1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
|
R""(
# Examples
* Create a new flake:
```console
# nix flake new hello
# cd hello
```
* Build the flake in the current directory:
```console
# nix build
# ./result/bin/hello
Hello, world!
```
* Run the flake in the current directory:
```console
# nix run
Hello, world!
```
* Start a development shell for hacking on this flake:
```console
# nix develop
# unpackPhase
# cd hello-*
# configurePhase
# buildPhase
# ./hello
Hello, world!
# installPhase
# ../outputs/out/bin/hello
Hello, world!
```
# Description
Nix is a tool for building software, configurations and other
artifacts in a reproducible and declarative way. For more information,
see the [Nix homepage](https://nixos.org/) or the [Nix
manual](https://nixos.org/manual/nix/stable/).
# Installables
Many `nix` subcommands operate on one or more *installables*. These are
command line arguments that represent something that can be built in
the Nix store. Here are the recognised types of installables:
* **Flake output attributes**: `nixpkgs#hello`
These have the form *flakeref*[`#`*attrpath*], where *flakeref* is a
flake reference and *attrpath* is an optional attribute path. For
more information on flakes, see [the `nix flake` manual
page](./nix3-flake.md). Flake references are most commonly a flake
identifier in the flake registry (e.g. `nixpkgs`), or a raw path
(e.g. `/path/to/my-flake` or `.` or `../foo`), or a full URL
(e.g. `github:nixos/nixpkgs` or `path:.`)
When the flake reference is a raw path (a path without any URL
scheme), it is interpreted as a `path:` or `git+file:` url in the following
way:
- If the path is within a Git repository, then the url will be of the form
`git+file://[GIT_REPO_ROOT]?dir=[RELATIVE_FLAKE_DIR_PATH]`
where `GIT_REPO_ROOT` is the path to the root of the git repository,
and `RELATIVE_FLAKE_DIR_PATH` is the path (relative to the directory
root) of the closest parent of the given path that contains a `flake.nix` within
the git repository.
If no such directory exists, then Nix will error-out.
Note that the search will only include files indexed by git. In particular, files
which are matched by `.gitignore` or have never been `git add`-ed will not be
available in the flake. If this is undesirable, specify `path:<directory>` explicitly;
For example, if `/foo/bar` is a git repository with the following structure:
```
.
└── baz
├── blah
│ └── file.txt
└── flake.nix
```
Then `/foo/bar/baz/blah` will resolve to `git+file:///foo/bar?dir=baz`
- If the supplied path is not a git repository, then the url will have the form
`path:FLAKE_DIR_PATH` where `FLAKE_DIR_PATH` is the closest parent
of the supplied path that contains a `flake.nix` file (within the same file-system).
If no such directory exists, then Nix will error-out.
For example, if `/foo/bar/flake.nix` exists, then `/foo/bar/baz/` will resolve to
`path:/foo/bar`
If *attrpath* is omitted, Nix tries some default values; for most
subcommands, the default is `packages.`*system*`.default`
(e.g. `packages.x86_64-linux.default`), but some subcommands have
other defaults. If *attrpath* *is* specified, *attrpath* is
interpreted as relative to one or more prefixes; for most
subcommands, these are `packages.`*system*,
`legacyPackages.*system*` and the empty prefix. Thus, on
`x86_64-linux` `nix build nixpkgs#hello` will try to build the
attributes `packages.x86_64-linux.hello`,
`legacyPackages.x86_64-linux.hello` and `hello`.
* **Store paths**: `/nix/store/v5sv61sszx301i0x6xysaqzla09nksnd-hello-2.10`
These are paths inside the Nix store, or symlinks that resolve to a
path in the Nix store.
* **Store derivations**: `/nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv`
Store derivations are store paths with extension `.drv` and are a
low-level representation of a build-time dependency graph used
internally by Nix. By default, if you pass a store derivation to a
`nix` subcommand, it will operate on the *output paths* of the
derivation. For example, `nix path-info` prints information about
the output paths:
```console
# nix path-info --json /nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv
[{"path":"/nix/store/v5sv61sszx301i0x6xysaqzla09nksnd-hello-2.10",…}]
```
If you want to operate on the store derivation itself, pass the
`--derivation` flag.
* **Nix attributes**: `--file /path/to/nixpkgs hello`
When the `-f` / `--file` *path* option is given, installables are
interpreted as attribute paths referencing a value returned by
evaluating the Nix file *path*.
* **Nix expressions**: `--expr '(import <nixpkgs> {}).hello.overrideDerivation (prev: { name = "my-hello"; })'`.
When the `--expr` option is given, all installables are interpreted
as Nix expressions. You may need to specify `--impure` if the
expression references impure inputs (such as `<nixpkgs>`).
For most commands, if no installable is specified, the default is `.`,
i.e. Nix will operate on the default flake output attribute of the
flake in the current directory.
# Nix stores
Most `nix` subcommands operate on a *Nix store*.
TODO: list store types, options
)""
|
