I had to update several reverse zone files today, so wrote a quick for-loop in bash to freeze and thaw all the zones. The script parsed the zone file names and reversed them into a proper `d.c.b.a.in-addr.arpa` format. Later I tweaked it with sed to make it more flexible (in order to pass it a full or partial IP address), but ended up using `tac` for the reversing part instead – that’s what it’s made for after all. And if you’re wondering what `tac` stand for, just read `cat` backwards. :-)