Introduction

This book is aimed at those UNIX users who find themselves looking after more shell scripts than they can comfortably shake a stick at. These will be System Administrators or Specialists looking after a legacy system or even a brand new development team that is subject to constant changes. The scope is indeed broad, as is the application of what is contained within this book. Be on the lookout at all times for opportunities to simplify. Always look for a generic solution, which will have wider application than the dedicated solution.

An understanding of UNIX will be helpful, but the reader need not have any shell programming experience. In fact to possess any existing bad shell scripting habits may hamper progress.

The conventions used in this book are very simple. The main text is in the same font and style as has been used here. Any examples of code will be presented as either one line or a numbered listing in Courier 8 point bold which looks like this:

Example code segment

# Example Code Example
echo "Hello World"
echo "The time is [`date +%h%m%s%p`] by my clock"

When required, screen output will use the same font as code but in a regular type instead of bold which looks like this:

Example screen output

user@system$   my_script   argument
Hello World
The date is [12:37:42pm] by my clock

UNIX Command words, like ls or cp will be picked out in the text as bold, while variables used within the text body will be in italic text. Examples of UNIX command lines will be printed in Arial 10 point bold text which looks like this:

Example Command Line

cat *.log | sort -u > filename

And finally a Health Warning for Real Programmers: Real programmers may get upset by some of the constructs used here. I make no apologies to the incensed reader. Just remember, there are no correct ways in shell programming, just ways that work. I hope you have as much fun trying out the concepts used in this book as I had while writing it.