my $pid = open(CHILD, "-|", 'child', @child_args)
if ($pid) {
  while (<CHILD>) { $logger->($_) }
}
close(CHILD);

##</code><code>##

if (my $pid = open(CHILD, "-|")) {
  while (<CHILD>) { $logger->($_); }
  close(CHILD);
} else {
  open(STDERR, '>&STDOUT');
  exec('child', @child_args) || die "exec failed";
}