match IP address

Question

by the following grep syntax I want to match all IP address in file (from ksh script)

  grep '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}' file

the problem: its match also words(IP) that have more then 4 octet :

1.1.1.1.1 

or 192.1.1.1.160

my question

how to match VALID IP and only IP address with only 4 octets

remark: I can accept also perl - one line syntax solution (if grep dont help us)

Answer 1

try this:

grep -E '[1-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' /etc/hosts

which matches all expressions from 1.0.0.0 to 999.999.999.999

with

grep -Eo '[1-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' /etc/hosts

you will get IP addresses only

note:
on solaris probably egrep will do the job.

Answer 2

How's this:

perl -MRegexp::Common=net -ne '/($RE{net}{IPv4})/ and print "$1\n"' /etc/hosts

Answer 3

A little tricky, but it should work:

( X='\([0-9]\{1,2\}\|1[0-9]\{2\}\|2[0-4][0-9]\|25[0-5]\)' ; grep "\([^\.]\|^\)$X\.$X\.$X\.$X\([^\.]\|$\)" file )

Answer 4

Well, this depends on whats the file like, maybe you can add an end of line anchor or a whitespace class. But overall this don't seem to be an easy question.