#!/usr/bin/perl
use warnings;
use strict;
use IPC::Open3;
use IO::Select;

my $pid = $$;

my $pid1 = open3(0, \*READ,\*ERROR,"top -d 1 -b -p $pid ");
#if \*ERROR is false, STDERR is sent to STDOUT 

my $sel = new IO::Select();

$sel->add(\*READ);
$sel->add(\*ERROR);

while(1){

foreach my $h ($sel->can_read){
    my $buf = '';
        if ($h eq \*ERROR){
              sysread(ERROR,$buf,4096);
              if($buf){print "ERROR-> $buf\n"}
}else{

 sysread(READ,$buf,4096);
    if($buf){print "$buf\n"}
   }
  }
}