Basic commands
List, copy, move/rename files/directories, remove files
$ ls -lh $ cp [destination] $ mv [destination] $ rm [file-name]
Get help, check available disk space, find a file in the current directory and all subdirectories, find out to what group [username] belongs
$ man [command] $ df $ find . -name testfile.txt $ groups [username]
Make and remove directories
$ mkdir [dir] $ rm -r [dir]
Make a symbolic link
$ ln -s [destination]
Add and remove users and groups
$ sudo adduser [options] username $ sudo usermod -aG sudo username $ sudo userdel -r username $ sudo groupdel Group_Name
Add user to group (The -G option refers to the groupname that follows).
$ sudo usermod -a -G {groupname} {username}
Remove a user from a group (Note: You have to specify the [groupname] in the command. Failure to do so will result in the removal of the user!).
$ sudo deluser [username] [groupname]
Reboot the server from the command line
$ sudo reboot