pwck: Validate password files
Check and repair /etc/passwd and /etc/shadow entries to keep account data consistent and safe.
getent Query Name Services
Use one command to query passwd, hosts and other system databases through NSS.
Deny interactive logins with nologin
A quick way for the admin to block interactive shells while keeping service accounts intact.
Run commands as a different group
Use sg to execute a single command or a shell with another primary group to access group protected resources.
newgrp: switch your effective group
Run a shell under a different primary group so newly created files and commands inherit that group.
Switch Login Shells with chsh
Change a user's login shell from the command line quickly and safely.
