Bash: How to Check if String is Not Empty

You may not have experienced it, but it does happen.

One of these days, you may experience it. Sometimes, a bash script may contain empty variables. Here, we have provided every detail on how to check for empty variables in a bash script, as well as introduce a handy freeware for managing Linux partitions on Windows PC.

Here you will find out:

• bash command if a string is not empty

• examples of the check

• when DiskInternals can help you

Are you ready? Let's read!

-n operator

-n is one of the supported bash string comparison operators used for checking null strings in a bash script. When -n operator is used, it returns true for every case, but that’s if the string contains characters. On the other hand, if the string is empty, it won’t return true.

-z operator

-z is the second supported bash string comparison operator used to check if a string is empty or not. The -z operator functions similarly like -n operator. Below is an example:

Most importantly, you should add spaces around the square brackets. If there are no spaces, bash will complain about that. Also, since any bash test without an argument will always return true, it is advisable to quote the variables so that the test will have at least an (empty) argument, irrespective of whether the variable is set or not.

Check to see if a variable is empty or not

Create a new bash file, named, and enter the script below.

The script above stores the first command-line argument in a variable and then tests the argument in the next statement.

This script will print the first argument because it is not empty. However, the output would be “First argument is empty” if nothing is contained in the argument.