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
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
|
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 realised in the Nix store.
The following types of installable are supported by most commands:
- [Flake output attribute](#flake-output-attribute)
- [Store path](#store-path)
- [Nix file](#nix-file), optionally qualified by an attribute path
- [Nix expression](#nix-expression), optionally qualified by an attribute path
For most commands, if no installable is specified, `.` as assumed.
That is, Nix will operate on the default flake output attribute of the flake in the current directory.
### Flake output attribute
Example: `nixpkgs#hello`
These have the form *flakeref*[`#`*attrpath*], where *flakeref* is a
[flake reference](./nix3-flake.md#flake-references) 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 path
Example: `/nix/store/v5sv61sszx301i0x6xysaqzla09nksnd-hello-2.10`
These are paths inside the Nix store, or symlinks that resolve to a path in the Nix store.
A [store derivation] is also addressed by store path.
Example: `/nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv`
If you want to refer to an output path of that store derivation, add the output name preceded by a caret (`^`).
Example: `/nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv^out`
All outputs can be referred to at once with the special syntax `^*`.
Example: `/nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv^*`
### Nix file
Example: `--file /path/to/nixpkgs hello`
When the option `-f` / `--file` *path* \[*attrpath*...\] is given, installables are interpreted as the value of the expression in the Nix file at *path*.
If attribute paths are provided, commands will operate on the corresponding values accessible at these paths.
The Nix expression in that file, or any selected attribute, must evaluate to a derivation.
### Nix expression
Example: `--expr 'import <nixpkgs> {}' hello`
When the option `--expr` *expression* \[*attrpath*...\] is given, installables are interpreted as the value of the of the Nix expression.
If attribute paths are provided, commands will operate on the corresponding values accessible at these paths.
The Nix expression, or any selected attribute, must evaluate to a derivation.
You may need to specify `--impure` if the expression references impure inputs (such as `<nixpkgs>`).
## Derivation output selection
Derivations can have multiple outputs, each corresponding to a
different store path. For instance, a package can have a `bin` output
that contains programs, and a `dev` output that provides development
artifacts like C/C++ header files. The outputs on which `nix` commands
operate are determined as follows:
* You can explicitly specify the desired outputs using the syntax
*installable*`^`*output1*`,`*...*`,`*outputN*. For example, you can
obtain the `dev` and `static` outputs of the `glibc` package:
```console
# nix build 'nixpkgs#glibc^dev,static'
# ls ./result-dev/include/ ./result-static/lib/
…
```
and likewise, using a store path to a "drv" file to specify the derivation:
```console
# nix build '/nix/store/gzaflydcr6sb3567hap9q6srzx8ggdgg-glibc-2.33-78.drv^dev,static'
…
```
* You can also specify that *all* outputs should be used using the
syntax *installable*`^*`. For example, the following shows the size
of all outputs of the `glibc` package in the binary cache:
```console
# nix path-info -S --eval-store auto --store https://cache.nixos.org 'nixpkgs#glibc^*'
/nix/store/g02b1lpbddhymmcjb923kf0l7s9nww58-glibc-2.33-123 33208200
/nix/store/851dp95qqiisjifi639r0zzg5l465ny4-glibc-2.33-123-bin 36142896
/nix/store/kdgs3q6r7xdff1p7a9hnjr43xw2404z7-glibc-2.33-123-debug 155787312
/nix/store/n4xa8h6pbmqmwnq0mmsz08l38abb06zc-glibc-2.33-123-static 42488328
/nix/store/q6580lr01jpcsqs4r5arlh4ki2c1m9rv-glibc-2.33-123-dev 44200560
```
and likewise, using a store path to a "drv" file to specify the derivation:
```console
# nix path-info -S '/nix/store/gzaflydcr6sb3567hap9q6srzx8ggdgg-glibc-2.33-78.drv^*'
…
```
* If you didn't specify the desired outputs, but the derivation has an
attribute `meta.outputsToInstall`, Nix will use those outputs. For
example, since the package `nixpkgs#libxml2` has this attribute:
```console
# nix eval 'nixpkgs#libxml2.meta.outputsToInstall'
[ "bin" "man" ]
```
a command like `nix shell nixpkgs#libxml2` will provide only those
two outputs by default.
Note that a [store derivation] (given by its `.drv` file store path) doesn't have
any attributes like `meta`, and thus this case doesn't apply to it.
[store derivation]: ../../glossary.md#gloss-store-derivation
* Otherwise, Nix will use all outputs of the derivation.
# Nix stores
Most `nix` subcommands operate on a *Nix store*. These are documented
in [`nix help-stores`](./nix3-help-stores.md).
)""
|
