How to insert a text field, a button on the page in wordpress and process the text on button click?

Question

CMS

Give an example, let's say how to make a text field and a button on the main page of WP, and when the button is pressed, execute a command on the local machine, for example, ls -al $TXT_FIELD. And explain in which file this should be done so that there are no ugly crutches. The goal is to make several text fields, when filled with information, when a button was pressed, a query (Linux command) was executed on the local machine.