Mastering Linux Security and Hardening - Second Edition

Letting users run as other users

In the following line, (ALL) means that Sylvester can run the systemctl commands as any user:

sylvester ALL=(ALL) /usr/bin/systemctl status sshd, /usr/bin/systemctl restart sshd

This effectively gives Sylvester root privileges for these commands because the root user is definitely any user. You could, if desired, change that (ALL) to (root) in order to specify that Sylvester can only run these commands as the root user:

sylvester ALL=(root) /usr/bin/systemctl status sshd, /usr/bin/systemctl restart sshd 

Okay, there's probably not much point in that because nothing changes. Sylvester had root privileges for these systemctl commands before, and he still has them now. But there are more practical uses for this ...