Linux Commands

The Research Computing HPC server’s use Red Hat Enterprise Linux (RHEL) as the operating system. Many clusters around the world run exclusively Unix/Linux based operating systems. We strongly encourage users to actively get familiar with Unix command line interface and GNU/Linux in particular. Outstanding and Free documentation is provided at The Linux Documentation Project, specifically their Guides which cover basic topics including Using Linux and shell scripting to advanced File system and kernel modulization guides. Below is a succinct list of Unix commands that will help you get started in moving around and manipulating files.

Moving around the file system

pwd	List current directory
ls	List contents of current directory
ls -l	List contents of current directory with more information per file including permissions, last edited time, and size of file
ls -lh	Same as ls -lh except file size in included in ‘human readable’ form (gigabytes, megabytes, kilobytes)
ls -lt	Same as ls -l, except list files in chronological order with newer files occurring at the top
cd *dirname*	Changes current directory to dirname
cd ..	Changes current directory up one hiearchy level

Examining Files

cat *filename*	Concatenates filename and prints to standard output (screen)
less *filename*	A filter that pages through filename one screenful at a time. Allows both forward and backward movement through file
more *filename*	Similar to less, except cannot move backwards through file

Manipulating Files and Directories

cp *filename1 filename2*	Copies filename1 to filename2. If filename2 is the name of a directory, copies filename1 into the directory
cp -i *filename1 filename2*	Copies filename1 to filename2 and ask permission before overwriting
cp -r *directory1 directory2*	Copies ‘’directory1 and all of it’s contents to directory2
mv *filename1 filename2*	Renames filename1 to filename2. If filename2 is a directory, moves filename1 into directory
mv -i *filename1 filename2*	Renames filename1 to filename2 and ask permission before overwriting files
rm *filename*	Removes file
rm -i *filename*	Removes file and ask permission before doing so
rm -r *directory*	Removes directory and it’s contents
rm -ir *directory*	Removes directory and it’s contents asking permission for each file
mkdir *directory*	Create a directory with directory as a name
rmdir *directory*	Remove an emptry directory