Question

I have this output from router command:

Interface              IP-Address      OK? Method Status                Protocol
POS0/0/0               10.137.99.2    YES NVRAM  up                    up    

I want to find a regular expression to identify the IP-Address:

I tried with:

if ( $_ =~ m/(.*?)\s*?(.*?)\s*?(.*?)\s*?(.*)/i ){
    #print "$1->$2\n";
    $sources{$2}=$1;
}

and then use $2 as ip.

However, it does not work; where am I wrong?

Answer 1

PacoRG’s answer works nicely, but to explain where yours is going wrong:

Remember that * can match no occurrences. You’re telling each group to match as little as possible, so the first 3 groups are capturing nothing. Further, you want to grab as many consecutive whitespace characters as possible, not as few.

Keeping with a RegEx somewhat like your original, you could use

m/(.+?)\s+(.+?)\s+(.+?)\s+(.+?)/i