Date: Tue, 26 Aug 2008 22:26:30 -0500 From: "Paul A. Procacci" <pprocacci@datapipe.com> To: Martin McCormick <martin@dc.cis.okstate.edu> Cc: freebsd-questions@freebsd.org Subject: Re: Regular Expression Trouble Message-ID: <48B4C966.9000602@datapipe.com> In-Reply-To: <200808270312.m7R3CJNk076060@dc.cis.okstate.edu> References: <200808270312.m7R3CJNk076060@dc.cis.okstate.edu>
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Martin McCormick wrote:
> 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
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>
I don't have a seperate dhcp log and you didn't make it clear if you do,
but I do have something similar written for awk that parses the system
log file.
awk ' /DHCPREQUEST/ { print $10 } ' /var/log/messages
Maybe that will help.
~Paul
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