Shell scripting is essential for Unix users and system administrators-a way to quickly harness and customize the full power of any Unix system. With shell scripts, you can combine the fundamental Unix text and file processing commands crunch data and automate repetitive tasks. Writing shell scripts requires more than just knowledge about the language of shell, it also requires familiarity with the individual Unix programs: why each one is, how to use it themselves, and in combination with other programs. The authors are familiar with tips and tricks that can be used to create excellent scripts, as well as pitfalls that can make your best effort a bad shell script. The ability to program and customize the shell quickly, reliably, and portable to get the best from each individual system is an important skill for anyone operating and maintaining Unix or Linux systems.