diff options
Diffstat (limited to 'doc/manual/src/command-ref/nix-store.md')
| -rw-r--r-- | doc/manual/src/command-ref/nix-store.md | 833 |
1 files changed, 833 insertions, 0 deletions
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..7a131dc02 --- /dev/null +++ b/doc/manual/src/command-ref/nix-store.md @@ -0,0 +1,833 @@ +# 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) + substitutes, 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` settings 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. |