Why shouldn't it? The shell is arguably the most convenient way to interact with your system's programs, seconded only by something like Perl. That level of interaction ought to mean you can write functions such as for common tasks. Or should I now have to use Perl for that?
You can use functions outside of shell scripts - they can serve as a better kind of alias, or as a way of modifying the current shell without having to type the '.' before the script.
