Basic UNIX commands

Command	What for	Advanced version	What does it do?
ls	list contents of directory	ls -latr	list all files with more information, sort in reverse order than when it was created
cd	change directory	cd -	change to the last directory you were in
cp	copy files/directories	cp -a	copy while preserving all properties
mv	move file (change name)	mv -i	move but ask if you are overwriting an existing file
rm	remove (delete)	rm -rf *	delete everything, without asking and without mercy (very dangerous)
less	view an ASCII file