Usually, one of the first things a Linux/Unix user learns is to create a shell script. The process generally goes like this:

1. Write a script.sh file.
2. Fill it with

   #!/bin/bash
   echo "Hello world"
   

3. Make it executable with chmod +x script.sh
4. And finally, run it with ./script.sh

Nice and simple, and most *nix users are familiar with this. For an average user, the journey ends right then and there, but if you’re interested, you realize that there’s always ways to use and abuse the tooling.