Function std::env::remove_var
1.0.0 · source · pub fn remove_var<K: AsRef<OsStr>>(key: K)
Expand description
Removes an environment variable from the environment of the currently running process.
§Safety
Even though this function is currently not marked as unsafe
, it needs to
be because invoking it can cause undefined behaviour. The function will be
marked unsafe
in a future version of Rust. This is tracked in
rust#27970.
This function is safe to call in a single-threaded program.
In multi-threaded programs, you must ensure that are no other threads
concurrently writing or reading(!) from the environment through functions
other than the ones in this module. You are responsible for figuring out
how to achieve this, but we strongly suggest not using set_var
or
remove_var
in multi-threaded programs at all.
Most C libraries, including libc itself do not advertise which functions
read from the environment. Even functions from the Rust standard library do
that, e.g. for DNS lookups from std::net::ToSocketAddrs
.
Discussion of this unsafety on Unix may be found in:
§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.
§Examples
use std::env;
let key = "KEY";
env::set_var(key, "VALUE");
assert_eq!(env::var(key), Ok("VALUE".to_string()));
env::remove_var(key);
assert!(env::var(key).is_err());
Run