LIS 525 - Unix and Linux

Unix is an operating system used on many mainframe computers, including There are also distributions suitable for smaller computers, such as FreeBSD. A version of Unix forms the basis of Apple's Mac OS X.

Linux looks very similar to Unix to the user and recognizes most of the same commands. Linux image courtesy of Larry Ewing ( 
created with The GIMP software Linux is free and is distributed under the GNU General Public License. It was originally created by Linus Torvalds and is being developed with the assistance of people around the world. A number of companies (e.g., Debian, Red Hat, Slackware) have developed their own distributions of Linux, each with its own feature set, some available at no charge via FTP, and others purchasable on CD, or as a companion to a Linux book. Some computer suppliers sell workstations with Linux preinstalled.

Note that all commands, file names, and passwords in Unix and Linux are case sensitive (in OS X, file names may or may not be, depending on configuration).

Directory Structure

The root directory is / (forward slash, not \ as in DOS or Windows). Each user's files are typically in a subdirectory with the same name as the user's login name. Some confusion can be created, however, because Unix/Linux files also have "owners", who may not be the same as the owner of the directory in which the files appear. When users log in, they are normally automatically put initially in their own directories.

A single period (.) represents the current directory in commands and .. represents the directory immediately above in the hierarchy.

Some Commands

For More Information


Last updated October 31, 2007.
This page maintained by Prof. Tim Craven
E-mail (text/plain only):
Faculty of Information and Media Studies
University of Western Ontario,
London, Ontario
Canada, N6A 5B7