How would I add functionality to add a button that runs that exact command you just typed? By adding an 'add button' with a text field where you type your bash

How would I add functionality to add a button that runs that exact command you just typed? By adding an 'add button' with a text field where you type your bash script. All I have to do to make a GUI superior to your terminal is to add some GUI to an existing terminal that people find useful...