000000..30c5b7f8d --- /dev/null +++ b/doc/manual/src/package-management/garbage-collector-roots.md @@ -0,0 +1,18 @@ +# Garbage Collector Roots + +The roots of the garbage collector are all store paths to which there +are symlinks in the directory `prefix/nix/var/nix/gcroots`. For +instance, the following command makes the path +`/nix/store/d718ef...-foo` a root of the collector: + +```console +$ ln -s /nix/store/d718ef...-foo /nix/var/nix/gcroots/bar +``` + +That is, after this command, the garbage collector will not remove +`/nix/store/d718ef...-foo` or any of its dependencies. + +Subdirectories of `prefix/nix/var/nix/gcroots` are also searched for +symlinks. Symlinks to non-store paths are followed and searched for +roots, but symlinks to non-store paths *inside* the paths reached in +that way are not followed to prevent infinite recursion. diff --git a/doc/manual/src/package-management/package-management.md b/doc/manual/src/package-management/package-management.md new file mode 100644 index 000000000..bd26a09ab --- /dev/null +++ b/doc/manual/src/package-management/package-management.md @@ -0,0 +1,5 @@ +This chapter discusses how to do package management with Nix, i.e., +how to obtain, install, upgrade, and erase packages. This is the +“user’s” perspective of the Nix system — people who want to *create* +packages should consult the [chapter on writing Nix +expressions](../expressions/writing-nix-expressions.md). diff --git a/doc/manual/src/package-management/profiles.md b/doc/manual/src/package-management/profiles.md new file mode 100644 index 000000000..fbbfb7320 --- /dev/null +++ b/doc/manual/src/package-management/profiles.md @@ -0,0 +1,133 @@ +# Profiles + +Profiles and user environments are Nix’s mechanism for implementing the +ability to allow different users to have different configurations, and +to do atomic upgrades and rollbacks. To understand how they work, it’s +useful to know a bit about how Nix works. In Nix, packages are stored in +unique locations in the *Nix store* (typically, `/nix/store`). For +instance, a particular version of the Subversion package might be stored +in a directory +`/nix/store/dpmvp969yhdqs7lm2r1a3gng7pyq6vy4-subversion-1.1.3/`, while +another version might be stored in +`/nix/store/5mq2jcn36ldlmh93yj1n8s9c95pj7c5s-subversion-1.1.2`. The long +strings prefixed to the directory names are cryptographic hashes (to be +precise, 160-bit truncations of SHA-256 hashes encoded in a base-32 +notation) of *all* inputs involved in building the package — sources, +dependencies, compiler flags, and so on. So if two packages differ in +any way, they end up in different locations in the file system, so they +don’t interfere with each other. Here is what a part of a typical Nix +store looks like: + + + +Of course, you wouldn’t want to type + +```console +$ /nix/store/dpmvp969yhdq...-subversion-1.1.3/bin/svn +``` + +every time you want to run Subversion. Of course we could set up the +`PATH` environment variable to include the `bin` directory of every +package we want to use, but this is not very convenient since changing +`PATH` doesn’t take effect for already existing processes. The solution +Nix uses is to create directory trees of symlinks to *activated* +packages. These are called *user environments* and they are packages +themselves (though automatically generated by `nix-env`), so they too +reside in the Nix store. For instance, in the figure above, the user +environment `/nix/store/0c1p5z4kda11...-user-env` contains a symlink to +just Subversion 1.1.2 (arrows in the figure indicate symlinks). This +would be what we would obtain if we had done + +```console +$ nix-env -i subversion +``` + +on a set of Nix expressions that contained Subversion 1.1.2. + +This doesn’t in itself solve the problem, of course; you wouldn’t want +to type `/nix/store/0c1p5z4kda11...-user-env/bin/svn` either. That’s why +there are symlinks outside of the store that point to the user +environments in the store; for instance, the symlinks `default-42-link` +and `default-43-link` in the example. These are called *generations* +since every time you perform a `nix-env` operation, a new user +environment is generated based on the current one. For instance, +generation 43 was created from generation 42 when we did + +```console +$ nix-env -i subversion firefox +``` + +on a set of Nix expressions that contained Firefox and a new version of +Subversion. + +Generations are grouped together into *profiles* so that different users +don’t interfere with each other if they don’t want to. For example: + +```console +$ ls -l /nix/var/nix/profiles/ +... +lrwxrwxrwx 1 eelco ... default-42-link -> /nix/store/0c1p5z4kda11...-user-env +lrwxrwxrwx 1 eelco ... default-43-link -> /nix/store/3aw2pdyx2jfc...-user-env +lrwxrwxrwx 1 eelco ... default -> default-43-link +``` + +This shows a profile called `default`. The file `default` itself is +actually a symlink that points to the current generation. When we do a +`nix-env` operation, a new user environment and generation link are +created based on the current one, and finally the `default` symlink is +made to point at the new generation. This last step is atomic on Unix, +which explains how we can do atomic upgrades. (Note that the +building/installing of new packages doesn’t interfere in any way with +old packages, since they are stored in different locations in the Nix +store.) + +If you find that you want to undo a `nix-env` operation, you can just do + +```console +$ nix-env --rollback +``` + +which will just make the current generation link point at the previous +link. E.g., `default` would be made to point at `default-42-link`. You +can also switch to a specific generation: + +```console +$ nix-env --switch-generation 43 +``` + +which in this example would roll forward to generation 43 again. You can +also see all available generations: + +```console +$ nix-env --list-generations +``` + +You generally wouldn’t have `/nix/var/nix/profiles/some-profile/bin` in +your `PATH`. Rather, there is a symlink `~/.nix-profile` that points to +your current profile. This means that you should put +`~/.nix-profile/bin` in your `PATH` (and indeed, that’s what the +initialisation script `/nix/etc/profile.d/nix.sh` does). This makes it +easier to switch to a different profile. You can do that using the +command `nix-env --switch-profile`: + +```console +$ nix-env --switch-profile /nix/var/nix/profiles/my-profile + +$ nix-env --switch-profile /nix/var/nix/profiles/default +``` + +These commands switch to the `my-profile` and default profile, +respectively. If the profile doesn’t exist, it will be created +automatically. You should be careful about storing a profile in another +location than the `profiles` directory, since otherwise it might not be +used as a root of the [garbage collector](garbage-collection.md). + +All `nix-env` operations work on the profile pointed to by +`~/.nix-profile`, but you can override this using the `--profile` option +(abbreviation `-p`): + +```console +$ nix-env -p /nix/var/nix/profiles/other-profile -i subversion +``` + +This will *not* change the `~/.nix-profile` symlink. diff --git a/doc/manual/src/package-management/s3-substituter.md b/doc/manual/src/package-management/s3-substituter.md new file mode 100644 index 000000000..a4f4d561f --- /dev/null +++ b/doc/manual/src/package-management/s3-substituter.md @@ -0,0 +1,145 @@ +# Serving a Nix store via S3 + +Nix has built-in support for storing and fetching store paths from +Amazon S3 and S3-compatible services. This uses the same *binary* +cache mechanism that Nix usually uses to fetch prebuilt binaries from +[cache.nixos.org](https://cache.nixos.org/). + +The following options can be specified as URL parameters to the S3 URL: + + - `profile` + The name of the AWS configuration profile to use. By default Nix + will use the `default` profile. + + - `region` + The region of the S3 bucket. `us–east-1` by default. + + If your bucket is not in `us–east-1`, you should always explicitly + specify the region parameter. + + - `endpoint` + The URL to your S3-compatible service, for when not using Amazon S3. + Do not specify this value if you're using Amazon S3. + + > **Note** + > + > This endpoint must support HTTPS and will use path-based + > addressing instead of virtual host based addressing. + + - `scheme` + The scheme used for S3 requests, `https` (default) or `http`. This + option allows you to disable HTTPS for binary caches which don't + support it. + + > **Note** + > + > HTTPS should be used if the cache might contain sensitive + > information. + +In this example we will use the bucket named `example-nix-cache`. + +## Anonymous Reads to your S3-compatible binary cache + +If your binary cache is publicly accessible and does not require +authentication, the simplest and easiest way to use Nix with your S3 +compatible binary cache is to use the HTTP URL for that cache. + +For AWS S3 the binary cache URL for example bucket will be exactly +<https://example-nix-cache.s3.amazonaws.com> or +<s3://example-nix-cache>. For S3 compatible binary caches, consult that +cache's documentation. + +Your bucket will need the following bucket policy: + +```json +{ + "Id": "DirectReads", + "Version": "2012-10-17", + "Statement": [ + { + "Sid": "AllowDirectReads", + "Action": [ + "s3:GetObject", + "s3:GetBucketLocation" + ], + "Effect": "Allow", + "Resource": [ + "arn:aws:s3:::example-nix-cache", + "arn:aws:s3:::example-nix-cache/*" + ], + "Principal": "*" + } + ] +} +``` + +## Authenticated Reads to your S3 binary cache + +For AWS S3 the binary cache URL for example bucket will be exactly +<s3://example-nix-cache>. + +Nix will use the [default credential provider +chain](https://docs.aws.amazon.com/sdk-for-cpp/v1/developer-guide/credentials.html) +for authenticating requests to Amazon S3. + +Nix supports authenticated reads from Amazon S3 and S3 compatible binary +caches. + +Your bucket will need a bucket policy allowing the desired users to +perform the `s3:GetObject` and `s3:GetBucketLocation` action on all +objects in the bucket. The [anonymous policy given +above](#anonymous-reads-to-your-s3-compatible-binary-cache) can be +updated to have a restricted `Principal` to support this. + +## Authenticated Writes to your S3-compatible binary cache + +Nix support fully supports writing to Amazon S3 and S3 compatible +buckets. The binary cache URL for our example bucket will be +<s3://example-nix-cache>. + +Nix will use the [default credential provider +chain](https://docs.aws.amazon.com/sdk-for-cpp/v1/developer-guide/credentials.html) +for authenticating requests to Amazon S3. + +Your account will need the following IAM policy to upload to the cache: + +```json +{ + "Version": "2012-10-17", + "Statement": [ + { + "Sid": "UploadToCache", + "Effect": "Allow", + "Action": [ + "s3:AbortMultipartUpload", + "s3:GetBucketLocation", + "s3:GetObject", + "s3:ListBucket", + "s3:ListBucketMultipartUploads", + "s3:ListMultipartUploadParts", + "s3:PutObject" + ], + "Resource": [ + "arn:aws:s3:::example-nix-cache", + "arn:aws:s3:::example-nix-cache/*" + ] + } + ] +} +``` + +## Examples + +To upload with a specific credential profile for Amazon S3: + +```console +$ nix copy nixpkgs.hello \ + --to 's3://example-nix-cache?profile=cache-upload®ion=eu-west-2' +``` + +To upload to an S3-compatible binary cache: + +```console +$ nix copy nixpkgs.hello --to \ + 's3://example-nix-cache?profile=cache-upload&scheme=https&endpoint=minio.example.com' +``` diff --git a/doc/manual/src/package-management/sharing-packages.md b/doc/manual/src/package-management/sharing-packages.md new file mode 100644 index 000000000..846ca6934 --- /dev/null +++ b/doc/manual/src/package-management/sharing-packages.md @@ -0,0 +1,6 @@ +# Sharing Packages Between Machines + +Sometimes you want to copy a package from one machine to another. Or, +you want to install some packages and you know that another machine +already has some or all of those packages or their dependencies. In that +case there are mechanisms to quickly copy packages between machines. diff --git a/doc/manual/src/package-management/ssh-substituter.md b/doc/manual/src/package-management/ssh-substituter.md new file mode 100644 index 000000000..6e5e258bc --- /dev/null +++ b/doc/manual/src/package-management/ssh-substituter.md @@ -0,0 +1,62 @@ +# Serving a Nix store via SSH + +You can tell Nix to automatically fetch needed binaries from a remote +Nix store via SSH. For example, the following installs Firefox, +automatically fetching any store paths in Firefox’s closure if they are +available on the server `avalon`: + +```console +$ nix-env -i firefox --substituters ssh://alice@avalon +``` + +This works similar to the binary cache substituter that Nix usually +uses, only using SSH instead of HTTP: if a store path `P` is needed, Nix +will first check if it’s available in the Nix store on `avalon`. If not, +it will fall back to using the binary cache substituter, and then to +building from source. + +> **Note** +> +> The SSH substituter currently does not allow you to enter an SSH +> passphrase interactively. Therefore, you should use `ssh-add` to load +> the decrypted private key into `ssh-agent`. + +You can also copy the closure of some store path, without installing it +into your profile, e.g. + +```console +$ nix-store -r /nix/store/m85bxg…-firefox-34.0.5 --substituters +ssh://alice@avalon +``` + +This is essentially equivalent to doing + +```console +$ nix-copy-closure --from alice@avalon +/nix/store/m85bxg…-firefox-34.0.5 +``` + +You can use SSH’s *forced command* feature to set up a restricted user +account for SSH substituter access, allowing read-only access to the +local Nix store, but nothing more. For example, add the following lines +to `sshd_config` to restrict the user `nix-ssh`: + + Match User nix-ssh + AllowAgentForwarding no + AllowTcpForwarding no + PermitTTY no + PermitTunnel no + X11Forwarding no + ForceCommand nix-store --serve + Match All + +On NixOS, you can accomplish the same by adding the following to your +`configuration.nix`: + +```nix +nix.sshServe.enable = true; +nix.sshServe.keys = [ "ssh-dss AAAAB3NzaC1k... bob@example.org" ]; +``` + +where the latter line lists the public keys of users that are allowed to +connect. diff --git a/doc/manual/src/quick-start.md b/doc/manual/src/quick-start.md new file mode 100644 index 000000000..71205923b --- /dev/null +++ b/doc/manual/src/quick-start.md @@ -0,0 +1,99 @@ +# Quick Start + +This chapter is for impatient people who don't like reading +documentation. For more in-depth information you are kindly referred +to subsequent chapters. + +1. Install single-user Nix by running the following: + + ```console + $ bash <(curl -L https://nixos.org/nix/install) + ``` + + This will install Nix in `/nix`. The install script will create + `/nix` using `sudo`, so make sure you have sufficient rights. (For + other installation methods, see + [here](installation/installation.md).) + +1. See what installable packages are currently available in the + channel: + + ```console + $ nix-env -qa + docbook-xml-4.3 + docbook-xml-4.5 + firefox-33.0.2 + hello-2.9 + libxslt-1.1.28 + … + ``` + +1. Install some packages from the channel: + + ```console + $ nix-env -i hello + ``` + + This should download pre-built packages; it should not build them + locally (if it does, something went wrong). + +1. Test that they work: + + ```console + $ which hello + /home/eelco/.nix-profile/bin/hello + $ hello + Hello, world! + ``` + +1. Uninstall a package: + + ```console + $ nix-env -e hello + ``` + +1. You can also test a package without installing it: + + ```console + $ nix-shell -p hello + ``` + + This builds or downloads GNU Hello and its dependencies, then drops + you into a Bash shell where the `hello` command is present, all + without affecting your normal environment: + + ```console + [nix-shell:~]$ hello + Hello, world! + + [nix-shell:~]$ exit + + $ hello + hello: command not found + ``` + +1. To keep up-to-date with the channel, do: + + ```console + $ nix-channel --update nixpkgs + $ nix-env -u '*' + ``` + + The latter command will upgrade each installed package for which + there is a “newer” version (as determined by comparing the version + numbers). + +1. If you're unhappy with the result of a `nix-env` action (e.g., an + upgraded package turned out not to work properly), you can go back: + + ```console + $ nix-env --rollback + ``` + +1. You should periodically run the Nix garbage collector to get rid of + unused packages, since uninstalls or upgrades don't actually delete + them: + + ```console + $ nix-collect-garbage -d + ``` diff --git a/doc/manual/src/release-notes/release-notes.md b/doc/manual/src/release-notes/release-notes.md new file mode 100644 index 000000000..b05d5ee0a --- /dev/null +++ b/doc/manual/src/release-notes/release-notes.md @@ -0,0 +1 @@ +# Nix Release Notes diff --git a/doc/manual/src/release-notes/rl-0.10.1.md b/doc/manual/src/release-notes/rl-0.10.1.md new file mode 100644 index 000000000..e1ed6558a --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.10.1.md @@ -0,0 +1,5 @@ +# Release 0.10.1 (2006-10-11) + +This release fixes two somewhat obscure bugs that occur when evaluating +Nix expressions that are stored inside the Nix store (`NIX-67`). These +do not affect most users. diff --git a/doc/manual/src/release-notes/rl-0.10.md b/doc/manual/src/release-notes/rl-0.10.md new file mode 100644 index 000000000..1301add26 --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.10.md @@ -0,0 +1,212 @@ +# Release 0.10 (2006-10-06) + +> **Note** +> +> This version of Nix uses Berkeley DB 4.4 instead of 4.3. The database +> is upgraded automatically, but you should be careful not to use old +> versions of Nix that still use Berkeley DB 4.3. In particular, if you +> use a Nix installed through Nix, you should run +> +> $ nix-store --clear-substitutes +> +> first. + +> **Warning** +> +> Also, the database schema has changed slighted to fix a performance +> issue (see below). When you run any Nix 0.10 command for the first +> time, the database will be upgraded automatically. This is +> irreversible. + + - `nix-env` usability improvements: + + - An option `--compare-versions` (or `-c`) has been added to + `nix-env + --query` to allow you to compare installed versions of packages + to available versions, or vice versa. An easy way to see if you + are up to date with what’s in your subscribed channels is + `nix-env -qc \*`. + + - `nix-env --query` now takes as arguments a list of package names + about which to show information, just like `--install`, etc.: + for example, `nix-env -q gcc`. Note that to show all + derivations, you need to specify `\*`. + + - `nix-env -i + pkgname` will now install the highest available version of + *pkgname*, rather than installing all available versions (which + would probably give collisions) (`NIX-31`). + + - `nix-env (-i|-u) --dry-run` now shows exactly which missing + paths will be built or substituted. + + - `nix-env -qa --description` shows human-readable descriptions of + packages, provided that they have a `meta.description` attribute + (which most packages in Nixpkgs don’t have yet). + + - New language features: + + - Reference scanning (which happens after each build) is much + faster and takes a constant amount of memory. + + - String interpolation. Expressions like + + "--with-freetype2-library=" + freetype + "/lib" + + can now be written as + + "--with-freetype2-library=${freetype}/lib" + + You can write arbitrary expressions within `${...}`, not just + identifiers. + + - Multi-line string literals. + + - String concatenations can now involve derivations, as in the + example `"--with-freetype2-library=" + + freetype + "/lib"`. This was not previously possible because + we need to register that a derivation that uses such a string is + dependent on `freetype`. The evaluator now properly propagates + this information. Consequently, the subpath operator (`~`) has + been deprecated. + + - Default values of function arguments can now refer to other + function arguments; that is, all arguments are in scope in the + default values (`NIX-45`). + + - Lots of new built-in primitives, such as functions for list + manipulation and integer arithmetic. See the manual for a + complete list. All primops are now available in the set + `builtins`, allowing one to test for the availability of primop + in a backwards-compatible way. + + - Real let-expressions: `let x = ...; + ... z = ...; in ...`. + + - New commands `nix-pack-closure` and `nix-unpack-closure` than can be + used to easily transfer a store path with all its dependencies to + another machine. Very convenient whenever you have some package on + your machine and you want to copy it somewhere else. + + - XML support: + + - `nix-env -q --xml` prints the installed or available packages in + an XML representation for easy processing by other tools. + + - `nix-instantiate --eval-only + --xml` prints an XML representation of the resulting term. (The + new flag `--strict` forces ‘deep’ evaluation of the result, + i.e., list elements and attributes are evaluated recursively.) + + - In Nix expressions, the primop `builtins.toXML` converts a term + to an XML representation. This is primarily useful for passing + structured information to builders. + + - You can now unambiguously specify which derivation to build or + install in `nix-env`, `nix-instantiate` and `nix-build` using the + `--attr` / `-A` flags, which takes an attribute name as argument. + (Unlike symbolic package names such as `subversion-1.4.0`, attribute + names in an attribute set are unique.) For instance, a quick way to + perform a test build of a package in Nixpkgs is `nix-build + pkgs/top-level/all-packages.nix -A + foo`. `nix-env -q + --attr` shows the attribute names corresponding to each derivation. + + - If the top-level Nix expression used by `nix-env`, `nix-instantiate` + or `nix-build` evaluates to a function whose arguments all have + default values, the function will be called automatically. Also, the + new command-line switch `--arg + name + value` can be used to specify function arguments on the command + line. + + - `nix-install-package --url + URL` allows a package to be installed directly from the given URL. + + - Nix now works behind an HTTP proxy server; just set the standard + environment variables `http_proxy`, `https_proxy`, `ftp_proxy` or + `all_proxy` appropriately. Functions such as `fetchurl` in Nixpkgs + also respect these variables. + + - `nix-build -o + symlink` allows the symlink to the build result to be named + something other than `result`. + + - Platform support: + + - Support for 64-bit platforms, provided a [suitably patched ATerm + library](http://bugzilla.sen.cwi.nl:8080/show_bug.cgi?id=606) is + used. Also, files larger than 2 GiB are now supported. + + - Added support for Cygwin (Windows, `i686-cygwin`), Mac OS X on + Intel (`i686-darwin`) and Linux on PowerPC (`powerpc-linux`). + + - Users of SMP and multicore machines will appreciate that the + number of builds to be performed in parallel can now be + specified in the configuration file in the `build-max-jobs` + setting. + + - Garbage collector improvements: + + - Open files (such as running programs) are now used as roots of + the garbage collector. This prevents programs that have been + uninstalled from being garbage collected while they are still + running. The script that detects these additional runtime roots + (`find-runtime-roots.pl`) is inherently system-specific, but it + should work on Linux and on all platforms that have the `lsof` + utility. + + - `nix-store --gc` (a.k.a. `nix-collect-garbage`) prints out the + number of bytes freed on standard output. `nix-store + --gc --print-dead` shows how many bytes would be freed by an + actual garbage collection. + + - `nix-collect-garbage -d` removes all old generations of *all* + profiles before calling the actual garbage collector (`nix-store + --gc`). This is an easy way to get rid of all old packages in + the Nix store. + + - `nix-store` now has an operation `--delete` to delete specific + paths from the Nix store. It won’t delete reachable + (non-garbage) paths unless `--ignore-liveness` is specified. + + - Berkeley DB 4.4’s process registry feature is used to recover from + crashed Nix processes. + + - A performance issue has been fixed with the `referer` table, which + stores the inverse of the `references` table (i.e., it tells you + what store paths refer to a given path). Maintaining this table + could take a quadratic amount of time, as well as a quadratic amount + of Berkeley DB log file space (in particular when running the + garbage collector) (`NIX-23`). + + - Nix now catches the `TERM` and `HUP` signals in addition to the + `INT` signal. So you can now do a `killall + nix-store` without triggering a database recovery. + + - `bsdiff` updated to version 4.3. + + - Substantial performance improvements in expression evaluation and + `nix-env -qa`, all thanks to [Valgrind](http://valgrind.org/). + Memory use has been reduced by a factor 8 or so. Big speedup by + memoisation of path hashing. + + - Lots of bug fixes, notably: + + - Make sure that the garbage collector can run successfully when + the disk is full (`NIX-18`). + + - `nix-env` now locks the profile to prevent races between + concurrent `nix-env` operations on the same profile (`NIX-7`). + + - Removed misleading messages from `nix-env -i` (e.g., + ``installing + `foo'`` followed by ``uninstalling + `foo'``) (`NIX-17`). + + - Nix source distributions are a lot smaller now since we no longer + include a full copy of the Berkeley DB source distribution (but only + the bits we need). + + - Header files are now installed so that external programs can use the + Nix libraries. diff --git a/doc/manual/src/release-notes/rl-0.11.md b/doc/manual/src/release-notes/rl-0.11.md new file mode 100644 index 000000000..d2f4d73aa --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.11.md @@ -0,0 +1,167 @@ +# Release 0.11 (2007-12-31) + +Nix 0.11 has many improvements over the previous stable release. The +most important improvement is secure multi-user support. It also +features many usability enhancements and language extensions, many of +them prompted by NixOS, the purely functional Linux distribution based +on Nix. Here is an (incomplete) list: + + - Secure multi-user support. A single Nix store can now be shared + between multiple (possible untrusted) users. This is an important + feature for NixOS, where it allows non-root users to install + software. The old setuid method for sharing a store between multiple + users has been removed. Details for setting up a multi-user store + can be found in the manual. + + - The new command `nix-copy-closure` gives you an easy and efficient + way to exchange software between machines. It copies the missing + parts of the closure of a set of store path to or from a remote + machine via `ssh`. + + - A new kind of string literal: strings between double single-quotes + (`''`) have indentation “intelligently” removed. This allows large + strings (such as shell scripts or configuration file fragments in + NixOS) to cleanly follow the indentation of the surrounding + expression. It also requires much less escaping, since `''` is less + common in most languages than `"`. + + - `nix-env` `--set` modifies the current generation of a profile so + that it contains exactly the specified derivation, and nothing else. + For example, `nix-env -p /nix/var/nix/profiles/browser --set + firefox` lets the profile named `browser` contain just Firefox. + + - `nix-env` now maintains meta-information about installed packages in + profiles. The meta-information is the contents of the `meta` + attribute of derivations, such as `description` or `homepage`. The + command `nix-env -q --xml + --meta` shows all meta-information. + + - `nix-env` now uses the `meta.priority` attribute of derivations to + resolve filename collisions between packages. Lower priority values + denote a higher priority. For instance, the GCC wrapper package and + the Binutils package in Nixpkgs both have a file `bin/ld`, so + previously if you tried to install both you would get a collision. + Now, on the other hand, the GCC wrapper declares a higher priority + than Binutils, so the former’s `bin/ld` is symlinked in the user + environment. + + - `nix-env -i / -u`: instead of breaking package ties by version, + break them by priority and version number. That is, if there are + multiple packages with the same name, then pick the package with the + highest priority, and only use the version if there are multiple + packages with the same priority. + + This makes it possible to mark specific versions/variant in Nixpkgs + more or less desirable than others. A typical example would be a + beta version of some package (e.g., `gcc-4.2.0rc1`) which should not + be installed even though it is the highest version, except when it + is explicitly selected (e.g., `nix-env -i + gcc-4.2.0rc1`). + + - `nix-env --set-flag` allows meta attributes of installed packages to + be modified. There are several attributes that can be usefully + modified, because they affect the behaviour of `nix-env` or the user + environment build script: + + - `meta.priority` can be changed to resolve filename clashes (see + above). + + - `meta.keep` can be set to `true` to prevent the package from + being upgraded or replaced. Useful if you want to hang on to an + older version of a package. + + - `meta.active` can be set to `false` to “disable” the package. + That is, no symlinks will be generated to the files of the + package, but it remains part of the profile (so it won’t be + garbage-collected). Set it back to `true` to re-enable the + package. + + - `nix-env -q` now has a flag `--prebuilt-only` (`-b`) that causes + `nix-env` to show only those derivations whose output is already in + the Nix store or that can be substituted (i.e., downloaded from + somewhere). In other words, it shows the packages that can be + installed “quickly”, i.e., don’t need to be built from source. The + `-b` flag is also available in `nix-env -i` and `nix-env -u` to + filter out derivations for which no pre-built binary is available. + + - The new option `--argstr` (in `nix-env`, `nix-instantiate` and + `nix-build`) is like `--arg`, except that the value is a string. For + example, `--argstr system + i686-linux` is equivalent to `--arg system + \"i686-linux\"` (note that `--argstr` prevents annoying quoting + around shell arguments). + + - `nix-store` has a new operation `--read-log` (`-l`) `paths` that + shows the build log of the given paths. + + - Nix now uses Berkeley DB 4.5. The database is upgraded + automatically, but you should be careful not to use old versions of + Nix that still use Berkeley DB 4.4. + + - The option `--max-silent-time` (corresponding to the configuration + setting `build-max-silent-time`) allows you to set a timeout on + builds — if a build produces no output on `stdout` or `stderr` for + the given number of seconds, it is terminated. This is useful for + recovering automatically from builds that are stuck in an infinite + loop. + + - `nix-channel`: each subscribed channel is its own attribute in the + top-level expression generated for the channel. This allows + disambiguation (e.g. `nix-env + -i -A nixpkgs_unstable.firefox`). + + - The substitutes table has been removed from the database. This makes + operations such as `nix-pull` and `nix-channel --update` much, much + faster. + + - `nix-pull` now supports bzip2-compressed manifests. This speeds up + channels. + + - `nix-prefetch-url` now has a limited form of caching. This is used + by `nix-channel` to prevent unnecessary downloads when the channel + hasn’t changed. + + - `nix-prefetch-url` now by default computes the SHA-256 hash of the + file instead of the MD5 hash. In calls to `fetchurl` you should pass + the `sha256` attribute instead of `md5`. You can pass either a + hexadecimal or a base-32 encoding of the hash. + + - Nix can now perform builds in an automatically generated “chroot”. + This prevents a builder from accessing stuff outside of the Nix + store, and thus helps ensure purity. This is an experimental + feature. + + - The new command `nix-store + --optimise` reduces Nix store disk space usage by finding identical + files in the store and hard-linking them to each other. It typically + reduces the size of the store by something like 25-35%. + + - `~/.nix-defexpr` can now be a directory, in which case the Nix + expressions in that directory are combined into an attribute set, + with the file names used as the names of the attributes. The command + `nix-env + --import` (which set the `~/.nix-defexpr` symlink) is removed. + + - Derivations can specify the new special attribute + `allowedReferences` to enforce that the references in the output of + a derivation are a subset of a declared set of paths. For example, + if `allowedReferences` is an empty list, then the output must not + have any references. This is used in NixOS to check that generated + files such as initial ramdisks for booting Linux don’t have any + dependencies. + + - The new attribute `exportReferencesGraph` allows builders access to + the references graph of their inputs. This is used in NixOS for + tasks such as generating ISO-9660 images that contain a Nix store + populated with the closure of certain paths. + + - Fixed-output derivations (like `fetchurl`) can define the attribute + `impureEnvVars` to allow external environment variables to be passed + to builders. This is used in Nixpkgs to support proxy configuration, + among other things. + + - Several new built-in functions: `builtins.attrNames`, + `builtins.filterSource`, `builtins.isAttrs`, `builtins.isFunction`, + `builtins.listToAttrs`, `builtins.stringLength`, `builtins.sub`, + `builtins.substring`, `throw`, `builtins.trace`, + `builtins.readFile`. diff --git a/doc/manual/src/release-notes/rl-0.12.md b/doc/manual/src/release-notes/rl-0.12.md new file mode 100644 index 000000000..3a4aba07d --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.12.md @@ -0,0 +1,123 @@ +# Release 0.12 (2008-11-20) + + - Nix no longer uses Berkeley DB to store Nix store metadata. The + principal advantages of the new storage scheme are: it works + properly over decent implementations of NFS (allowing Nix stores to + be shared between multiple machines); no recovery is needed when a + Nix process crashes; no write access is needed for read-only + operations; no more running out of Berkeley DB locks on certain + operations. + + You still need to compile Nix with Berkeley DB support if you want + Nix to automatically convert your old Nix store to the new schema. + If you don’t need this, you can build Nix with the `configure` + option `--disable-old-db-compat`. + + After the automatic conversion to the new schema, you can delete the + old Berkeley DB files: + + $ cd /nix/var/nix/db + $ rm __db* log.* derivers references referrers reserved validpaths DB_CONFIG + + The new metadata is stored in the directories `/nix/var/nix/db/info` + and `/nix/var/nix/db/referrer`. Though the metadata is stored in + human-readable plain-text files, they are not intended to be + human-editable, as Nix is rather strict about the format. + + The new storage schema may or may not require less disk space than + the Berkeley DB environment, mostly depending on the cluster size of + your file system. With 1 KiB clusters (which seems to be the `ext3` + default nowadays) it usually takes up much less space. + + - There is a new substituter that copies paths directly from other + (remote) Nix stores mounted somewhere in the filesystem. For + instance, you can speed up an installation by mounting some remote + Nix store that already has the packages in question via NFS or + `sshfs`. The environment variable `NIX_OTHER_STORES` specifies the + locations of the remote Nix directories, e.g. `/mnt/remote-fs/nix`. + + - New `nix-store` operations `--dump-db` and `--load-db` to dump and + reload the Nix database. + + - The garbage collector has a number of new options to allow only some + of the garbage to be deleted. The option `--max-freed N` tells the + collector to stop after at least *N* bytes have been deleted. The + option `--max-links + N` tells it to stop after the link count on `/nix/store` has dropped + below *N*. This is useful for very large Nix stores on filesystems + with a 32000 subdirectories limit (like `ext3`). The option + `--use-atime` causes store paths to be deleted in order of ascending + last access time. This allows non-recently used stuff to be deleted. + The option `--max-atime time` specifies an upper limit to the last + accessed time of paths that may be deleted. For instance, + + ``` + $ nix-store --gc -v --max-atime $(date +%s -d "2 months ago") + ``` + + deletes everything that hasn’t been accessed in two months. + + - `nix-env` now uses optimistic profile locking when performing an + operation like installing or upgrading, instead of setting an + exclusive lock on the profile. This allows multiple `nix-env -i / -u + / -e` operations on the same profile in parallel. If a `nix-env` + operation sees at the end that the profile was changed in the + meantime by another process, it will just restart. This is generally + cheap because the build results are still in the Nix store. + + - The option `--dry-run` is now supported by `nix-store -r` and + `nix-build`. + + - The information previously shown by `--dry-run` (i.e., which + derivations will be built and which paths will be substituted) is + now always shown by `nix-env`, `nix-store -r` and `nix-build`. The + total download size of substitutable paths is now also shown. For + instance, a build will show something like + + the following derivations will be built: + /nix/store/129sbxnk5n466zg6r1qmq1xjv9zymyy7-activate-configuration.sh.drv + /nix/store/7mzy971rdm8l566ch8hgxaf89x7lr7ik-upstart-jobs.drv + ... + the following paths will be downloaded/copied (30.02 MiB): + /nix/store/4m8pvgy2dcjgppf5b4cj5l6wyshjhalj-samba-3.2.4 + /nix/store/7h1kwcj29ip8vk26rhmx6bfjraxp0g4l-libunwind-0.98.6 + ... + + - Language features: + + - @-patterns as in Haskell. For instance, in a function definition + + f = args @ {x, y, z}: ...; + + `args` refers to the argument as a whole, which is further + pattern-matched against the attribute set pattern `{x, y, z}`. + + - “`...`” (ellipsis) patterns. An attribute set pattern can now + say `...` at the end of the attribute name list to specify that + the function takes *at least* the listed attributes, while + ignoring additional attributes. For instance, + + {stdenv, fetchurl, fuse, ...}: ... + + defines a function that accepts any attribute set that includes + at least the three listed attributes. + + - New primops: `builtins.parseDrvName` (split a package name + string like `"nix-0.12pre12876"` into its name and version + components, e.g. `"nix"` and `"0.12pre12876"`), + `builtins.compareVersions` (compare two version strings using + the same algorithm that `nix-env` uses), `builtins.length` + (efficiently compute the length of a list), `builtins.mul` + (integer multiplication), `builtins.div` (integer division). + + - `nix-prefetch-url` now supports `mirror://` URLs, provided that the + environment variable `NIXPKGS_ALL` points at a Nixpkgs tree. + + - Removed the commands `nix-pack-closure` and `nix-unpack-closure`. + You can do almost the same thing but much more efficiently by doing + `nix-store --export + $(nix-store -qR paths) > closure` and `nix-store --import < + closure`. + + - Lots of bug fixes, including a big performance bug in the handling + of `with`-expressions. diff --git a/doc/manual/src/release-notes/rl-0.13.md b/doc/manual/src/release-notes/rl-0.13.md new file mode 100644 index 000000000..13a60e01c --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.13.md @@ -0,0 +1,55 @@ +# Release 0.13 (2009-11-05) + +This is primarily a bug fix release. It has some new features: + + - Syntactic sugar for writing nested attribute sets. Instead of + + { + foo = { + bar = 123; + xyzzy = true; + }; + a = { b = { c = "d"; }; }; + } + + you can write + + { + foo.bar = 123; + foo.xyzzy = true; + a.b.c = "d"; + } + + This is useful, for instance, in NixOS configuration files. + + - Support for Nix channels generated by Hydra, the Nix-based + continuous build system. (Hydra generates NAR archives on the fly, + so the size and hash of these archives isn’t known in advance.) + + - Support `i686-linux` builds directly on `x86_64-linux` Nix + installations. This is implemented using the `personality()` + syscall, which causes `uname` to return `i686` in child processes. + + - Various improvements to the `chroot` support. Building in a `chroot` + works quite well now. + + - Nix no longer blocks if it tries to build a path and another process + is already building the same path. Instead it tries to build another + buildable path first. This improves parallelism. + + - Support for large (\> 4 GiB) files in NAR archives. + + - Various (performance) improvements to the remote build mechanism. + + - New primops: `builtins.addErrorContext` (to add a string to stack + traces — useful for debugging), `builtins.isBool`, + `builtins.isString`, `builtins.isInt`, `builtins.intersectAttrs`. + + - OpenSolaris support (Sander van der Burg). + + - Stack traces are no longer displayed unless the `--show-trace` + option is used. + + - The scoping rules for `inherit + (e) ...` in recursive attribute sets have changed. The expression + *e* can now refer to the attributes defined in the containing set. diff --git a/doc/manual/src/release-notes/rl-0.14.md b/doc/manual/src/release-notes/rl-0.14.md new file mode 100644 index 000000000..9d58f2072 --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.14.md @@ -0,0 +1,21 @@ +# Release 0.14 (2010-02-04) + +This release has the following improvements: + + - The garbage collector now starts deleting garbage much faster than + before. It no longer determines liveness of all paths in the store, + but does so on demand. + + - Added a new operation, `nix-store --query + --roots`, that shows the garbage collector roots that directly or + indirectly point to the given store paths. + + - Removed support for converting Berkeley DB-based Nix databases to + the new schema. + + - Removed the `--use-atime` and `--max-atime` garbage collector + options. They were not very useful in practice. + + - On Windows, Nix now requires Cygwin 1.7.x. + + - A few bug fixes. diff --git a/doc/manual/src/release-notes/rl-0.15.md b/doc/manual/src/release-notes/rl-0.15.md new file mode 100644 index 000000000..48e2a6f1b --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.15.md @@ -0,0 +1,5 @@ +# Release 0.15 (2010-03-17) + +This is a bug-fix release. Among other things, it fixes building on Mac +OS X (Snow Leopard), and improves the contents of `/etc/passwd` and +`/etc/group` in `chroot` builds. diff --git a/doc/manual/src/release-notes/rl-0.16.md b/doc/manual/src/release-notes/rl-0.16.md new file mode 100644 index 000000000..23ac53786 --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.16.md @@ -0,0 +1,25 @@ +# Release 0.16 (2010-08-17) + +This release has the following improvements: + + - The Nix expression evaluator is now much faster in most cases: + typically, [3 to 8 times compared to the old + implementation](http://www.mail-archive.com/nix-dev@cs.uu.nl/msg04113.html). + It also uses less memory. It no longer depends on the ATerm library. + + - Support for configurable parallelism inside builders. Build scripts + have always had the ability to perform multiple build actions in + parallel (for instance, by running `make -j + 2`), but this was not desirable because the number of actions to be + performed in parallel was not configurable. Nix now has an option + `--cores + N` as well as a configuration setting `build-cores = + N` that causes the environment variable `NIX_BUILD_CORES` to be set + to *N* when the builder is invoked. The builder can use this at its + discretion to perform a parallel build, e.g., by calling `make -j + N`. In Nixpkgs, this can be enabled on a per-package basis by + setting the derivation attribute `enableParallelBuilding` to `true`. + + - `nix-store -q` now supports XML output through the `--xml` flag. + + - Several bug fixes. diff --git a/doc/manual/src/release-notes/rl-0.5.md b/doc/manual/src/release-notes/rl-0.5.md new file mode 100644 index 000000000..5cff2da0b --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.5.md @@ -0,0 +1,3 @@ +# Release 0.5 and earlier + +Please refer to the Subversion commit log messages. diff --git a/doc/manual/src/release-notes/rl-0.6.md b/doc/manual/src/release-notes/rl-0.6.md new file mode 100644 index 000000000..ed2d21583 --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.6.md @@ -0,0 +1,64 @@ +# Release 0.6 (2004-11-14) + + - Rewrite of the normalisation engine. + + - Multiple builds can now be performed in parallel (option `-j`). + + - Distributed builds. Nix can now call a shell script to forward + builds to Nix installations on remote machines, which may or may + not be of the same platform type. + + - Option `--fallback` allows recovery from broken substitutes. + + - Option `--keep-going` causes building of other (unaffected) + derivations to continue if one failed. + + - Improvements to the garbage collector (i.e., it should actually work + now). + + - Setuid Nix installations allow a Nix store to be shared among + multiple users. + + - Substitute registration is much faster now. + + - A utility `nix-build` to build a Nix expression and create a symlink + to the result int the current directory; useful for testing Nix + derivations. + + - Manual updates. + + - `nix-env` changes: + + - Derivations for other platforms are filtered out (which can be + overridden using `--system-filter`). + + - `--install` by default now uninstall previous derivations with + the same name. + + - `--upgrade` allows upgrading to a specific version. + + - New operation `--delete-generations` to remove profile + generations (necessary for effective garbage collection). + + - Nicer output (sorted, columnised). + + - More sensible verbosity levels all around (builder output is now + shown always, unless `-Q` is given). + + - Nix expression language changes: + + - New language construct: `with + E1; + E2` brings all attributes defined in the attribute set *E1* in + scope in *E2*. + + - Added a `map` function. + + - Various new operators (e.g., string concatenation). + + - Expression evaluation is much faster. + + - An Emacs mode for editing Nix expressions (with syntax highlighting + and indentation) has been added. + + - Many bug fixes. diff --git a/doc/manual/src/release-notes/rl-0.7.md b/doc/manual/src/release-notes/rl-0.7.md new file mode 100644 index 000000000..d873fe890 --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.7.md @@ -0,0 +1,21 @@ +# Release 0.7 (2005-01-12) + + - Binary patching. When upgrading components using pre-built binaries + (through nix-pull / nix-channel), Nix can automatically download and + apply binary patches to already installed components instead of full + downloads. Patching is “smart”: if there is a *sequence* of patches + to an installed component, Nix will use it. Patches are currently + generated automatically between Nixpkgs (pre-)releases. + + - Simplifications to the substitute mechanism. + + - Nix-pull now stores downloaded manifests in + `/nix/var/nix/manifests`. + + - Metadata on files in the Nix store is canonicalised after builds: + the last-modified timestamp is set to 0 (00:00:00 1/1/1970), the + mode is set to 0444 or 0555 (readable and possibly executable by + all; setuid/setgid bits are dropped), and the group is set to the + default. This ensures that the result of a build and an installation + through a substitute is the same; and that timestamp dependencies + are revealed. diff --git a/doc/manual/src/release-notes/rl-0.8.1.md b/doc/manual/src/release-notes/rl-0.8.1.md new file mode 100644 index 000000000..7629f81cb --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.8.1.md @@ -0,0 +1,8 @@ +# Release 0.8.1 (2005-04-13) + +This is a bug fix release. + + - Patch downloading was broken. + + - The garbage collector would not delete paths that had references + from invalid (but substitutable) paths. diff --git a/doc/manual/src/release-notes/rl-0.8.md b/doc/manual/src/release-notes/rl-0.8.md new file mode 100644 index 000000000..626c0c92b --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.8.md @@ -0,0 +1,166 @@ +# Release 0.8 (2005-04-11) + +NOTE: the hashing scheme in Nix 0.8 changed (as detailed below). As a +result, `nix-pull` manifests and channels built for Nix 0.7 and below +will not work anymore. However, the Nix expression language has not +changed, so you can still build from source. Also, existing user +environments continue to work. Nix 0.8 will automatically upgrade the +database schema of previous installations when it is first run. + +If you get the error message + + you have an old-style manifest `/nix/var/nix/manifests/[...]'; please + delete it + +you should delete previously downloaded manifests: + + $ rm /nix/var/nix/manifests/* + +If `nix-channel` gives the error message + + manifest `http://catamaran.labs.cs.uu.nl/dist/nix/channels/[channel]/MANIFEST' + is too old (i.e., for Nix <= 0.7) + +then you should unsubscribe from the offending channel (`nix-channel +--remove +URL`; leave out `/MANIFEST`), and subscribe to the same URL, with +`channels` replaced by `channels-v3` (e.g., +<http://catamaran.labs.cs.uu.nl/dist/nix/channels-v3/nixpkgs-unstable>). + +Nix 0.8 has the following improvements: + + - The cryptographic hashes used in store paths are now 160 bits long, + but encoded in base-32 so that they are still only 32 characters + long (e.g., + `/nix/store/csw87wag8bqlqk7ipllbwypb14xainap-atk-1.9.0`). (This is + actually a 160 bit truncation of a SHA-256 hash.) + + - Big cleanups and simplifications of the basic store semantics. The + notion of “closure store expressions” is gone (and so is the notion + of “successors”); the file system references of a store path are now + just stored in the database. + + For instance, given any store path, you can query its closure: + + $ nix-store -qR $(which firefox) + ... lots of paths ... + + Also, Nix now remembers for each store path the derivation that + built it (the “deriver”): + + $ nix-store -qR $(which firefox) + /nix/store/4b0jx7vq80l9aqcnkszxhymsf1ffa5jd-firefox-1.0.1.drv + + So to see the build-time dependencies, you can do + + $ nix-store -qR $(nix-store -qd $(which firefox)) + + or, in a nicer format: + + $ nix-store -q --tree $(nix-store -qd $(which firefox)) + + File system references are also stored in reverse. For instance, you + can query all paths that directly or indirectly use a certain Glibc: + + $ nix-store -q --referrers-closure \ + /nix/store/8lz9yc6zgmc0vlqmn2ipcpkjlmbi51vv-glibc-2.3.4 + + - The concept of fixed-output derivations has been formalised. + Previously, functions such as `fetchurl` in Nixpkgs used a hack + (namely, explicitly specifying a store path hash) to prevent changes + to, say, the URL of the file from propagating upwards through the + dependency graph, causing rebuilds of everything. This can now be + done cleanly by specifying the `outputHash` and `outputHashAlgo` + attributes. Nix itself checks that the content of the output has the + specified hash. (This is important for maintaining certain + invariants necessary for future work on secure shared stores.) + + - One-click installation :-) It is now possible to install any + top-level component in Nixpkgs directly, through the web — see, + e.g., <http://catamaran.labs.cs.uu.nl/dist/nixpkgs-0.8/>. All you + have to do is associate `/nix/bin/nix-install-package` with the MIME + type `application/nix-package` (or the extension `.nixpkg`), and + clicking on a package link will cause it to be installed, with all + appropriate dependencies. If you just want to install some specific + application, this is easier than subscribing to a channel. + + - `nix-store -r + PATHS` now builds all the derivations PATHS in parallel. Previously + it did them sequentially (though exploiting possible parallelism + between subderivations). This is nice for build farms. + + - `nix-channel` has new operations `--list` and `--remove`. + + - New ways of installing components into user environments: + + - Copy from another user environment: + + $ nix-env -i --from-profile .../other-profile firefox + + - Install a store derivation directly (bypassing the Nix + expression language entirely): + + $ nix-env -i /nix/store/z58v41v21xd3...-aterm-2.3.1.drv + + (This is used to implement `nix-install-package`, which is + therefore immune to evolution in the Nix expression language.) + + - Install an already built store path directly: + + $ nix-env -i /nix/store/hsyj5pbn0d9i...-aterm-2.3.1 + + - Install the result of a Nix expression specified as a + command-line argument: + + $ nix-env -f .../i686-linux.nix -i -E 'x: x.firefoxWrapper' + + The difference with the normal installation mode is that `-E` + does not use the `name` attributes of derivations. Therefore, + this can be used to disambiguate multiple derivations with the + same name. + + - A hash of the contents of a store path is now stored in the database + after a successful build. This allows you to check whether store + paths have been tampered with: `nix-store + --verify --check-contents`. + + - Implemented a concurrent garbage collector. It is now always safe to + run the garbage collector, even if other Nix operations are + happening simultaneously. + + However, there can still be GC races if you use `nix-instantiate` + and `nix-store + --realise` directly to build things. To prevent races, use the + `--add-root` flag of those commands. + + - The garbage collector now finally deletes paths in the right order + (i.e., topologically sorted under the “references” relation), thus + making it safe to interrupt the collector without risking a store + that violates the closure invariant. + + - Likewise, the substitute mechanism now downloads files in the right + order, thus preserving the closure invariant at all times. + + - The result of `nix-build` is now registered as a root of the garbage + collector. If the `./result` link is deleted, the GC root disappears + automatically. + + - The behaviour of the garbage collector can be changed globally by + setting options in `/nix/etc/nix/nix.conf`. + + - `gc-keep-derivations` specifies whether deriver links should be + followed when searching for live paths. + + - `gc-keep-outputs` specifies whether outputs of derivations + should be followed when searching for live paths. + + - `env-keep-derivations` specifies whether user environments + should store the paths of derivations when they are added (thus + keeping the derivations alive). + + - New `nix-env` query flags `--drv-path` and `--out-path`. + + - `fetchurl` allows SHA-1 and SHA-256 in addition to MD5. Just specify + the attribute `sha1` or `sha256` instead of `md5`. + + - Manual updates. diff --git a/doc/manual/src/release-notes/rl-0.9.1.md b/doc/manual/src/release-notes/rl-0.9.1.md new file mode 100644 index 000000000..9c20eed1b --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.9.1.md @@ -0,0 +1,4 @@ +# Release 0.9.1 (2005-09-20) + +This bug fix release addresses a problem with the ATerm library when the +`--with-aterm` flag in `configure` was *not* used. diff --git a/doc/manual/src/release-notes/rl-0.9.2.md b/doc/manual/src/release-notes/rl-0.9.2.md new file mode 100644 index 000000000..0caaf28de --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.9.2.md @@ -0,0 +1,11 @@ +# Release 0.9.2 (2005-09-21) + +This bug fix release fixes two problems on Mac OS X: + + - If Nix was linked against statically linked versions of the ATerm or + Berkeley DB library, there would be dynamic link errors at runtime. + + - `nix-pull` and `nix-push` intermittently failed due to race + conditions involving pipes and child processes with error messages + such as `open2: open(GLOB(0x180b2e4), >&=9) failed: Bad + file descriptor at /nix/bin/nix-pull line 77` (issue `NIX-14`). diff --git a/doc/manual/src/release-notes/rl-0.9.md b/doc/manual/src/release-notes/rl-0.9.md new file mode 100644 index 000000000..8c3e1b28e --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.9.md @@ -0,0 +1,72 @@ +# Release 0.9 (2005-09-16) + +NOTE: this version of Nix uses Berkeley DB 4.3 instead of 4.2. The +database is upgraded automatically, but you should be careful not to use +old versions of Nix that still use Berkeley DB 4.2. In particular, if +you use a Nix installed through Nix, you should run + + $ nix-store --clear-substitutes + +first. + + - Unpacking of patch sequences is much faster now since we no longer + do redundant unpacking and repacking of intermediate paths. + + - Nix now uses Berkeley DB 4.3. + + - The `derivation` primitive is lazier. Attributes of dependent + derivations can mutually refer to each other (as long as there are + no data dependencies on the `outPath` and `drvPath` attributes + computed by `derivation`). + + For example, the expression `derivation + attrs` now evaluates to (essentially) + + attrs // { + type = "derivation"; + outPath = derivation! attrs; + drvPath = derivation! attrs; + } + + where `derivation!` is a primop that does the actual derivation + instantiation (i.e., it does what `derivation` used to do). The + advantage is that it allows commands such as `nix-env -qa` and + `nix-env -i` to be much faster since they no longer need to + instantiate all derivations, just the `name` attribute. + + Also, it allows derivations to cyclically reference each other, for + example, + + webServer = derivation { + ... + hostName = "svn.cs.uu.nl"; + services = [svnService]; + }; + + svnService = derivation { + ... + hostName = webServer.hostName; + }; + + Previously, this would yield a black hole (infinite recursion). + + - `nix-build` now defaults to using `./default.nix` if no Nix + expression is specified. + + - `nix-instantiate`, when applied to a Nix expression that evaluates + to a function, will call the function automatically if all its + arguments have defaults. + + - Nix now uses libtool to build dynamic libraries. This reduces the + size of executables. + + - A new list concatenation operator `++`. For example, `[1 2 3] ++ + [4 5 + 6]` evaluates to `[1 2 3 4 5 + 6]`. + + - Some currently undocumented primops to support low-level build + management using Nix (i.e., using Nix as a Make replacement). See + the commit messages for `r3578` and `r3580`. + + - Various bug fixes and performance improvements. diff --git a/doc/manual/src/release-notes/rl-1.0.md b/doc/manual/src/release-notes/rl-1.0.md new file mode 100644 index 000000000..cdb257787 --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.0.md @@ -0,0 +1,68 @@ +# Release 1.0 (2012-05-11) + +There have been numerous improvements and bug fixes since the previous +release. Here are the most significant: + + - Nix can now optionally use the Boehm garbage collector. This + significantly reduces the Nix evaluator’s memory footprint, + especially when evaluating large NixOS system configurations. It can + be enabled using the `--enable-gc` configure option. + + - Nix now uses SQLite for its database. This is faster and more + flexible than the old *ad hoc* format. SQLite is also used to cache + the manifests in `/nix/var/nix/manifests`, resulting in a + significant speedup. + + - Nix now has an search path for expressions. The search path is set + using the environment variable `NIX_PATH` and the `-I` command line + option. In Nix expressions, paths between angle brackets are used to + specify files that must be looked up in the search path. For + instance, the expression `<nixpkgs/default.nix>` looks for a file + `nixpkgs/default.nix` relative to every element in the search path. + + - The new command `nix-build --run-env` builds all dependencies of a + derivation, then starts a shell in an environment containing all + variables from the derivation. This is useful for reproducing the + environment of a derivation for development. + + - The new command `nix-store --verify-path` verifies that the contents + of a store path have not changed. + + - The new command `nix-store --print-env` prints out the environment + of a derivation in a format that can be evaluated by a shell. + + - Attribute names can now be arbitrary strings. For instance, you can + write `{ "foo-1.2" = …; "bla bla" = …; }."bla + bla"`. + + - Attribute selection can now provide a default value using the `or` + operator. For instance, the expression `x.y.z or e` evaluates to the + attribute `x.y.z` if it exists, and `e` otherwise. + + - The right-hand side of the `?` operator can now be an attribute + path, e.g., `attrs ? + a.b.c`. + + - On Linux, Nix will now make files in the Nix store immutable on + filesystems that support it. This prevents accidental modification + of files in the store by the root user. + + - Nix has preliminary support for derivations with multiple outputs. + This is useful because it allows parts of a package to be deployed + and garbage-collected separately. For instance, development parts of + a package such as header files or static libraries would typically + not be part of the closure of an application, resulting in reduced + disk usage and installation time. + + - The Nix store garbage collector is faster and holds the global lock + for a shorter amount of time. + + - The option `--timeout` (corresponding to the configuration setting + `build-timeout`) allows you to set an absolute timeout on builds — + if a build runs for more than the given number of seconds, it is + terminated. This is useful for recovering automatically from builds + that are stuck in an infinite loop but keep producing output, and + for which `--max-silent-time` is ineffective. + + - Nix development has moved to GitHub + (<https://github.com/NixOS/nix>). diff --git a/doc/manual/src/release-notes/rl-1.1.md b/doc/manual/src/release-notes/rl-1.1.md new file mode 100644 index 000000000..1e658fe15 --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.1.md @@ -0,0 +1,61 @@ +# Release 1.1 (2012-07-18) + +This release has the following improvements: + + - On Linux, when doing a chroot build, Nix now uses various namespace + features provided by the Linux kernel to improve build isolation. + Namely: + + - The private network namespace ensures that builders cannot talk + to the outside world (or vice versa): each build only sees a + private loopback interface. This also means that two concurrent + builds can listen on the same port (e.g. as part of a test) + without conflicting with each other. + + - The PID namespace causes each build to start as PID 1. Processes + outside of the chroot are not visible to those on the inside. On + the other hand, processes inside the chroot *are* visible from + the outside (though with different PIDs). + + - The IPC namespace prevents the builder from communicating with + outside processes using SysV IPC mechanisms (shared memory, + message queues, semaphores). It also ensures that all IPC + objects are destroyed when the builder exits. + + - The UTS namespace ensures that builders see a hostname of + `localhost` rather than the actual hostname. + + - The private mount namespace was already used by Nix to ensure + that the bind-mounts used to set up the chroot are cleaned up + automatically. + + - Build logs are now compressed using `bzip2`. The command `nix-store + -l` decompresses them on the fly. This can be disabled by setting + the option `build-compress-log` to `false`. + + - The creation of build logs in `/nix/var/log/nix/drvs` can be + disabled by setting the new option `build-keep-log` to `false`. This + is useful, for instance, for Hydra build machines. + + - Nix now reserves some space in `/nix/var/nix/db/reserved` to ensure + that the garbage collector can run successfully if the disk is full. + This is necessary because SQLite transactions fail if the disk is + full. + + - Added a basic `fetchurl` function. This is not intended to replace + the `fetchurl` in Nixpkgs, but is useful for bootstrapping; e.g., it + will allow us to get rid of the bootstrap binaries in the Nixpkgs + source tree and download them instead. You can use it by doing + `import <nix/fetchurl.nix> { url = + url; sha256 = + "hash"; }`. (Shea Levy) + + - Improved RPM spec file. (Michel Alexandre Salim) + + - Support for on-demand socket-based activation in the Nix daemon with + `systemd`. + + - Added a manpage for nix.conf5. + + - When using the Nix daemon, the `-s` flag in `nix-env -qa` is now + much faster. diff --git a/doc/manual/src/release-notes/rl-1.10.md b/doc/manual/src/release-notes/rl-1.10.md new file mode 100644 index 000000000..2bb859536 --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.10.md @@ -0,0 +1,31 @@ +# Release 1.10 (2015-09-03) + +This is primarily a bug fix release. It also has a number of new +features: + + - A number of builtin functions have been added to reduce + Nixpkgs/NixOS evaluation time and memory consumption: `all`, `any`, + `concatStringsSep`, `foldl’`, `genList`, `replaceStrings`, `sort`. + + - The garbage collector is more robust when the disk is full. + + - Nix supports a new API for building derivations that doesn’t require + a `.drv` file to be present on disk; it only requires an in-memory + representation of the derivation. This is used by the Hydra + continuous build system to make remote builds more efficient. + + - The function `<nix/fetchurl.nix>` now uses a *builtin* builder (i.e. + it doesn’t require starting an external process; the download is + performed by Nix itself). This ensures that derivation paths don’t + change when Nix is upgraded, and obviates the need for ugly hacks to + support chroot execution. + + - `--version -v` now prints some configuration information, in + particular what compile-time optional features are enabled, and the + paths of various directories. + + - Build users have their supplementary groups set correctly. + +This release has contributions from Eelco Dolstra, Guillaume Maudoux, +Iwan Aucamp, Jaka Hudoklin, Kirill Elagin, Ludovic Courtès, Manolis +Ragkousis, Nicolas B. Pierron and Shea Levy. diff --git a/doc/manual/src/release-notes/rl-1.11.10.md b/doc/manual/src/release-notes/rl-1.11.10.md new file mode 100644 index 000000000..d1efe1d0b --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.11.10.md @@ -0,0 +1,21 @@ +# Release 1.11.10 (2017-06-12) + +This release fixes a security bug in Nix’s “build user” build isolation +mechanism. Previously, Nix builders had the ability to create setuid +binaries owned by a `nixbld` user. Such a binary could then be used by +an attacker to assume a `nixbld` identity and interfere with subsequent +builds running under the same UID. + +To prevent this issue, Nix now disallows builders to create setuid and +setgid binaries. On Linux, this is done using a seccomp BPF filter. Note +that this imposes a small performance penalty (e.g. 1% when building GNU +Hello). Using seccomp, we now also prevent the creation of extended +attributes and POSIX ACLs since these cannot be represented in the NAR +format and (in the case of POSIX ACLs) allow bypassing regular Nix store +permissions. On macOS, the restriction is implemented using the existing +sandbox mechanism, which now uses a minimal “allow all except the +creation of setuid/setgid binaries” profile when regular sandboxing is +disabled. On other platforms, the “build user” mechanism is now +disabled. + +Thanks go to Linus Heckemann for discovering and reporting this bug. diff --git a/doc/manual/src/release-notes/rl-1.11.md b/doc/manual/src/release-notes/rl-1.11.md new file mode 100644 index 000000000..fbabdaa2f --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.11.md @@ -0,0 +1,87 @@ +# Release 1.11 (2016-01-19) + +This is primarily a bug fix release. It also has a number of new +features: + + - `nix-prefetch-url` can now download URLs specified in a Nix + expression. For example, + + $ nix-prefetch-url -A hello.src + + will prefetch the file specified by the `fetchurl` call in the + attribute `hello.src` from the Nix expression in the current + directory, and print the cryptographic hash of the resulting file on + stdout. This differs from `nix-build -A + hello.src` in that it doesn't verify the hash, and is thus useful + when you’re updating a Nix expression. + + You can also prefetch the result of functions that unpack a tarball, + such as `fetchFromGitHub`. For example: + + $ nix-prefetch-url --unpack https://github.com/NixOS/patchelf/archive/0.8.tar.gz + + or from a Nix expression: + + $ nix-prefetch-url -A nix-repl.src + + - The builtin function `<nix/fetchurl.nix>` now supports downloading + and unpacking NARs. This removes the need to have multiple downloads + in the Nixpkgs stdenv bootstrap process (like a separate busybox + binary for Linux, or curl/mkdir/sh/bzip2 for Darwin). Now all those + files can be combined into a single NAR, optionally compressed using + `xz`. + + - Nix now supports SHA-512 hashes for verifying fixed-output + derivations, and in `builtins.hashString`. + + - The new flag `--option build-repeat + N` will cause every build to be executed *N*+1 times. If the build + output differs between any round, the build is rejected, and the + output paths are not registered as valid. This is primarily useful + to verify build determinism. (We already had a `--check` option to + repeat a previously succeeded build. However, with `--check`, + non-deterministic builds are registered in the DB. Preventing that + is useful for Hydra to ensure that non-deterministic builds don't + end up getting published to the binary cache.) + + - The options `--check` and `--option + build-repeat N`, if they detect a difference between two runs of the + same derivation and `-K` is given, will make the output of the other + run available under `store-path-check`. This makes it easier to + investigate the non-determinism using tools like `diffoscope`, e.g., + + $ nix-build pkgs/stdenv/linux -A stage1.pkgs.zlib --check -K + error: derivation ‘/nix/store/l54i8wlw2265…-zlib-1.2.8.drv’ may not + be deterministic: output ‘/nix/store/11a27shh6n2i…-zlib-1.2.8’ + differs from ‘/nix/store/11a27shh6n2i…-zlib-1.2.8-check’ + + $ diffoscope /nix/store/11a27shh6n2i…-zlib-1.2.8 /nix/store/11a27shh6n2i…-zlib-1.2.8-check + … + ├── lib/libz.a + │ ├── metadata + │ │ @@ -1,15 +1,15 @@ + │ │ -rw-r--r-- 30001/30000 3096 Jan 12 15:20 2016 adler32.o + … + │ │ +rw-r--r-- 30001/30000 3096 Jan 12 15:28 2016 adler32.o + … + + - Improved FreeBSD support. + + - `nix-env -qa --xml --meta` now prints license information. + + - The maximum number of parallel TCP connections that the binary cache + substituter will use has been decreased from 150 to 25. This should + prevent upsetting some broken NAT routers, and also improves + performance. + + - All "chroot"-containing strings got renamed to "sandbox". In + particular, some Nix options got renamed, but the old names are + still accepted as lower-priority aliases. + +This release has contributions from Anders Claesson, Anthony Cowley, +Bjørn Forsman, Brian McKenna, Danny Wilson, davidak, Eelco Dolstra, +Fabian Schmitthenner, FrankHB, Ilya Novoselov, janus, Jim Garrison, John +Ericson, Jude Taylor, Ludovic Courtès, Manuel Jacob, Mathnerd314, Pascal +Wittmann, Peter Simons, Philip Potter, Preston Bennes, Rommel M. +Martinez, Sander van der Burg, Shea Levy, Tim Cuthbertson, Tuomas +Tynkkynen, Utku Demir and Vladimír Čunát. diff --git a/doc/manual/src/release-notes/rl-1.2.md b/doc/manual/src/release-notes/rl-1.2.md new file mode 100644 index 000000000..25b830955 --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.2.md @@ -0,0 +1,97 @@ +# Release 1.2 (2012-12-06) + +This release has the following improvements and changes: + + - Nix has a new binary substituter mechanism: the *binary cache*. A + binary cache contains pre-built binaries of Nix packages. Whenever + Nix wants to build a missing Nix store path, it will check a set of + binary caches to see if any of them has a pre-built binary of that + path. The configuration setting `binary-caches` contains a list of + URLs of binary caches. For instance, doing + + $ nix-env -i thunderbird --option binary-caches http://cache.nixos.org + + will install Thunderbird and its dependencies, using the available + pre-built binaries in <http://cache.nixos.org>. The main advantage + over the old “manifest”-based method of getting pre-built binaries + is that you don’t have to worry about your manifest being in sync + with the Nix expressions you’re installing from; i.e., you don’t + need to run `nix-pull` to update your manifest. It’s also more + scalable because you don’t need to redownload a giant manifest file + every time. + + A Nix channel can provide a binary cache URL that will be used + automatically if you subscribe to that channel. If you use the + Nixpkgs or NixOS channels (<http://nixos.org/channels>) you + automatically get the cache <http://cache.nixos.org>. + + Binary caches are created using `nix-push`. For details on the + operation and format of binary caches, see the `nix-push` manpage. + More details are provided in [this nix-dev + posting](https://nixos.org/nix-dev/2012-September/009826.html). + + - Multiple output support should now be usable. A derivation can + declare that it wants to produce multiple store paths by saying + something like + + outputs = [ "lib" "headers" "doc" ]; + + This will cause Nix to pass the intended store path of each output + to the builder through the environment variables `lib`, `headers` + and `doc`. Other packages can refer to a specific output by + referring to `pkg.output`, e.g. + + buildInputs = [ pkg.lib pkg.headers ]; + + If you install a package with multiple outputs using `nix-env`, each + output path will be symlinked into the user environment. + + - Dashes are now valid as part of identifiers and attribute names. + + - The new operation `nix-store --repair-path` allows corrupted or + missing store paths to be repaired by redownloading them. `nix-store + --verify --check-contents + --repair` will scan and repair all paths in the Nix store. + Similarly, `nix-env`, `nix-build`, `nix-instantiate` and `nix-store + --realise` have a `--repair` flag to detect and fix bad paths by + rebuilding or redownloading them. + + - Nix no longer sets the immutable bit on files in the Nix store. + Instead, the recommended way to guard the Nix store against + accidental modification on Linux is to make it a read-only bind + mount, like this: + + $ mount --bind /nix/store /nix/store + $ mount -o remount,ro,bind /nix/store + + Nix will automatically make `/nix/store` writable as needed (using a + private mount namespace) to allow modifications. + + - Store optimisation (replacing identical files in the store with hard + links) can now be done automatically every time a path is added to + the store. This is enabled by setting the configuration option + `auto-optimise-store` to `true` (disabled by default). + + - Nix now supports `xz` compression for NARs in addition to `bzip2`. + It compresses about 30% better on typical archives and decompresses + about twice as fast. + + - Basic Nix expression evaluation profiling: setting the environment + variable `NIX_COUNT_CALLS` to `1` will cause Nix to print how many + times each primop or function was executed. + + - New primops: `concatLists`, `elem`, `elemAt` and `filter`. + + - The command `nix-copy-closure` has a new flag `--use-substitutes` + (`-s`) to download missing paths on the target machine using the + substitute mechanism. + + - The command `nix-worker` has been renamed to `nix-daemon`. Support + for running the Nix worker in “slave” mode has been removed. + + - The `--help` flag of every Nix command now invokes `man`. + + - Chroot builds are now supported on systemd machines. + +This release has contributions from Eelco Dolstra, Florian Friesdorf, +Mats Erik Andersson and Shea Levy. diff --git a/doc/manual/src/release-notes/rl-1.3.md b/doc/manual/src/release-notes/rl-1.3.md new file mode 100644 index 000000000..0c7b48380 --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.3.md @@ -0,0 +1,10 @@ +# Release 1.3 (2013-01-04) + +This is primarily a bug fix release. When this version is first run on +Linux, it removes any immutable bits from the Nix store and increases +the schema version of the Nix store. (The previous release removed +support for setting the immutable bit; this release clears any remaining +immutable bits to make certain operations more efficient.) + +This release has contributions from Eelco Dolstra and Stuart +Pernsteiner. diff --git a/doc/manual/src/release-notes/rl-1.4.md b/doc/manual/src/release-notes/rl-1.4.md new file mode 100644 index 000000000..d23de71ad --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.4.md @@ -0,0 +1,22 @@ +# Release 1.4 (2013-02-26) + +This release fixes a security bug in multi-user operation. It was +possible for derivations to cause the mode of files outside of the Nix +store to be changed to 444 (read-only but world-readable) by creating +hard links to those files +([details](https://github.com/NixOS/nix/commit/5526a282b5b44e9296e61e07d7d2626a79141ac4)). + +There are also the following improvements: + + - New built-in function: `builtins.hashString`. + + - Build logs are now stored in `/nix/var/log/nix/drvs/XX/`, where *XX* + is the first two characters of the derivation. This is useful on + machines that keep a lot of build logs (such as Hydra servers). + + - The function `corepkgs/fetchurl` can now make the downloaded file + executable. This will allow getting rid of all bootstrap binaries in + the Nixpkgs source tree. + + - Language change: The expression `"${./path} + ..."` now evaluates to a string instead of a path. diff --git a/doc/manual/src/release-notes/rl-1.5.1.md b/doc/manual/src/release-notes/rl-1.5.1.md new file mode 100644 index 000000000..72b29518e --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.5.1.md @@ -0,0 +1,4 @@ +# Release 1.5.1 (2013-02-28) + +The bug fix to the bug fix had a bug itself, of course. But this time it +will work for sure\! diff --git a/doc/manual/src/release-notes/rl-1.5.2.md b/doc/manual/src/release-notes/rl-1.5.2.md new file mode 100644 index 000000000..508580554 --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.5.2.md @@ -0,0 +1,4 @@ +# Release 1.5.2 (2013-05-13) + +This is primarily a bug fix release. It has contributions from Eelco +Dolstra, Lluís Batlle i Rossell and Shea Levy. diff --git a/doc/manual/src/release-notes/rl-1.5.md b/doc/manual/src/release-notes/rl-1.5.md new file mode 100644 index 000000000..d2ccf8a5d --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.5.md @@ -0,0 +1,4 @@ +# Release 1.5 (2013-02-27) + +This is a brown paper bag release to fix a regression introduced by the +hard link security fix in 1.4. diff --git a/doc/manual/src/release-notes/rl-1.6.1.md b/doc/manual/src/release-notes/rl-1.6.1.md new file mode 100644 index 000000000..9bb9bb1f8 --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.6.1.md @@ -0,0 +1,32 @@ +# Release 1.6.1 (2013-10-28) + +This is primarily a bug fix release. Changes of interest are: + + - Nix 1.6 accidentally changed the semantics of antiquoted paths in + strings, such as `"${/foo}/bar"`. This release reverts to the Nix + 1.5.3 behaviour. + + - Previously, Nix optimised expressions such as `"${expr}"` to *expr*. + Thus it neither checked whether *expr* could be coerced to a string, + nor applied such coercions. This meant that `"${123}"` evaluatued to + `123`, and `"${./foo}"` evaluated to `./foo` (even though `"${./foo} + "` evaluates to `"/nix/store/hash-foo "`). Nix now checks the type + of antiquoted expressions and applies coercions. + + - Nix now shows the exact position of undefined variables. In + particular, undefined variable errors in a `with` previously didn't + show *any* position information, so this makes it a lot easier to + fix such errors. + + - Undefined variables are now treated consistently. Previously, the + `tryEval` function would catch undefined variables inside a `with` + but not outside. Now `tryEval` never catches undefined variables. + + - Bash completion in `nix-shell` now works correctly. + + - Stack traces are less verbose: they no longer show calls to builtin + functions and only show a single line for each derivation on the + call stack. + + - New built-in function: `builtins.typeOf`, which returns the type of + its argument as a string. diff --git a/doc/manual/src/release-notes/rl-1.6.md b/doc/manual/src/release-notes/rl-1.6.md new file mode 100644 index 000000000..9b83d9274 --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.6.md @@ -0,0 +1,72 @@ +# Release 1.6 (2013-09-10) + +In addition to the usual bug fixes, this release has several new +features: + + - The command `nix-build --run-env` has been renamed to `nix-shell`. + + - `nix-shell` now sources `$stdenv/setup` *inside* the interactive + shell, rather than in a parent shell. This ensures that shell + functions defined by `stdenv` can be used in the interactive shell. + + - `nix-shell` has a new flag `--pure` to clear the environment, so you + get an environment that more closely corresponds to the “real” Nix + build. + + - `nix-shell` now sets the shell prompt (`PS1`) to ensure that Nix + shells are distinguishable from your regular shells. + + - `nix-env` no longer requires a `*` argument to match all packages, + so `nix-env -qa` is equivalent to `nix-env + -qa '*'`. + + - `nix-env -i` has a new flag `--remove-all` (`-r`) to remove all + previous packages from the profile. This makes it easier to do + declarative package management similar to NixOS’s + `environment.systemPackages`. For instance, if you have a + specification `my-packages.nix` like this: + + with import <nixpkgs> {}; + [ thunderbird + geeqie + ... + ] + + then after any change to this file, you can run: + + $ nix-env -f my-packages.nix -ir + + to update your profile to match the specification. + + - The ‘`with`’ language construct is now more lazy. It only evaluates + its argument if a variable might actually refer to an attribute in + the argument. For instance, this now works: + + let + pkgs = with pkgs; { foo = "old"; bar = foo; } // overrides; + overrides = { foo = "new"; }; + in pkgs.bar + + This evaluates to `"new"`, while previously it gave an “infinite + recursion” error. + + - Nix now has proper integer arithmetic operators. For instance, you + can write `x + y` instead of `builtins.add x y`, or `x < + y` instead of `builtins.lessThan x y`. The comparison operators also + work on strings. + + - On 64-bit systems, Nix integers are now 64 bits rather than 32 bits. + + - When using the Nix daemon, the `nix-daemon` worker process now runs + on the same CPU as the client, on systems that support setting CPU + affinity. This gives a significant speedup on some systems. + + - If a stack overflow occurs in the Nix evaluator, you now get a + proper error message (rather than “Segmentation fault”) on some + systems. + + - In addition to directories, you can now bind-mount regular files in + chroots through the (now misnamed) option `build-chroot-dirs`. + +This release has contributions from Domen Kožar, Eelco Dolstra, Florian +Friesdorf, Gergely Risko, Ivan Kozik, Ludovic Courtès and Shea Levy. diff --git a/doc/manual/src/release-notes/rl-1.7.md b/doc/manual/src/release-notes/rl-1.7.md new file mode 100644 index 000000000..8d49ae54e --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.7.md @@ -0,0 +1,140 @@ +# Release 1.7 (2014-04-11) + +In addition to the usual bug fixes, this release has the following new +features: + + - Antiquotation is now allowed inside of quoted attribute names (e.g. + `set."${foo}"`). In the case where the attribute name is just a + single antiquotation, the quotes can be dropped (e.g. the above + example can be written `set.${foo}`). If an attribute name inside of + a set declaration evaluates to `null` (e.g. `{ ${null} = false; }`), + then that attribute is not added to the set. + + - Experimental support for cryptographically signed binary caches. See + [the commit for + details](https://github.com/NixOS/nix/commit/0fdf4da0e979f992db75cc17376e455ddc5a96d8). + + - An experimental new substituter, `download-via-ssh`, that fetches + binaries from remote machines via SSH. Specifying the flags + `--option + use-ssh-substituter true --option ssh-substituter-hosts + user@hostname` will cause Nix to download binaries from the + specified machine, if it has them. + + - `nix-store -r` and `nix-build` have a new flag, `--check`, that + builds a previously built derivation again, and prints an error + message if the output is not exactly the same. This helps to verify + whether a derivation is truly deterministic. For example: + + $ nix-build '<nixpkgs>' -A patchelf + … + $ nix-build '<nixpkgs>' -A patchelf --check + … + error: derivation `/nix/store/1ipvxs…-patchelf-0.6' may not be deterministic: + hash mismatch in output `/nix/store/4pc1dm…-patchelf-0.6.drv' + + - The `nix-instantiate` flags `--eval-only` and `--parse-only` have + been renamed to `--eval` and `--parse`, respectively. + + - `nix-instantiate`, `nix-build` and `nix-shell` now have a flag + `--expr` (or `-E`) that allows you to specify the expression to be + evaluated as a command line argument. For instance, `nix-instantiate + --eval -E + '1 + 2'` will print `3`. + + - `nix-shell` improvements: + + - It has a new flag, `--packages` (or `-p`), that sets up a build + environment containing the specified packages from Nixpkgs. For + example, the command + + $ nix-shell -p sqlite xorg.libX11 hello + + will start a shell in which the given packages are present. + + - It now uses `shell.nix` as the default expression, falling back + to `default.nix` if the former doesn’t exist. This makes it + convenient to have a `shell.nix` in your project to set up a + nice development environment. + + - It evaluates the derivation attribute `shellHook`, if set. Since + `stdenv` does not normally execute this hook, it allows you to + do `nix-shell`-specific setup. + + - It preserves the user’s timezone setting. + + - In chroots, Nix now sets up a `/dev` containing only a minimal set + of devices (such as `/dev/null`). Note that it only does this if you + *don’t* have `/dev` listed in your `build-chroot-dirs` setting; + otherwise, it will bind-mount the `/dev` from outside the chroot. + + Similarly, if you don’t have `/dev/pts` listed in + `build-chroot-dirs`, Nix will mount a private `devpts` filesystem on + the chroot’s `/dev/pts`. + + - New built-in function: `builtins.toJSON`, which returns a JSON + representation of a value. + + - `nix-env -q` has a new flag `--json` to print a JSON representation + of the installed or available packages. + + - `nix-env` now supports meta attributes with more complex values, + such as attribute sets. + + - The `-A` flag now allows attribute names with dots in them, e.g. + + $ nix-instantiate --eval '<nixos>' -A 'config.systemd.units."nscd.service".text' + + - The `--max-freed` option to `nix-store --gc` now accepts a unit + specifier. For example, `nix-store --gc --max-freed + 1G` will free up to 1 gigabyte of disk space. + + - `nix-collect-garbage` has a new flag `--delete-older-than` *N*`d`, + which deletes all user environment generations older than *N* days. + Likewise, `nix-env + --delete-generations` accepts a *N*`d` age limit. + + - Nix now heuristically detects whether a build failure was due to a + disk-full condition. In that case, the build is not flagged as + “permanently failed”. This is mostly useful for Hydra, which needs + to distinguish between permanent and transient build failures. + + - There is a new symbol `__curPos` that expands to an attribute set + containing its file name and line and column numbers, e.g. `{ file = + "foo.nix"; line = 10; + column = 5; }`. There also is a new builtin function, + `unsafeGetAttrPos`, that returns the position of an attribute. This + is used by Nixpkgs to provide location information in error + messages, e.g. + + $ nix-build '<nixpkgs>' -A libreoffice --argstr system x86_64-darwin + error: the package ‘libreoffice-4.0.5.2’ in ‘.../applications/office/libreoffice/default.nix:263’ + is not supported on ‘x86_64-darwin’ + + - The garbage collector is now more concurrent with other Nix + processes because it releases certain locks earlier. + + - The binary tarball installer has been improved. You can now install + Nix by running: + + $ bash <(curl https://nixos.org/nix/install) + + - More evaluation errors include position information. For instance, + selecting a missing attribute will print something like + + error: attribute `nixUnstabl' missing, at /etc/nixos/configurations/misc/eelco/mandark.nix:216:15 + + - The command `nix-setuid-helper` is gone. + + - Nix no longer uses Automake, but instead has a non-recursive, GNU + Make-based build system. + + - All installed libraries now have the prefix `libnix`. In particular, + this gets rid of `libutil`, which could clash with libraries with + the same name from other packages. + + - Nix now requires a compiler that supports C++11. + +This release has contributions from Danny Wilson, Domen Kožar, Eelco +Dolstra, Ian-Woo Kim, Ludovic Courtès, Maxim Ivanov, Petr Rockai, +Ricardo M. Correia and Shea Levy. diff --git a/doc/manual/src/release-notes/rl-1.8.md b/doc/manual/src/release-notes/rl-1.8.md new file mode 100644 index 000000000..59af363e8 --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.8.md @@ -0,0 +1,88 @@ +# Release 1.8 (2014-12-14) + + - Breaking change: to address a race condition, the remote build hook + mechanism now uses `nix-store + --serve` on the remote machine. This requires build slaves to be + updated to Nix 1.8. + + - Nix now uses HTTPS instead of HTTP to access the default binary + cache, `cache.nixos.org`. + + - `nix-env` selectors are now regular expressions. For instance, you + can do + + $ nix-env -qa '.*zip.*' + + to query all packages with a name containing `zip`. + + - `nix-store --read-log` can now fetch remote build logs. If a build + log is not available locally, then ‘nix-store -l’ will now try to + download it from the servers listed in the ‘log-servers’ option in + nix.conf. For instance, if you have the configuration option + + log-servers = http://hydra.nixos.org/log + + then it will try to get logs from `http://hydra.nixos.org/log/base + name of the + store path`. This allows you to do things like: + + $ nix-store -l $(which xterm) + + and get a log even if `xterm` wasn't built locally. + + - New builtin functions: `attrValues`, `deepSeq`, `fromJSON`, + `readDir`, `seq`. + + - `nix-instantiate --eval` now has a `--json` flag to print the + resulting value in JSON format. + + - `nix-copy-closure` now uses `nix-store --serve` on the remote side + to send or receive closures. This fixes a race condition between + `nix-copy-closure` and the garbage collector. + + - Derivations can specify the new special attribute + `allowedRequisites`, which has a similar meaning to + `allowedReferences`. But instead of only enforcing to explicitly + specify the immediate references, it requires the derivation to + specify all the dependencies recursively (hence the name, + requisites) that are used by the resulting output. + + - On Mac OS X, Nix now handles case collisions when importing closures + from case-sensitive file systems. This is mostly useful for running + NixOps on Mac OS X. + + - The Nix daemon has new configuration options `allowed-users` + (specifying the users and groups that are allowed to connect to the + daemon) and `trusted-users` (specifying the users and groups that + can perform privileged operations like specifying untrusted binary + caches). + + - The configuration option `build-cores` now defaults to the number of + available CPU cores. + + - Build users are now used by default when Nix is invoked as root. + This prevents builds from accidentally running as root. + + - Nix now includes systemd units and Upstart jobs. + + - Speed improvements to `nix-store + --optimise`. + + - Language change: the `==` operator now ignores string contexts (the + “dependencies” of a string). + + - Nix now filters out Nix-specific ANSI escape sequences on standard + error. They are supposed to be invisible, but some terminals show + them anyway. + + - Various commands now automatically pipe their output into the pager + as specified by the `PAGER` environment variable. + + - Several improvements to reduce memory consumption in the evaluator. + +This release has contributions from Adam Szkoda, Aristid Breitkreuz, Bob +van der Linden, Charles Strahan, darealshinji, Eelco Dolstra, Gergely +Risko, Joel Taylor, Ludovic Courtès, Marko Durkovic, Mikey Ariel, Paul +Colomiets, Ricardo M. Correia, Ricky Elrod, Robert Helgesson, Rob +Vermaas, Russell O'Connor, Shea Levy, Shell Turner, Sönke Hahn, Steve +Purcell, Vladimír Čunát and Wout Mertens. diff --git a/doc/manual/src/release-notes/rl-1.9.md b/doc/manual/src/release-notes/rl-1.9.md new file mode 100644 index 000000000..92c6af90b --- /dev/null +++ b/doc/manual/src/release-notes/rl-1.9.md @@ -0,0 +1,143 @@ +# Release 1.9 (2015-06-12) + +In addition to the usual bug fixes, this release has the following new +features: + + - Signed binary cache support. You can enable signature checking by + adding the following to `nix.conf`: + + signed-binary-caches = * + binary-cache-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= + + This will prevent Nix from downloading any binary from the cache + that is not signed by one of the keys listed in + `binary-cache-public-keys`. + + Signature checking is only supported if you built Nix with the + `libsodium` package. + + Note that while Nix has had experimental support for signed binary + caches since version 1.7, this release changes the signature format + in a backwards-incompatible way. + + - Automatic downloading of Nix expression tarballs. In various places, + you can now specify the URL of a tarball containing Nix expressions + (such as Nixpkgs), which will be downloaded and unpacked + automatically. For example: + + - In `nix-env`: + + $ nix-env -f https://github.com/NixOS/nixpkgs-channels/archive/nixos-14.12.tar.gz -iA firefox + + This installs Firefox from the latest tested and built revision + of the NixOS 14.12 channel. + + - In `nix-build` and `nix-shell`: + + $ nix-build https://github.com/NixOS/nixpkgs/archive/master.tar.gz -A hello + + This builds GNU Hello from the latest revision of the Nixpkgs + master branch. + + - In the Nix search path (as specified via `NIX_PATH` or `-I`). + For example, to start a shell containing the Pan package from a + specific version of Nixpkgs: + + $ nix-shell -p pan -I nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/8a3eea054838b55aca962c3fbde9c83c102b8bf2.tar.gz + + - In `nixos-rebuild` (on NixOS): + + $ nixos-rebuild test -I nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-unstable.tar.gz + + - In Nix expressions, via the new builtin function `fetchTarball`: + + with import (fetchTarball https://github.com/NixOS/nixpkgs-channels/archive/nixos-14.12.tar.gz) {}; … + + (This is not allowed in restricted mode.) + + - `nix-shell` improvements: + + - `nix-shell` now has a flag `--run` to execute a command in the + `nix-shell` environment, e.g. `nix-shell --run make`. This is + like the existing `--command` flag, except that it uses a + non-interactive shell (ensuring that hitting Ctrl-C won’t drop + you into the child shell). + + - `nix-shell` can now be used as a `#!`-interpreter. This allows + you to write scripts that dynamically fetch their own + dependencies. For example, here is a Haskell script that, when + invoked, first downloads GHC and the Haskell packages on which + it depends: + + #! /usr/bin/env nix-shell + #! nix-shell -i runghc -p haskellPackages.ghc haskellPackages.HTTP + + import Network.HTTP + + main = do + resp <- Network.HTTP.simpleHTTP (getRequest "http://nixos.org/") + body <- getResponseBody resp + print (take 100 body) + + Of course, the dependencies are cached in the Nix store, so the + second invocation of this script will be much faster. + + - Chroot improvements: + + - Chroot builds are now supported on Mac OS X (using its sandbox + mechanism). + + - If chroots are enabled, they are now used for all derivations, + including fixed-output derivations (such as `fetchurl`). The + latter do have network access, but can no longer access the host + filesystem. If you need the old behaviour, you can set the + option `build-use-chroot` to `relaxed`. + + - On Linux, if chroots are enabled, builds are performed in a + private PID namespace once again. (This functionality was lost + in Nix 1.8.) + + - Store paths listed in `build-chroot-dirs` are now automatically + expanded to their closure. For instance, if you want + `/nix/store/…-bash/bin/sh` mounted in your chroot as `/bin/sh`, + you only need to say `build-chroot-dirs = + /bin/sh=/nix/store/…-bash/bin/sh`; it is no longer necessary to + specify the dependencies of Bash. + + - The new derivation attribute `passAsFile` allows you to specify that + the contents of derivation attributes should be passed via files + rather than environment variables. This is useful if you need to + pass very long strings that exceed the size limit of the + environment. The Nixpkgs function `writeTextFile` uses this. + + - You can now use `~` in Nix file names to refer to your home + directory, e.g. `import + ~/.nixpkgs/config.nix`. + + - Nix has a new option `restrict-eval` that allows limiting what paths + the Nix evaluator has access to. By passing `--option restrict-eval + true` to Nix, the evaluator will throw an exception if an attempt is + made to access any file outside of the Nix search path. This is + primarily intended for Hydra to ensure that a Hydra jobset only + refers to its declared inputs (and is therefore reproducible). + + - `nix-env` now only creates a new “generation” symlink in + `/nix/var/nix/profiles` if something actually changed. + + - The environment variable `NIX_PAGER` can now be set to override + `PAGER`. You can set it to `cat` to disable paging for Nix commands + only. + + - Failing `<...>` lookups now show position information. + + - Improved Boehm GC use: we disabled scanning for interior pointers, + which should reduce the “`Repeated + allocation of very large block`” warnings and associated retention + of memory. + +This release has contributions from aszlig, Benjamin Staffin, Charles +Strahan, Christian Theune, Daniel Hahler, Danylo Hlynskyi Daniel +Peebles, Dan Peebles, Domen Kožar, Eelco Dolstra, Harald van Dijk, Hoang +Xuan Phu, Jaka Hudoklin, Jeff Ramnani, j-keck, Linquize, Luca Bruno, +Michael Merickel, Oliver Dunkl, Rob Vermaas, Rok Garbas, Shea Levy, +Tobias Geerinckx-Rice and William A. Kennington III. diff --git a/doc/manual/src/release-notes/rl-2.0.md b/doc/manual/src/release-notes/rl-2.0.md new file mode 100644 index 000000000..9f6d4aa83 --- /dev/null +++ b/doc/manual/src/release-notes/rl-2.0.md @@ -0,0 +1,558 @@ +# Release 2.0 (2018-02-22) + +The following incompatible changes have been made: + + - The manifest-based substituter mechanism + (`download-using-manifests`) has been + [removed](https://github.com/NixOS/nix/commit/867967265b80946dfe1db72d40324b4f9af988ed). + It has been superseded by the binary cache substituter mechanism + since several years. As a result, the following programs have been + removed: + + - `nix-pull` + + - `nix-generate-patches` + + - `bsdiff` + + - `bspatch` + + - The “copy from other stores” substituter mechanism + (`copy-from-other-stores` and the `NIX_OTHER_STORES` environment + variable) has been removed. It was primarily used by the NixOS + installer to copy available paths from the installation medium. The + replacement is to use a chroot store as a substituter (e.g. + `--substituters /mnt`), or to build into a chroot store (e.g. + `--store /mnt --substituters /`). + + - The command `nix-push` has been removed as part of the effort to + eliminate Nix's dependency on Perl. You can use `nix copy` instead, + e.g. `nix copy + --to file:///tmp/my-binary-cache paths…` + + - The “nested” log output feature (`--log-type + pretty`) has been removed. As a result, `nix-log2xml` was also + removed. + + - OpenSSL-based signing has been + [removed](https://github.com/NixOS/nix/commit/f435f8247553656774dd1b2c88e9de5d59cab203). + This feature was never well-supported. A better alternative is + provided by the `secret-key-files` and `trusted-public-keys` + options. + + - Failed build caching has been + [removed](https://github.com/NixOS/nix/commit/8cffec84859cec8b610a2a22ab0c4d462a9351ff). + This feature was introduced to support the Hydra continuous build + system, but Hydra no longer uses it. + + - `nix-mode.el` has been removed from Nix. It is now [a separate + repository](https://github.com/NixOS/nix-mode) and can be installed + through the MELPA package repository. + +This release has the following new features: + + - It introduces a new command named `nix`, which is intended to + eventually replace all `nix-*` commands with a more consistent and + better designed user interface. It currently provides replacements + for some (but not all) of the functionality provided by `nix-store`, + `nix-build`, `nix-shell -p`, `nix-env -qa`, `nix-instantiate + --eval`, `nix-push` and `nix-copy-closure`. It has the following + major features: + + - Unlike the legacy commands, it has a consistent way to refer to + packages and package-like arguments (like store paths). For + example, the following commands all copy the GNU Hello package + to a remote machine: + + nix copy --to ssh://machine nixpkgs.hello + + nix copy --to ssh://machine /nix/store/0i2jd68mp5g6h2sa5k9c85rb80sn8hi9-hello-2.10 + + nix copy --to ssh://machine '(with import <nixpkgs> {}; hello)' + + By contrast, `nix-copy-closure` only accepted store paths as + arguments. + + - It is self-documenting: `--help` shows all available + command-line arguments. If `--help` is given after a subcommand, + it shows examples for that subcommand. `nix + --help-config` shows all configuration options. + + - It is much less verbose. By default, it displays a single-line + progress indicator that shows how many packages are left to be + built or downloaded, and (if there are running builds) the most + recent line of builder output. If a build fails, it shows the + last few lines of builder output. The full build log can be + retrieved using `nix + log`. + + - It + [provides](https://github.com/NixOS/nix/commit/b8283773bd64d7da6859ed520ee19867742a03ba) + all `nix.conf` configuration options as command line flags. For + example, instead of `--option + http-connections 100` you can write `--http-connections 100`. + Boolean options can be written as `--foo` or `--no-foo` (e.g. + `--no-auto-optimise-store`). + + - Many subcommands have a `--json` flag to write results to stdout + in JSON format. + + > **Warning** + > + > Please note that the `nix` command is a work in progress and the + > interface is subject to change. + + It provides the following high-level (“porcelain”) subcommands: + + - `nix build` is a replacement for `nix-build`. + + - `nix run` executes a command in an environment in which the + specified packages are available. It is (roughly) a replacement + for `nix-shell + -p`. Unlike that command, it does not execute the command in a + shell, and has a flag (`-c`) that specifies the unquoted command + line to be executed. + + It is particularly useful in conjunction with chroot stores, + allowing Linux users who do not have permission to install Nix + in `/nix/store` to still use binary substitutes that assume + `/nix/store`. For example, + + nix run --store ~/my-nix nixpkgs.hello -c hello --greeting 'Hi everybody!' + + downloads (or if not substitutes are available, builds) the GNU + Hello package into `~/my-nix/nix/store`, then runs `hello` in a + mount namespace where `~/my-nix/nix/store` is mounted onto + `/nix/store`. + + - `nix search` replaces `nix-env + -qa`. It searches the available packages for occurrences of a + search string in the attribute name, package name or + description. Unlike `nix-env -qa`, it has a cache to speed up + subsequent searches. + + - `nix copy` copies paths between arbitrary Nix stores, + generalising `nix-copy-closure` and `nix-push`. + + - `nix repl` replaces the external program `nix-repl`. It provides + an interactive environment for evaluating and building Nix + expressions. Note that it uses `linenoise-ng` instead of GNU + Readline. + + - `nix upgrade-nix` upgrades Nix to the latest stable version. + This requires that Nix is installed in a profile. (Thus it won’t + work on NixOS, or if it’s installed outside of the Nix store.) + + - `nix verify` checks whether store paths are unmodified and/or + “trusted” (see below). It replaces `nix-store --verify` and + `nix-store + --verify-path`. + + - `nix log` shows the build log of a package or path. If the + build log is not available locally, it will try to obtain it + from the configured substituters (such as + [cache.nixos.org](https://cache.nixos.org/), which now + provides build logs). + + - `nix edit` opens the source code of a package in your editor. + + - `nix eval` replaces `nix-instantiate --eval`. + + - `nix + why-depends` shows why one store path has another in its + closure. This is primarily useful to finding the causes of + closure bloat. For example, + + nix why-depends nixpkgs.vlc nixpkgs.libdrm.dev + + shows a chain of files and fragments of file contents that cause + the VLC package to have the “dev” output of `libdrm` in its + closure — an undesirable situation. + + - `nix path-info` shows information about store paths, replacing + `nix-store -q`. A useful feature is the option `--closure-size` + (`-S`). For example, the following command show the closure + sizes of every path in the current NixOS system closure, sorted + by size: + + nix path-info -rS /run/current-system | sort -nk2 + + - `nix optimise-store` replaces `nix-store --optimise`. The main + difference is that it has a progress indicator. + + A number of low-level (“plumbing”) commands are also available: + + - `nix ls-store` and `nix + ls-nar` list the contents of a store path or NAR file. The + former is primarily useful in conjunction with remote stores, + e.g. + + nix ls-store --store https://cache.nixos.org/ -lR /nix/store/0i2jd68mp5g6h2sa5k9c85rb80sn8hi9-hello-2.10 + + lists the contents of path in a binary cache. + + - `nix cat-store` and `nix + cat-nar` allow extracting a file from a store path or NAR file. + + - `nix dump-path` writes the contents of a store path to stdout in + NAR format. This replaces `nix-store --dump`. + + - `nix + show-derivation` displays a store derivation in JSON format. + This is an alternative to `pp-aterm`. + + - `nix + add-to-store` replaces `nix-store + --add`. + + - `nix sign-paths` signs store paths. + + - `nix copy-sigs` copies signatures from one store to another. + + - `nix show-config` shows all configuration options and their + current values. + + - The store abstraction that Nix has had for a long time to support + store access via the Nix daemon has been extended + significantly. In particular, substituters (which used to be + external programs such as `download-from-binary-cache`) are now + subclasses of the abstract `Store` class. This allows many Nix + commands to operate on such store types. For example, `nix + path-info` shows information about paths in your local Nix store, + while `nix path-info --store https://cache.nixos.org/` shows + information about paths in the specified binary cache. Similarly, + `nix-copy-closure`, `nix-push` and substitution are all instances + of the general notion of copying paths between different kinds of + Nix stores. + + Stores are specified using an URI-like syntax, e.g. + <https://cache.nixos.org/> or <ssh://machine>. The following store + types are supported: + + - `LocalStore` (stori URI `local` or an absolute path) and the + misnamed `RemoteStore` (`daemon`) provide access to a local Nix + store, the latter via the Nix daemon. You can use `auto` or the + empty string to auto-select a local or daemon store depending on + whether you have write permission to the Nix store. It is no + longer necessary to set the `NIX_REMOTE` environment variable to + use the Nix daemon. + + As noted above, `LocalStore` now supports chroot builds, + allowing the “physical” location of the Nix store (e.g. + `/home/alice/nix/store`) to differ from its “logical” location + (typically `/nix/store`). This allows non-root users to use Nix + while still getting the benefits from prebuilt binaries from + [cache.nixos.org](https://cache.nixos.org/). + + - `BinaryCacheStore` is the abstract superclass of all binary + cache stores. It supports writing build logs and NAR content + listings in JSON format. + + - `HttpBinaryCacheStore` (`http://`, `https://`) supports binary + caches via HTTP or HTTPS. If the server supports `PUT` requests, + it supports uploading store paths via commands such as `nix + copy`. + + - `LocalBinaryCacheStore` (`file://`) supports binary caches in + the local filesystem. + + - `S3BinaryCacheStore` (`s3://`) supports binary caches stored in + Amazon S3, if enabled at compile time. + + - `LegacySSHStore` (`ssh://`) is used to implement remote builds + and `nix-copy-closure`. + + - `SSHStore` (`ssh-ng://`) supports arbitrary Nix operations on a + remote machine via the same protocol used by `nix-daemon`. + + - Security has been improved in various ways: + + - Nix now stores signatures for local store paths. When paths are + copied between stores (e.g., copied from a binary cache to a + local store), signatures are propagated. + + Locally-built paths are signed automatically using the secret + keys specified by the `secret-key-files` store option. + Secret/public key pairs can be generated using `nix-store + --generate-binary-cache-key`. + + In addition, locally-built store paths are marked as “ultimately + trusted”, but this bit is not propagated when paths are copied + between stores. + + - Content-addressable store paths no longer require signatures — + they can be imported into a store by unprivileged users even if + they lack signatures. + + - The command `nix verify` checks whether the specified paths are + trusted, i.e., have a certain number of trusted signatures, are + ultimately trusted, or are content-addressed. + + - Substitutions from binary caches + [now](https://github.com/NixOS/nix/commit/ecbc3fedd3d5bdc5a0e1a0a51b29062f2874ac8b) + require signatures by default. This was already the case on + NixOS. + + - In Linux sandbox builds, we + [now](https://github.com/NixOS/nix/commit/eba840c8a13b465ace90172ff76a0db2899ab11b) + use `/build` instead of `/tmp` as the temporary build directory. + This fixes potential security problems when a build accidentally + stores its `TMPDIR` in some security-sensitive place, such as an + RPATH. + + - *Pure evaluation mode*. With the `--pure-eval` flag, Nix enables a + variant of the existing restricted evaluation mode that forbids + access to anything that could cause different evaluations of the + same command line arguments to produce a different result. This + includes builtin functions such as `builtins.getEnv`, but more + importantly, *all* filesystem or network access unless a content + hash or commit hash is specified. For example, calls to + `builtins.fetchGit` are only allowed if a `rev` attribute is + specified. + + The goal of this feature is to enable true reproducibility and + traceability of builds (including NixOS system configurations) at + the evaluation level. For example, in the future, `nixos-rebuild` + might build configurations from a Nix expression in a Git repository + in pure mode. That expression might fetch other repositories such as + Nixpkgs via `builtins.fetchGit`. The commit hash of the top-level + repository then uniquely identifies a running system, and, in + conjunction with that repository, allows it to be reproduced or + modified. + + - There are several new features to support binary reproducibility + (i.e. to help ensure that multiple builds of the same derivation + produce exactly the same output). When `enforce-determinism` is set + to `false`, it’s [no + longer](https://github.com/NixOS/nix/commit/8bdf83f936adae6f2c907a6d2541e80d4120f051) + a fatal error if build rounds produce different output. Also, a hook + named `diff-hook` is + [provided](https://github.com/NixOS/nix/commit/9a313469a4bdea2d1e8df24d16289dc2a172a169) + to allow you to run tools such as `diffoscope` when build rounds + produce different output. + + - Configuring remote builds is a lot easier now. Provided you are not + using the Nix daemon, you can now just specify a remote build + machine on the command line, e.g. `--option builders + 'ssh://my-mac x86_64-darwin'`. The environment variable + `NIX_BUILD_HOOK` has been removed and is no longer needed. The + environment variable `NIX_REMOTE_SYSTEMS` is still supported for + compatibility, but it is also possible to specify builders in + `nix.conf` by setting the option `builders = + @path`. + + - If a fixed-output derivation produces a result with an incorrect + hash, the output path is moved to the location corresponding to the + actual hash and registered as valid. Thus, a subsequent build of the + fixed-output derivation with the correct hash is unnecessary. + + - `nix-shell` + [now](https://github.com/NixOS/nix/commit/ea59f39326c8e9dc42dfed4bcbf597fbce58797c) + sets the `IN_NIX_SHELL` environment variable during evaluation and + in the shell itself. This can be used to perform different actions + depending on whether you’re in a Nix shell or in a regular build. + Nixpkgs provides `lib.inNixShell` to check this variable during + evaluation. + + - `NIX_PATH` is now lazy, so URIs in the path are only downloaded if + they are needed for evaluation. + + - You can now use `channel:` as a short-hand for + <https://nixos.org/channels//nixexprs.tar.xz>. For example, + `nix-build channel:nixos-15.09 -A hello` will build the GNU Hello + package from the `nixos-15.09` channel. In the future, this may + use Git to fetch updates more efficiently. + + - When `--no-build-output` is given, the last 10 lines of the build + log will be shown if a build fails. + + - Networking has been improved: + + - HTTP/2 is now supported. This makes binary cache lookups [much + more + efficient](https://github.com/NixOS/nix/commit/90ad02bf626b885a5dd8967894e2eafc953bdf92). + + - We now retry downloads on many HTTP errors, making binary caches + substituters more resilient to temporary failures. + + - HTTP credentials can now be configured via the standard `netrc` + mechanism. + + - If S3 support is enabled at compile time, <s3://> URIs are + [supported](https://github.com/NixOS/nix/commit/9ff9c3f2f80ba4108e9c945bbfda2c64735f987b) + in all places where Nix allows URIs. + + - Brotli compression is now supported. In particular, + [cache.nixos.org](https://cache.nixos.org/) build logs are now compressed + using Brotli. + + - `nix-env` + [now](https://github.com/NixOS/nix/commit/b0cb11722626e906a73f10dd9a0c9eea29faf43a) + ignores packages with bad derivation names (in particular those + starting with a digit or containing a dot). + + - Many configuration options have been renamed, either because they + were unnecessarily verbose (e.g. `build-use-sandbox` is now just + `sandbox`) or to reflect generalised behaviour (e.g. `binary-caches` + is now `substituters` because it allows arbitrary store URIs). The + old names are still supported for compatibility. + + - The `max-jobs` option can + [now](https://github.com/NixOS/nix/commit/7251d048fa812d2551b7003bc9f13a8f5d4c95a5) + be set to `auto` to use the number of CPUs in the system. + + - Hashes can + [now](https://github.com/NixOS/nix/commit/c0015e87af70f539f24d2aa2bc224a9d8b84276b) + be specified in base-64 format, in addition to base-16 and the + non-standard base-32. + + - `nix-shell` now uses `bashInteractive` from Nixpkgs, rather than the + `bash` command that happens to be in the caller’s `PATH`. This is + especially important on macOS where the `bash` provided by the + system is seriously outdated and cannot execute `stdenv`’s setup + script. + + - Nix can now automatically trigger a garbage collection if free disk + space drops below a certain level during a build. This is configured + using the `min-free` and `max-free` options. + + - `nix-store -q --roots` and `nix-store --gc --print-roots` now show + temporary and in-memory roots. + + - Nix can now be extended with plugins. See the documentation of the + `plugin-files` option for more details. + +The Nix language has the following new features: + + - It supports floating point numbers. They are based on the C++ + `float` type and are supported by the existing numerical operators. + Export and import to and from JSON and XML works, too. + + - Derivation attributes can now reference the outputs of the + derivation using the `placeholder` builtin function. For example, + the attribute + + configureFlags = "--prefix=${placeholder "out"} --includedir=${placeholder "dev"}"; + + will cause the `configureFlags` environment variable to contain the + actual store paths corresponding to the `out` and `dev` outputs. + +The following builtin functions are new or extended: + + - `builtins.fetchGit` allows Git repositories to be fetched at + evaluation time. Thus it differs from the `fetchgit` function in + Nixpkgs, which fetches at build time and cannot be used to fetch Nix + expressions during evaluation. A typical use case is to import + external NixOS modules from your configuration, e.g. + + imports = [ (builtins.fetchGit https://github.com/edolstra/dwarffs + "/module.nix") ]; + + - Similarly, `builtins.fetchMercurial` allows you to fetch Mercurial + repositories. + + - `builtins.path` generalises `builtins.filterSource` and path + literals (e.g. `./foo`). It allows specifying a store path name that + differs from the source path name (e.g. `builtins.path { path = + ./foo; name = "bar"; + }`) and also supports filtering out unwanted files. + + - `builtins.fetchurl` and `builtins.fetchTarball` now support `sha256` + and `name` attributes. + + - `builtins.split` splits a string using a POSIX extended regular + expression as the separator. + + - `builtins.partition` partitions the elements of a list into two + lists, depending on a Boolean predicate. + + - `<nix/fetchurl.nix>` now uses the content-addressable tarball cache + at <http://tarballs.nixos.org/>, just like `fetchurl` in Nixpkgs. + (f2682e6e18a76ecbfb8a12c17e3a0ca15c084197) + + - In restricted and pure evaluation mode, builtin functions that + download from the network (such as `fetchGit`) are permitted to + fetch underneath a list of URI prefixes specified in the option + `allowed-uris`. + +The Nix build environment has the following changes: + + - Values such as Booleans, integers, (nested) lists and attribute sets + can + [now](https://github.com/NixOS/nix/commit/6de33a9c675b187437a2e1abbcb290981a89ecb1) + be passed to builders in a non-lossy way. If the special attribute + `__structuredAttrs` is set to `true`, the other derivation + attributes are serialised in JSON format and made available to the + builder via the file `.attrs.json` in the builder’s temporary + directory. This obviates the need for `passAsFile` since JSON files + have no size restrictions, unlike process environments. + + [As a convenience to Bash + builders](https://github.com/NixOS/nix/commit/2d5b1b24bf70a498e4c0b378704cfdb6471cc699), + Nix writes a script named `.attrs.sh` to the builder’s directory + that initialises shell variables corresponding to all attributes + that are representable in Bash. This includes non-nested + (associative) arrays. For example, the attribute `hardening.format = + true` ends up as the Bash associative array element + `${hardening[format]}`. + + - Builders can + [now](https://github.com/NixOS/nix/commit/88e6bb76de5564b3217be9688677d1c89101b2a3) + communicate what build phase they are in by writing messages to the + file descriptor specified in `NIX_LOG_FD`. The current phase is + shown by the `nix` progress indicator. + + - In Linux sandbox builds, we + [now](https://github.com/NixOS/nix/commit/a2d92bb20e82a0957067ede60e91fab256948b41) + provide a default `/bin/sh` (namely `ash` from BusyBox). + + - In structured attribute mode, `exportReferencesGraph` + [exports](https://github.com/NixOS/nix/commit/c2b0d8749f7e77afc1c4b3e8dd36b7ee9720af4a) + extended information about closures in JSON format. In particular, + it includes the sizes and hashes of paths. This is primarily useful + for NixOS image builders. + + - Builds are + [now](https://github.com/NixOS/nix/commit/21948deed99a3295e4d5666e027a6ca42dc00b40) + killed as soon as Nix receives EOF on the builder’s stdout or + stderr. This fixes a bug that allowed builds to hang Nix + indefinitely, regardless of timeouts. + + - The `sandbox-paths` configuration option can now specify optional + paths by appending a `?`, e.g. `/dev/nvidiactl?` will bind-mount + `/dev/nvidiactl` only if it exists. + + - On Linux, builds are now executed in a user namespace with UID 1000 + and GID 100. + +A number of significant internal changes were made: + + - Nix no longer depends on Perl and all Perl components have been + rewritten in C++ or removed. The Perl bindings that used to be part + of Nix have been moved to a separate package, `nix-perl`. + + - All `Store` classes are now thread-safe. `RemoteStore` supports + multiple concurrent connections to the daemon. This is primarily + useful in multi-threaded programs such as `hydra-queue-runner`. + +This release has contributions from Adrien Devresse, Alexander Ried, +Alex Cruice, Alexey Shmalko, AmineChikhaoui, Andy Wingo, Aneesh Agrawal, +Anthony Cowley, Armijn Hemel, aszlig, Ben Gamari, Benjamin Hipple, +Benjamin Staffin, Benno Fünfstück, Bjørn Forsman, Brian McKenna, Charles +Strahan, Chase Adams, Chris Martin, Christian Theune, Chris Warburton, +Daiderd Jordan, Dan Connolly, Daniel Peebles, Dan Peebles, davidak, +David McFarland, Dmitry Kalinkin, Domen Kožar, Eelco Dolstra, Emery +Hemingway, Eric Litak, Eric Wolf, Fabian Schmitthenner, Frederik +Rietdijk, Gabriel Gonzalez, Giorgio Gallo, Graham Christensen, Guillaume +Maudoux, Harmen, Iavael, James Broadhead, James Earl Douglas, Janus +Troelsen, Jeremy Shaw, Joachim Schiele, Joe Hermaszewski, Joel Moberg, +Johannes 'fish' Ziemke, Jörg Thalheim, Jude Taylor, kballou, Keshav +Kini, Kjetil Orbekk, Langston Barrett, Linus Heckemann, Ludovic Courtès, +Manav Rathi, Marc Scholten, Markus Hauck, Matt Audesse, Matthew Bauer, +Matthias Beyer, Matthieu Coudron, N1X, Nathan Zadoks, Neil Mayhew, +Nicolas B. Pierron, Niklas Hambüchen, Nikolay Amiantov, Ole Jørgen +Brønner, Orivej Desh, Peter Simons, Peter Stuart, Pyry Jahkola, regnat, +Renzo Carbonara, Rhys, Robert Vollmert, Scott Olson, Scott R. Parish, +Sergei Trofimovich, Shea Levy, Sheena Artrip, Spencer Baugh, Stefan +Junker, Susan Potter, Thomas Tuegel, Timothy Allen, Tristan Hume, Tuomas +Tynkkynen, tv, Tyson Whitehead, Vladimír Čunát, Will Dietz, wmertens, +Wout Mertens, zimbatm and Zoran Plesivčak. diff --git a/doc/manual/src/release-notes/rl-2.1.md b/doc/manual/src/release-notes/rl-2.1.md new file mode 100644 index 000000000..b88834c83 --- /dev/null +++ b/doc/manual/src/release-notes/rl-2.1.md @@ -0,0 +1,49 @@ +# Release 2.1 (2018-09-02) + +This is primarily a bug fix release. It also reduces memory consumption +in certain situations. In addition, it has the following new features: + + - The Nix installer will no longer default to the Multi-User + installation for macOS. You can still instruct the installer to + run in multi-user mode. + + - The Nix installer now supports performing a Multi-User + installation for Linux computers which are running systemd. You + can select a Multi-User installation by passing the `--daemon` + flag to the installer: `sh <(curl https://nixos.org/nix/install) + --daemon`. + + The multi-user installer cannot handle systems with SELinux. If + your system has SELinux enabled, you can force the installer to + run in single-user mode. + + - New builtin functions: `builtins.bitAnd`, `builtins.bitOr`, + `builtins.bitXor`, `builtins.fromTOML`, `builtins.concatMap`, + `builtins.mapAttrs`. + + - The S3 binary cache store now supports uploading NARs larger than 5 + GiB. + + - The S3 binary cache store now supports uploading to S3-compatible + services with the `endpoint` option. + + - The flag `--fallback` is no longer required to recover from + disappeared NARs in binary caches. + + - `nix-daemon` now respects `--store`. + + - `nix run` now respects `nix-support/propagated-user-env-packages`. + +This release has contributions from Adrien Devresse, Aleksandr Pashkov, +Alexandre Esteves, Amine Chikhaoui, Andrew Dunham, Asad Saeeduddin, +aszlig, Ben Challenor, Ben Gamari, Benjamin Hipple, Bogdan Seniuc, Corey +O'Connor, Daiderd Jordan, Daniel Peebles, Daniel Poelzleithner, Danylo +Hlynskyi, Dmitry Kalinkin, Domen Kožar, Doug Beardsley, Eelco Dolstra, +Erik Arvstedt, Félix Baylac-Jacqué, Gleb Peregud, Graham Christensen, +Guillaume Maudoux, Ivan Kozik, John Arnold, Justin Humm, Linus +Heckemann, Lorenzo Manacorda, Matthew Justin Bauer, Matthew O'Gorman, +Maximilian Bosch, Michael Bishop, Michael Fiano, Michael Mercier, +Michael Raskin, Michael Weiss, Nicolas Dudebout, Peter Simons, Ryan +Trinkle, Samuel Dionne-Riel, Sean Seefried, Shea Levy, Symphorien Gibol, +Tim Engler, Tim Sears, Tuomas Tynkkynen, volth, Will Dietz, Yorick van +Pelt and zimbatm. diff --git a/doc/manual/src/release-notes/rl-2.2.md b/doc/manual/src/release-notes/rl-2.2.md new file mode 100644 index 000000000..b67d65db7 --- /dev/null +++ b/doc/manual/src/release-notes/rl-2.2.md @@ -0,0 +1,82 @@ +# Release 2.2 (2019-01-11) + +This is primarily a bug fix release. It also has the following changes: + + - In derivations that use structured attributes (i.e. that specify set + the `__structuredAttrs` attribute to `true` to cause all attributes + to be passed to the builder in JSON format), you can now specify + closure checks per output, e.g.: + + outputChecks."out" = { + # The closure of 'out' must not be larger than 256 MiB. + maxClosureSize = 256 * 1024 * 1024; + + # It must not refer to C compiler or to the 'dev' output. + disallowedRequisites = [ stdenv.cc "dev" ]; + }; + + outputChecks."dev" = { + # The 'dev' output must not be larger than 128 KiB. + maxSize = 128 * 1024; + }; + + - The derivation attribute `requiredSystemFeatures` is now enforced + for local builds, and not just to route builds to remote builders. + The supported features of a machine can be specified through the + configuration setting `system-features`. + + By default, `system-features` includes `kvm` if `/dev/kvm` exists. + For compatibility, it also includes the pseudo-features + `nixos-test`, `benchmark` and `big-parallel` which are used by + Nixpkgs to route builds to particular Hydra build machines. + + - Sandbox builds are now enabled by default on Linux. + + - The new command `nix doctor` shows potential issues with your Nix + installation. + + - The `fetchGit` builtin function now uses a caching scheme that puts + different remote repositories in distinct local repositories, rather + than a single shared repository. This may require more disk space + but is faster. + + - The `dirOf` builtin function now works on relative paths. + + - Nix now supports [SRI hashes](https://www.w3.org/TR/SRI/), allowing + the hash algorithm and hash to be specified in a single string. For + example, you can write: + + import <nix/fetchurl.nix> { + url = https://nixos.org/releases/nix/nix-2.1.3/nix-2.1.3.tar.xz; + hash = "sha256-XSLa0FjVyADWWhFfkZ2iKTjFDda6mMXjoYMXLRSYQKQ="; + }; + + instead of + + import <nix/fetchurl.nix> { + url = https://nixos.org/releases/nix/nix-2.1.3/nix-2.1.3.tar.xz; + sha256 = "5d22dad058d5c800d65a115f919da22938c50dd6ba98c5e3a183172d149840a4"; + }; + + In fixed-output derivations, the `outputHashAlgo` attribute is no + longer mandatory if `outputHash` specifies the hash. + + `nix hash-file` and `nix + hash-path` now print hashes in SRI format by default. They also use + SHA-256 by default instead of SHA-512 because that's what we use + most of the time in Nixpkgs. + + - Integers are now 64 bits on all platforms. + + - The evaluator now prints profiling statistics (enabled via the + `NIX_SHOW_STATS` and `NIX_COUNT_CALLS` environment variables) in + JSON format. + + - The option `--xml` in `nix-store + --query` has been removed. Instead, there now is an option + `--graphml` to output the dependency graph in GraphML format. + + - All `nix-*` commands are now symlinks to `nix`. This saves a bit of + disk space. + + - `nix repl` now uses `libeditline` or `libreadline`. diff --git a/doc/manual/src/release-notes/rl-2.3.md b/doc/manual/src/release-notes/rl-2.3.md new file mode 100644 index 000000000..d1f4e3734 --- /dev/null +++ b/doc/manual/src/release-notes/rl-2.3.md @@ -0,0 +1,44 @@ +# Release 2.3 (2019-09-04) + +This is primarily a bug fix release. However, it makes some incompatible +changes: + + - Nix now uses BSD file locks instead of POSIX file locks. Because of + this, you should not use Nix 2.3 and previous releases at the same + time on a Nix store. + +It also has the following changes: + + - `builtins.fetchGit`'s `ref` argument now allows specifying an + absolute remote ref. Nix will automatically prefix `ref` with + `refs/heads` only if `ref` doesn't already begin with `refs/`. + + - The installer now enables sandboxing by default on Linux when the + system has the necessary kernel support. + + - The `max-jobs` setting now defaults to 1. + + - New builtin functions: `builtins.isPath`, `builtins.hashFile`. + + - The `nix` command has a new `--print-build-logs` (`-L`) flag to + print build log output to stderr, rather than showing the last log + line in the progress bar. To distinguish between concurrent builds, + log lines are prefixed by the name of the package. + + - Builds are now executed in a pseudo-terminal, and the `TERM` + environment variable is set to `xterm-256color`. This allows many + programs (e.g. `gcc`, `clang`, `cmake`) to print colorized log + output. + + - Add `--no-net` convenience flag. This flag disables substituters; + sets the `tarball-ttl` setting to infinity (ensuring that any + previously downloaded files are considered current); and disables + retrying downloads and sets the connection timeout to the minimum. + This flag is enabled automatically if there are no configured + non-loopback network interfaces. + + - Add a `post-build-hook` setting to run a program after a build has + succeeded. + + - Add a `trace-function-calls` setting to log the duration of Nix + function calls to stderr. |
