All right, let's look. Command Overview.
Now, the funny thing is that the Command Overview is relatively short this time,
because we talked about shell features a lot, which are not executed as command.
But we have seen the T command, which allows you to send output in
two directions to a file and to be further processed in a pipe.
We've seen History, which allows you to work with your command line history, Alias, which
allows you to define your own commands, and export, which is what you want to
use while setting variables in a way that they are available in subshells as well.