All I wanted to do was take the 2 comma separated values and switch them around, per line

And you needed chop() or chomp() or more than one line of code to do it? Get with the program dude - you need discover inplace editing :-) The supplementary backup file is nice when your brilliant solution turns out to have just destroyed 10,000 zone records, not that I would know :o)

perl -pi.bak -e "s/([^,]+),([^,\n]+)/$2,$1/" data
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