16.1. Introduction

System administrators are in charge of tasks that require expertise beyond the user level, such as modifying boot scripts, adding users, fixing installation software, monitoring processes, mounting filesystems, backups, and much more. Because many of the system tasks have been automated with shell scripts, the system administrator requires knowledge of shell programming so that he or she can read and modify existing scripts, and create new scripts when the need arises. This chapter is not meant to be a definitive guide to system administration, but rather a look at system administration in respect to the UNIX/Linux shell. It will cover topics such as running shell scripts as root, system boot scripts, shell initialization scripts, and how to write portable shell scripts. Examples will be provided from specific UNIX/Linux versions that will run on a majority of systems. You will need to consult the documentation for your specific release for more specific information.

If you are familiar with system administration, you may find that the information in this chapter fills a gap in your knowledge. If you are new to system administration, you will gain an understanding of shell topics often not used by unprivileged users.