Chapter 8. Automating Decision-Making in Scripts

In the last chapter, you learned about performing arithmetic operations in various ways, such as using declare, let, expr, and arithmetic expressions. You also learned about representing numbers in different bases, such as hex, octal, and binary, and using the bc utility for performing floating point or fractional arithmetic.

In real-world scripts, it is not just a sequential execution of commands, we need to check certain conditions or proceed according to certain logic, and then the script should continue executing. This is precisely what we do with automation. Automation refers to performing tasks, the sequence of which will change according to changes in the programming environment. A simple example would be to check whether a directory is present; if present, then change to that directory. Otherwise create a new directory and proceed. All these activities come under decision-making in shell scripts.

In this chapter, we will cover the following...