useful basic shell commands

clear : clear the terminal window, and put the cursor on top of the window

date: displays current date and time
dmesg: shows the kernel error messages

eject: eject a CD/DVD

exit: log out of a current user account being accessed at the command line(if issued within a terminal window) the window will close.

file: display useful information about the specified file
ex:- file myfile.txt

free: display information about the memory usage; add -m option to see o/p in megabytes
ex: show free RAM: free -m

halt: shut down the computer(needs to be run as the root)


help: shows a list of commonly used bash commands

last: show recent system logins

pwd: present working directory

reboot: reboot the computer(needs to be run as root)

shred: destroy the specified file beyond recovery by over writing it with junk data

touch: give the specified files date and time; if the specified file does n't exists
then create an empty file.the filename should be specified immediately afterwards

uptime: display how long the computer has been booted ,plus various cpu usage statistics

whatis: display a one-line summary of the specified command; the command name should follow immediately afterward

http://www.linuxcommand.org/