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Date: Tue, 26 Aug 2008 22:12:19 -0500
From: Martin McCormick <martin@dc.cis.okstate.edu>
Subject: Regular Expression Trouble
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I am trying to isolate only the MAC addresses that appear in
dhcpd logs.
For anyone who is interested, the sed construct that should do
this looks like:

 sed 's/.*\([[ your regular expression ]]\).*/\1/' 

The \1 tells sed to only print what matched and skip all the rest.

	I am doing something wrong with the regular expression
that is supposed to recognise a MAC address. MAC addresses look
like 5 pairs of hex digits followed by :'s and then a 6TH pair
to end the string.

	I have tried:

[[:xdigit:][:xdigit:][:punct:]

Sorry. It won't all fit on a line, but there should be a string
of 5 pairs and the : and then the 6TH pair followed by the
closing ] so the expression ends with ]]

One should also be able to put:

[[:xdigit:][:xdigit:][:punct:]]\{5,5\}[[:xdigit:][:xdigit]]

Any ideas as to what else I can try?

What happens is I get single characters per line that look like
the first or maybe the last character in that line, but
certainly nothing useful or nothing that remotely looks like a
MAC address.

	Any ideas as to what's wrong with the regular
expression?

	Many thanks.

Martin McCormick WB5AGZ  Stillwater, OK 
Systems Engineer
OSU Information Technology Department Telecommunications Services Group