We have a lot of code that uses Ethernet MAC addresses as identifiers. Sometime these are passed around nicely formatted as 
aa:bb:cc:dd:ee:ff

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where the letter pairs represent hexadecimally-encoded octets. Sometimes however a script will be passed a Cisco-style address: 
0001.0203.0405

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or even worse, something copied and pasted from a Windows dialog box: 
00-01-02-03-04-05

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The one-liner below converts incoming MAC addresses in (almost) any format into the desirable form, with octets separated by colons. The MAC to be filtered is in $_.

This could of course be cleaned up, using a qr// to avoid duplicating the hex-octet identifier. 

s/([0-9a-f]{2})[^0-9a-f]*/$1:/ig;chop;

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In reply to MAC Pretty-printer by moot

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