Here are some Linux shell commands that you might find useful on a day to day basis. You can also view the man pages of these commands to learn more.

clear : Clear the terminal window.

date : Display current date and time.

dmesg : Show output of the kernel, including error messages.

eject : Eject CD/DVD.

exit : log out of the current shell (if issued in a terminal window, the window will close).

file : Display useful information about the specified file. (eg. file myfile.txt)

free : Display information about memory usage.

halt : Shutdown the computer. (Needs to run as root.)

help : show a list of commonly used BASH commands.

last : Show recent system logins.

pwd : Print Working Directory; This will simply show the full path of where you are currently working.

reboot : Reboot the computer (Needs to be run as root.)

shred : destro the specified file beyond recovery by overwriting junk data.

touch : give the specified files current date and time; if file does not exists, then it will create an empty file.

uptime : Display how long the computer has been booted and various CPU usage.

whatis : Display a one-line summary of the specified command.