Can't find how to put the command line on the toolbar

Had it once. Lost it when reinstalling. Can't find it again. Help file wasn't.

You're probably after this:

Although, these days, you can save the toolbar space and just type ">" into the lister whenever you need to execute a command (or "?" if you want to run it in a DOS window), which will cause this to appear:

Wow, thanks so much for this! Yet another thing about Opus I didn't know.