Chapter 3. Conditions Attached

 

Now you can make your scripts more interactive using the read command, and you know how to read parameters and options to lighten your inputs.

We can say that we are now into the fine print of the script. These are the details that are written into our scripts using conditions to test if a statement should run or not. We are now ready to add some intelligence into our scripts, so our scripts become more robust, easier to use, and more reliable. Conditional statements can be written with simple command-line lists of AND or OR commands together, or, more often, within traditional if statements.

In this chapter, we will cover the following topics:

• Simple decision paths using command-line lists
• Verifying user input with lists
• Using the test shell built-in
• Creating conditional statements using if
• Extending if with else
• Using the test command with the if command
• More conditions with elif
• Using case statements
• Recipe-frontend with grep