## Exercise 4

The final exercise for today is to chain a few commands into a single pipeline
that takes all the text files in today's tutorial and lists all the command
names (programs) that appear in the examples, one per line. Each command
should appear exactly once. For instance, ‹fgrep›, ‹echo› or ‹less› should be
listed (among quite a few others).

That's all. The homework is described in ‹hw.txt›. Good luck and have fun.
