#!/usr/bin/perl -w
use Benchmark qw(:all) ;
use strict;

my $lsofcmd1 = "/usr/local/bin/lsof -c file_a|wc -l";
my $lsofcmd2 = "/usr/local/bin/lsof|grep file_a|wc -l";
my $lsofcmd3 = "/usr/local/bin/lsof";

my $count = "500";

my $results = timethese($count,
        {
            'lsof_c' => sub { system($lsofcmd1); },
            'lsof_grep' => sub { system($lsofcmd2); },
            'lsof_perl' => sub { my @ret = `$lsofcmd3`;
                                 print scalar(my @openfiles = grep(/file_a/,@ret));
                                },
        },
        'none'
    );
cmpthese( $results ) ;

##### Results ####
# Rate 	  	         lsof_perl   lsof_grep    lsof_c
# lsof_perl 13.4/s              --        -96%      -96%
# lsof_grep  321/s           2293%          --       -5%
# lsof_c     338/s           2422%          5%        --