Now that you’ve seen how to use the different ways to create loops in shell scripts, let’s look at some practical examples of how to use them. Looping is a common way to iterate through data on the system, whether it’s files in folders or data...

You might be tempted to think that after you start a loop, you’re stuck until the loop finishes all its iterations. This is not true. A couple of commands help us control what happens inside of a loop: The break command The continue command Each command...

The until command works in exactly the opposite way from the while command. The until command requires that you specify a test command that normally produces a nonzero exit status. As long as the exit status of the test command is non-zero, the bash shell executes...

Iterating through a series of commands is a common programming practice. Often, you need to repeat a set of commands until a specific condition has been met, such as processing all the files in a directory, all the users on a system, or all the lines...

Often, you’ll find yourself trying to evaluate a variable’s value, looking for a specific value within a set of possible values. In this scenario, you end up having to write a lengthy if-then-else statement, like this:

So far, all you’ve seen in the if statement line are normal shell commands. You might be wondering if the bash if-then statement has the ability to evaluate any condition other than a command’s exit status code. The answer is no, it can’t. However, there’s a...

In the if-then statement, you have only one option for whether a command is successful. If the command returns a non-zero exit status code, the bash shell just moves on to the next command in the script. In this situation, it would be nice to be...

The most basic type of structured command is the if-then statement. The if-then statement has the following format: Syntax if command then commands fi