instead of using the shell to set up the redirections do it yourself from perl:

sub my_system {
  my @cmd = @_;
  my $pid = fork;
  defined $pid
    or die "couldn't fork";
  if (!$pid) {
    open STDOUT, '>>&', \*LOGFILE
      or exit(1);
    open STDERR, '>>&', \*LOGFILE
      or exit(1);
    exec @cmd1;
    exit(1);
  }
  waitpid($pid, 0);
  return $? == 0;
}

my $status1 = my_system($cmd1, @args1);
my $status2 = my_system($cmd2, @args2);
[download]