Re: Bash scripting help...

Marko Vojinovic wrote:
I am writing a bash script to discover a MAC address of a remote host based on it's IP. Found that arping might be useful (is there a better method?), so I get

# arping -f -I eth0 $ipnumber
ARPING 10.0.0.3 from 10.0.0.1 eth0
Unicast reply from 10.0.0.3 [00:0C:29:C8:DE:E2] 1.040ms
Sent 1 probes (1 broadcast(s))
Received 1 response(s)

but the problem is that I just need to set the variable, say macaddr, to the above value, hopefully lowercase, without the [ and ]. Next obvious thing was:

# arping -f -I eth0 $ipnumber | grep Unicast
Unicast reply from 10.0.0.3 [00:0C:29:C8:DE:E2] 1.040ms

but I am over my head in extracting just the number. I guess awk is the tool, but the man page is not very illustrative and I do not have time/patience to learn to program in 'awk language' in order to do this thing. And C would probably be an overkill... :-)

Or this may work... (with the correct IP :/)

arping -f -I eth0 10.0.0.3 |\
grep Unicast |\
sed -e 's/.*\[\(..:..:..:..:..:..\)\].*/\1/'


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