package MyPack;
use strict;
use warnings;
use Posix ":sys_wait_h";
use constant STATUS_STOPPED=>'stopped';
use constant STATUS_RUNNING=>'running';

$SIG{CHLD}=\&reap_child;

sub new{
 my $class=shift;
 my $self= bless{
  _pid=>undef
  , _status=>STATUS_STOPPED 
  }, $class;
  return $self;
 }

 sub run{
    my $self=shift;
    my $command=shift;
    croak "Process: no comand ist given \n" unless $command;
    my $child= fork();
    die "Process: Forking error $? \n" unless defined  $child;
    if($child>0){
      $self->{_pid}=$child;
      $self->{_status}=STATUS_RUNNING;
    }
    else {
         exec($command);
    }
 }

 sub reap_child{
    if (waitpid($self->{_pid},WNOHANG) > 0) {
        $self->{_status}=STATUS_STOPPED;
        $self->{_pid}=undef;
    }
  }