login

login provides some required infrastructure for logins and for changing effective user or group IDs, including:

• login, the program that invokes a user shell on a virtual terminal;
• nologin, a dummy shell for disabled user accounts;
• su, a basic tool for executing commands as root or another user.

Reimplement this command in Rust:

• /bin/login
• /usr/bin/faillog
• /usr/bin/lastlog
• /usr/bin/newgrp
• /usr/sbin/nologin
• /usr/bin/sg

Upstream: https://github.com/shadow-maint/shadow