in reply to qx and $!

From perldoc perlvar:

...if a system or library call fails, it sets this variable. This means that the value of $! is meaningful only immediately after a failure

As there was no failure, the value of $! is meaningless in your example.

--
<http://dave.org.uk>

"The first rule of Perl club is you do not talk about Perl club."
-- Chip Salzenberg