Function tracing_core::stdlib::env::var_os
1.0.0 · source · pub fn var_os<K>(key: K) -> Option<OsString>
Expand description
Fetches the environment variable key
from the current process, returning
None
if the variable isn’t set or if there is another error.
It may return None
if the environment variable’s name contains
the equal sign character (=
) or the NUL character.
Note that this function will not check if the environment variable
is valid Unicode. If you want to have an error on invalid UTF-8,
use the var
function instead.
§Examples
use std::env;
let key = "HOME";
match env::var_os(key) {
Some(val) => println!("{key}: {val:?}"),
None => println!("{key} is not defined in the environment.")
}
If expecting a delimited variable (such as PATH
), split_paths
can be used to separate items.