Essential Linux CLI Commands.

Essential commands for surviving at the Linux CLI

Moving around in the file system
Command	Action
pwd	"Print working directory" - show what dir you're in usually it shows absolute path.
ls	List the contents of a dir.
ls -l	List the contents of a dir and show additional info of the files.
ls -a	List all files, including hidden files.
cd	Change directory.
cd ..	Go to the parent directory.
Examining files
Command	Action
file	Determine the type of a file.
cat	Concatenate a file.
less	View text files and paginate them if needed.
Manipulating files and directories
Command	Action
cp	Copy a file.
cp -i	Copy a file and ask before overwriting.
cp -r	Copy a directory with its contents.
mv	Move or rename a file.
mv -i	Move or rename a file and ask before overwriting.
rm	Remove a file.
rm -r	Remove a directory with its contents.
rm -i	Ask before removing a file. Good to use with the -r option.
mkdir	Make a directory.
rmdir	Remove an empty directory.

Link http://www.tuxfiles.org/