If you want to do this all in Perl, rather than resorting to system calls, try Proc::ProcessTable - it should give you the state of a process, and lots of other rather useful bits of information you'd expect from UNIX commands like top and ps.

Here's a quick and dirty example to print the PID, state and commandline of all of the processes that are on CPU when the script runs (tested on Linux - IIRC on Solaris you should look for the phrase "On processor"):

#!/usr/bin/perl

use strict;
use warnings;

use Proc::ProcessTable;

my $t = new Proc::ProcessTable;

foreach my $proc (@{$t->table}) {
  if ($proc->state =~ /run/oi) {
    print join " ",
          $proc->pid,
          $proc->state,
          $proc->cmndline,
          "\n";
  }
}
[download]

Cheers

BazB

Update: BTW, there are a number of methods that Proc::ProcessTable offers that will give you the amount of CPU time used by a process (and it's children if you want) and the like. Check the module's README.