BrowserUK already pointed out your particular problem with backticks. One thing I would suggest is you can use characters other than '/' for matching and substitution, etc. I'm a big fan of doing this when it makes things easier to follow. Anytime '/' or '\' is involved is a good time for {} or other characters.

##########################################################
#                        change back slashes to forward
sub slashfwd { 
    my $retval = $_[0];
    $retval =~  s{\\} {/}g;
    return $retval;
}
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