cd
ls
In Linux the chmod command is used to set file permissions.
"rd" is a command which is "Remove directory" and the full form of the command would be "rmdir" depending on the OS used. It's commonly associated with UNIX or Linux based OS's.
The time command is used to time a command and not display the actual time. To display the time and date, the date command must be used.
Windows, MAC and Linux
In Unix, use the 'man' command.
vi
date
The ability to run a GUI is commonly called X11 with different implementations. The most popular in the Linux world is called X.Org Server. There are several but the most popular it seems are Gnome, KDE, and Xfce.
Linux home servers are not as common as other servers. One should note that Linux home servers are more likely to be used as a work station rather than a simple server.
The 'man' or the 'info' command have documentation about utilities and commands in the system.
$
NIS