Hello xanadol, and welcome to the Monastery!

Glad to see you found the solution. For the record, this is an FAQ: How do I change, delete, or insert a line in a file, or append to the beginning of a file?.

Some observations on your code:

• Great to see you useing strict and warnings!

• The while loop can be written more idiomatically:

print $fh $_ while <$fd>;
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• chomping $previous after the while loop does nothing.

If you want to prepend a line of text to an existing file in-place, you can use the core module Tie::File:

use strict;
use warnings;
use Tie::File;

my $file = $ARGV[0]                or die "$0 Usage:\n\t$0 <file>\n\n"
+;

tie my  @array, 'Tie::File', $file or die "Cannot tie file '$file': $!
+";
unshift @array, 'data';
untie   @array;
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Hope that helps,