Grab IP address from Received: header

[thehemi]

Quickest command to parse the IP address from a Received: header?
Surely there's a really obfuscated way to do this using sed, I bet.

For the uninitiated, the Received: syntax...

Received: from FQDN (FQDN [10.20.30.40]) by FQDN blah, blah...

(As some might imagine, I'm working on tweaking Procmail recipes.)

[anomie]

Going strictly on the info you've provided, you could use:

[mrbig ~]$ echo 'Received: from FQDN (FQDN [10.20.30.40]) by FQDN blah, blah...' | sed -e 's/.*\[//' -e 's/\].*//'
10.20.30.40

[ghostdog74]

awk  '/Received/{gsub(/\[|\]|\)/,"",$5);print $5}' file

[jozyba]

while read y; do z=${y%]*}; echo ${z#*[}; done <file

[thehemi]

Great info, thanks folks!