Function std::env::var_os 1.0.0[−][src]
pub fn var_os<K: AsRef<OsStr>>(key: K) -> Option<OsString>
Expand description
Fetches the environment variable key
from the current process, returning
None
if the variable isn’t set.
Panics
This function may panic if key
is empty, contains an ASCII equals sign
'='
or the NUL character '\0'
, or when the value contains the NUL
character.
Note that the method 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!("{} is not defined in the environment.", key) }Run