blob: 1404289e50afe4229ad0317e0e14efa88a27cc36 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
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"`.
|
