Ask HN: What are some good examples to demonstrate unix philosophy?

If you were to explain to someone how linux is different, how simple tools are used together to achieve just about anything, what example(s) would you give them? I'm talking about a shell pipeline that's useful and easy to understand but one that would be very difficult to get done in an environment like windows. Examples other than a shell pipeline are also fine as long as an outsider can relate to them.

I use gnu parallel a lot and naturally that's my first choice, something like:

$ <urllist ssh user@host 'parallel -j 30 curl "{}" | grep -Po "tel:\d+" | sed "s/tel://" | sort -u'