Curious, which license can't you use at work for a simple shell tool? Considering you're not linking against it, even GPL3 should be okay, right?

Most big employers consider GPL unusable and will only allow Apache, MIT, BSD, and other permissive patent-free licenses.

So they don't let you use grep? Sounds like hell.

Yeah, caution with GPL is understandable if you're shipping it or making it a part of a hosted service. But internal use is not the intention of GPL, so a blanket ban like that would put that shop at a disadvantage, like the other comment said, that basically rules out all kinds of things.