Inline debugging is really, really helpful in cases like this. You might also want to change the 

print OUT $_;

[download]
to 
print ;

[download]
to print your lines on the screen.

And for a sanity check, you might put something like: 

print "\$in_file: $in_file \n";
print "\$out_file: $out_file \n";
print "\$pattern : $pattern\n";
print "\$replacement:  $replacement\n";

[download]
before your open commands. Just to make sure you're opening the file(s) you think you're opening.

In reply to Re^3: Not A Rockstar File Manipulator Today by mpeever
in thread Not A Rockstar File Manipulator Today by koolgirl

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