Since you're running on Unix and not Win32, this solution will work for you.

What you want to do is to select on STDIN every so often. Say, every time a certain loop starts over or every section or whatever. The code you're looking for is:

# Whenever you want to actually see if there's something waiting
my $rin = '';
my $input = '';
vec($rin, fileno(STDIN), 1) = 1;
$input = <STDIN> if select($rin, undef, undef, 0.1);
[download]

That should work. It's best if you write a subroutine and return either undef (if nothing) or what was read. You can even chomp in the subroutine, as well.

Oh - you'll have to hit RETURN so that the filesystem can pass in the values. There's no native keypressed-type thing. (You can get it with Term::ReadLine and the like, but that's more complex than I think you want.)

And, this will not work under Win32 without significant changes, due to how select is implemented there. Unless you're planning on migrating, don't worry about it. :)

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/me wants to be the brightest bulb in the chandelier!