Importing external JS file in shell.js

Summary

Importing external JS file in shell.js

Content

Hi,
I tried to import and execute a custom JS file in shell.js using ajax call..
 $.getScript("../templateappn/resources/js/lib/jquery.main.js")
      .done(function(script, textStatus) {
        console.log(textStatus + "*********");
      })
      .fail(function(jqxhr, settings, exception) {
        $("div.log").text("Triggered ajaxError handler.");
      });
My Custom JS File is getting loaded and success msg is also getting printed in console.. but when it tries to read and execute the jquery functions present in custom js file.. it throws an error - "ReferenceError: $ is not defined" in the first line..

Not sure where to define the jquery symbol..