the command chmod changes the mode of a file.

the command su switches the current user to another.

the command sudo allows for execution of commands as a different user such as a superuser.

the command chown changes the owner of a file.

the command passwd changes user passwords but normal users can only change their own.

the command ps takes a snapshot of the current running programs and displays the PID’s.

kill command

The command kill, kills a process identified by its PID.

the command printenv displays the current environmental factors.