Function std::env::var_os1.0.0[][src]

pub fn var_os<K: AsRef<OsStr>>(key: K) -> Option<OsString>

Fetches the environment variable key from the current process, returning None if the variable isn’t set.


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.


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)