String tests can be useful for checking user's input.
To check if two strings are equal or not, simply use the
$ [ 'hi' = 'hi' ]; echo $? 0 $ [ 'hello' = 'hi' ]; echo $? 1
Two unary operators are used to check if a string is empty or not.
$ [ -z "" ]; echo $? 0 $ [ -n "" ]; echo $? 1
Here's a simple script that reads an input, and depending on the string put in, returns a specific response.
#!/bin/bash printf 'Please enter a word: ' read input if [ $input = 'hi' ]; then printf 'Hi to you too!' else printf 'You input %s.\n' $input fi
We'll go over if-then-else statements soon, but notice how we can use tests and expressions such as these to control logic in our scripts.
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