In the real world, when you write code, you either maintain it forever or someone takes ownership of it later and makes changes into it. It is very important that you write a good quality shell script so that it's easier to maintain it further. It is also important that the shell script is bug-free in order to get the work done as expected. Scripts running on production systems are very critical because any error or wrong behavior of the script may cause minor or major damage. To solve such critical issues, it is important to get it fixed as soon as possible.

In this chapter, we will see how we can write modular and reusable code so that maintaining and updating our shell script application can be done quickly and without any hassle. We will also see how easily and quickly bugs in shell scripts can be solved using different debugging techniques. We will see how we can provide our users different choices for different tasks by providing support for command...