The eval command allows you to run the contents of variables as commands and can be very useful -- especially in scripts.

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 ...

Unlike using environment variables in Linux, you can’t set them on the host and then pass those set variables to the container in the same way you would within the host system.

I'm storing sensitive info like the auth token in environment variables. The problem is, the python script can only see them when I run the script manually from the shell (so I know that the code ...

Another special variable that you might have encountered is the status variable, $?. In a script, this contains the return value of the most recently executed (external) command. This is where you ...