Why are you using cat? Wouldn't

    $line_count = `wc -l $filename`
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work just as well?

Of course one could argue that you could just do the entire thing in Perl rather than using system calls; I might argue that, for instance. Here's a version of wc in Perl; you could extract the bits you need.

Or you could do something like this:

    sub lines_in_file {
        my $f = shift;
        open FH, $f or die "Can't open $f: $!";
        1 while <FH>;
        $.;
    }
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This would take care of your "space-in-filename" problem as well, since Perl won't care; it's only a problem when you pass it off to the shell like that.

You can use this like:

    my $line_count = lines_in_file($filename);
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