diff: 

system(diff => (
    "--unchanged-line-format== %5dn %l\n",
    "--old-line-format=- %5dn %l\n",
    "--new-line-format=+ %5dn %l\n",
    $old_file,
    $new_file,
));

[download]
or Algorithm::Diff

In reply to Re: Printing Line Numbers in output file by ikegami
in thread Printing Line Numbers in output file by Anonymous Monk

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