-sudo + command: to execute a command with super user rights.
-shutdown -h now: shutdown the machine, with the halt option, -r to restart
-apt-get update: update the list of package available in the repository
-apt-get upgrade: upgrade packages on your machine
-uname -a: give info of the machine with the all option
-history: Histoy of the command used
-clear: clear the terminal
-exit: exit from the terminal

sudo apt-get install tree
tree /home -La 2

setxkbmap fr: set the keyboard in azerty
setxkbmap en: set the keyboard in qwerty