Code is in: https://github.com/uutils/coreutils/blob/master/src/uu/who/src/who.rs Tests: https://github.com/uutils/coreutils/blob/master/tests/by-util/test_who.rs As example: https://github.com/uutils/coreutils/commit/9081e120d6b866c94679d9e29c7bdb17ccccb4d0