I don't think I would like that too much. Now I quite often use the fact
that you can do something like:
$foo =~ /$input/;
where whatever the user types, he can't damage the integrity of your program.
With that proposed extension he would be able to execute anything he wants.
I would at least want a letter I could put after the // to forbid (?e )
Not a bad thing to bring up - how many cgi scripts out there implement
an equivalent thing?