The 'man' or the 'info' command have documentation about utilities and commands in the system.
In Linux the chmod command is used to set file permissions.
In Linux the man command displays the help(man page) for a command. man fdisk is "display the man page for command fdisk"
vi
date
$
NIS
cd ls
In the context of the Linux command 'mv r', the keyword 'mv' stands for 'move', indicating that the command is used to move or rename files or directories.
The TAR command is Create Tape ARchives and is used by Linux and Unix. Information and explanations can be found on the linfo and computerhope websites.
Use the 'newgrp' command.
su command is used to change the user.
''ipconfig/all''