Testing variables There are quite a few ways to test the values of variables, but the operators you need to use depend on whether you’re comparing numbers or strings.

A lot of important values are stored on Linux systems in what we call “variables,” but there are actually several types of variables and some interesting commands that can help you work with ...

In a previous column, I showed how to do substring expansion with shell variables in the form of $ {var:start:length}, but it's also useful to know the length of a variable's value. This can be done ...