====== MANAGING USERS ======

==== CHANGING IDENTITIES ====

There are two option to take on the identity of another user:
  * **su** - start the shell as another user or issue a single command as that user
  * **sudo** - allows a user to execute commands as a different user (usually the root). Config file //etc/sudoers// defines specific commands that particular users can execute under an assumed identity

==== SU ====

Start shell as a root:
<code bash>
victor@rasp-4:~ $ su -
Password:

root@rasp-4:~#
root@rasp-4:~# su -l victor

victor@rasp-4:~ $
</code>
==== SUDO ====

The difference from **su**:
  * The user might be restricted to one or more commands
  * sudo does not require an access to superuser's password
  * sudo doesn't start a new shell

Running any command as //root// without having to enter a password:
  * **sudo visudo** - modifies /etc/sudoers/
  * Add file to ///etc/sudoers.d//

Example config for user //victor// (/etc/sudoers.d/010-victor-nopasswd):
<code>
victor ALL=(ALL) NOPASSWD: ALL
</code>

Which means:
  * ALL=(ALL) - victor can run commands for any user on any machine
  * NOPASSWD: ALL - no password needed for any command
==== GROUPS ====

Adding a user to the group:
<code bash>
# usermod -aG sudo victor # 'a' - append; 'G' - group
</code>