After you've opened *IN from the input file and *OUT to the output, use the $. variable to tell you how many lines have been read. 

while (<IN>) {
    print OUT $_ if 1 & $. ;
}

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which will print odd-numbered lines to OUT. Replace if with unless to print even lines.

Update: Corrected typo.

After Compline,
Zaxo

In reply to Re: How to Print Every Other Line by Zaxo
in thread How to Print Every Other Line by Neuroactive

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