#!/usr/local/bin/perl 
open INFILE, "$ARGV[0]";
@file = <INFILE>;
close INFILE;
$_ = shift @file;
/^#!/ or die "no shebang, file left untouched";
/-d/ and die "file already in debug mode";
s/$/ -d/;
open OUTFILE, ">@ARGV[0]";
print OUTFILE $_;
for (@file) { print OUTFILE $_ }
close OUTFILE;