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Diffstat (limited to 'src')
| -rw-r--r-- | src/doc/unstable-book/src/compiler-flags/env.md | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/src/doc/unstable-book/src/compiler-flags/env.md b/src/doc/unstable-book/src/compiler-flags/env.md new file mode 100644 index 00000000000..df0547dd24b --- /dev/null +++ b/src/doc/unstable-book/src/compiler-flags/env.md @@ -0,0 +1,26 @@ +# `env` + +The tracking issue for this feature is: [#118372](https://github.com/rust-lang/rust/issues/118372). + +------------------------ + +This option flag allows to specify environment variables value at compile time to be +used by `env!` and `option_env!` macros. + +When retrieving an environment variable value, the one specified by `--env` will take +precedence. For example, if you want have `PATH=a` in your environment and pass: + +```bash +rustc --env PATH=env +``` + +Then you will have: + +```rust,no_run +assert_eq!(env!("PATH"), "env"); +``` + +Please note that on Windows, environment variables are case insensitive but case +preserving whereas `rustc`'s environment variables are case sensitive. For example, +having `Path` in your environment (case insensitive) is different than using +`rustc --env Path=...` (case sensitive). |