Intro

Linux, like UNIX, is a multi-tasking and a multi-user system. This means that the system can run multiple programs at the same time, and it can be used by more than one user at the same time. One of the challenges of such a system is that it needs to identify users and protect them from each-other.

• Users and groups, permissions:
  useradd, passwd, id, chmod, umask, su, sudo, chown, chgrp

• Processes and signals:
  ps, pstree, top, jobs, bg, fg, kill, killall, shutdown

informazioni

The commands in the first and second parts need to be given as user root. Usually you can switch to this user with the command:

sudo su

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