mirror of
https://github.com/privatevoid-net/nix-super.git
synced 2024-11-15 18:56:16 +02:00
53 lines
2.4 KiB
Markdown
53 lines
2.4 KiB
Markdown
|
# Default Nix expression
|
||
|
|
|
||
|
|
The source for the default [Nix expressions](@docroot@/language/index.md) used by [`nix-env`].
|
||
|
|
|
||
|
|
- `~/.nix-defexpr`
|
||
|
|
- `$XDG_STATE_HOME/nix/defexpr` if [`use-xdg-base-directories`] is set to `true`.
|
||
|
|
|
||
|
|
It is loaded as follows:
|
||
|
|
|
||
|
|
- If the default expression is a file, it is loaded as a Nix expression.
|
||
|
|
- If the default expression is a directory containing a `default.nix` file, that `default.nix` file is loaded as a Nix expression.
|
||
|
|
- If the default expression 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 attribute set, each expression under an attribute with the same name as the original file or subdirectory.
|
||
|
|
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.
|
||
|
|
|
||
|
|
Then, the resulting expression is interpreted like this:
|
||
|
|
|
||
|
|
- If the expression is an attribute 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.
|
||
|
|
|
||
|
|
|
||
|
|
For example, if the default expression contains two files, `foo.nix` and `bar.nix`, then the default Nix expression will be equivalent to
|
||
|
|
|
||
|
|
```nix
|
||
|
|
{
|
||
|
|
foo = import ~/.nix-defexpr/foo.nix;
|
||
|
|
bar = import ~/.nix-defexpr/bar.nix;
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
The file `manifest.nix` is always ignored.
|
||
|
|
|
||
|
|
The command [`nix-channel`] places a symlink to the user's current [channels profile](@docroot@/command-ref/files/channels.md) in this directory.
|
||
|
|
This makes all subscribed channels available as attributes in the default expression.
|
||
|
|
|
||
|
|
## User channel link
|
||
|
|
|
||
|
|
A symlink that ensures that [`nix-env`] can find your channels.
|
||
|
|
|
||
|
|
- `~/.nix-defexpr/channels`
|
||
|
|
- `$XDG_STATE_HOME/defexpr/channels` if [`use-xdg-base-directories`] is set to `true`.
|
||
|
|
|
||
|
|
This symlink points to:
|
||
|
|
|
||
|
|
- `$XDG_STATE_HOME/profiles/channels` for regular users
|
||
|
|
- `$NIX_STATE_DIR/profiles/per-user/root/channels` for `root`
|
||
|
|
|
||
|
|
In a multi-user installation, you may also have `~/.nix-defexpr/channels_root`, which links to the channels of the root user.[`nix-env`]: ../nix-env.md
|
||
|
|
|
||
|
|
[`nix-env`]: @docroot@/command-ref/nix-env.md
|
||
|
|
[`nix-channel`]: @docroot@/command-ref/nix-channel.md
|
||
|
|
[`use-xdg-base-directories`]: @docroot@/command-ref/conf-file.md#conf-use-xdg-base-directories
|