ls : Displays list of files in the present working directory.

cd directory : Changes directories .

passwd : Changes the password of current user .

file filename : Displays file type of file with name filename .

cat textfile : Throws content of text file on the screen

pwd : Shows present working directory

exit or logout : Leaves the session

man command : Read about command on man pages.

info command : Read about command on info pages.

apropos string : For searching database for strings