CH's Introduction to GIS the UNIX Way

Introduction to Unix

Unix has been implemented on a wider range of machines than any other operating system. There are two popular versions: AT&T's Unix and Berkeley System Division(BSD). BSD was developed at University of California at Berkeley as an enhanced version of AT&T's Unix. It was develped out of a need for better utilities in programming and networking. Many of these "Berkeley enhancements " have been implemented into the latest release of AT&T's Unix. AT&T's lastest release is called SystemV or System 5 and BSD is on release 4.4. Because of licensing problems many vendors choose to write their own versions of Unix. For instance, Hewlett Packards Unix operating system or HP-UX is based on both SystemV and BSD.

Unix has many important and powerful features. Perhaps the three that have contributed most to its success are multi-tasking, multi-user, and built in networking.

Unix is a multi-tasking operating system. A user can perform more than one task at a time. These tasks or processes can be run in the background so that the user can continue with other activities. For example, a user could be sorting a file or making a calculation in the background at the same time they are editing a file.

Unix is a multi-user operating system. Many users can be using the same machine. This is directly related to multi-tasking since each user just has their own set of processes. The multi-user aspect allows groups of people to work easily together, sharing files and utilities.

Unix networking is built into the operating system. A diverse and powerfull set of networking tools have developed over the lifetime of Unix. Today some of these tools are becoming standards in non-Unix environments.