If it is not true then don't perform those actions.

Basic If StatementsĪ basic if statement effectively says, if a particular test is true, then perform a given set of actions. Like what we have looked at in previous sections, their syntax is very specific so stay on top of all the little details. If statements, combined with loops (which we'll look at in the next section) allow us to make much more complex scripts which may solve larger tasks. They allow us to decide whether or not to run a piece of code based upon conditions that we may set. If statements (and, closely related, case statements) allow us to make decisions in our Bash scripts. In this section of our Bash Scripting Tutorial you will learn the ways you may use if statements in your Bash scripts to help automate tasks. Because it's within a subshell, if you have it inside a loop, it will run a little slower than if you called the commands without the parentheses.Bash if statements are very useful. Any variables declared or environment changes will get cleaned up and disappeared. This means that they run through all of the commands inside, and then return a single exit code. Single parenthesis will run the commands inside in a subshell. We'll go through in order of net total squigglyness (NTS score). It doesn't like space where curly braces are concerned. So here we go.Ī tiny note on all of these is that Bash generally likes to see a space between round or square brackets and whatever's inside. So here, I'm going to lay them all out and then print this article out and staple it to the wall by my desk. I constantly find myself doing a 5-second search for which one is the right one to do since I'm not writing Bash scripts all the time. And, the brackets are used differently than many other languages. It adds meaning to doubling up different brackets, and a dollar sign in front means something even more different. Bash has lots of different kinds of brackets.

Brackets ubuntu