Question

In linux:

Perl scripts

What would be the search pattern for extracting all the lines that contain at least a 3-digit number in /etc/services, such as the lines that have 110 (pop3) or 143 (imap), but not the lines that contain 1649 (kermit), 3306 (mysql), or 10080 (amanda), etc.

Answer 1

#!/usr/bin/perl

use strict;

my $filename = '/etc/services';

# opening file to read

open my $info, $filename or die "Could not open $filename: $!";

# reading line by line

while( my $line = <$info>)  {   

    if ($line =~ /#/){}

    else{

    # splitting by space to find 2nd col

    my $v =  ((split ' ', $line)[1]);  

    # splitting by / to find process id

    my $proceess_id = ((split '/', $v)[0]);

    # if length 3 then printing it

    if (length($proceess_id)==3){

        print $line;

    }

    }

}

# OUT