Regex Question: Only print part of line that matches

TheMeteorPolice · 01-10-2006, 12:45 PM

Greetings,

Overview: I need to be able to use a regular expression to display only parts of a line that match the expression.

Input: A file that is filled with error messages from different hosts. Each line has an error message and the IP address that caused the error.

Desired Output: A list of all the IP addresses found in the file.

Here is what I have currently. It returns the proper lines, but I only want to print the part of the line that matches, so I end up with a list of IP addresses only. The IP address could be located anywhere in the line so I cant use something like awk to just print the proper field - it will be different for each returned line.

Code:

egrep '\([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+\)'

Thanks in advance guys

puffinman · 01-10-2006, 01:20 PM

Here is a perl script I wrote a while back. It actually prints the ips and how many times they appear, but you should be able to alter it to suit your needs. You can put your input file(s) as an argument or feed whatever input to stdin.

Code:

#!/usr/bin/perl

use warnings;
use strict;
use Getopt::Long;


my $thresh = 0;
my $comma;
my %ips;

GetOptions(
           "threshold=i" => \$thresh,
           "comma" => \$comma,
           ) or die "Options problem";

while (<>) {
      if (m[((\d{1,3}\.){3}\d{1,3})]) {
        $ips{$1}++;
      }
}

foreach my $ip (keys %ips) {
    next unless $ips{$ip} > $thresh;
    if ($comma) {
        print ",$ip";
    } else {
        printf "%-18s - %5d\n", $ip,$ips{$ip};
    }
}

schneidz · 01-10-2006, 03:48 PM

Quote:

Originally Posted by TheMeteorPolice

Greetings,

Overview: I need to be able to use a regular expression to display only parts of a line that match the expression.

...

Thanks in advance guys

the grep manpage says option -o only prints the part matched by pattern.

TheMeteorPolice · 01-11-2006, 12:41 PM

Ah yes you are correct. I was working on a Solaris box that did not have the -o option, but after moving the data to my Fedora workstation I have it.

Thanks!!

bigearsbilly · 01-12-2006, 04:52 AM

Quote:

I was working on a Solaris box that did not have the -o option,

I had exactly the same problem

I ended up with this:

Code:

#!/usr/bin/perl -wn


print "$ARGV:$&\n" while  ( m/YOUR_PATTERN_HERE/g ) ;

works nicely

schneidz · 01-12-2006, 01:21 PM

i have problems like this all the time between aix(work) and linux(home).

very annoying to say the least.