my $pid = open(my $FROM_KID, "-|");
die("Failed fork: $!") unless defined($pid);

if ($pid) # parent
{
    chomp(my $output = do { local $/; <$FROM_KID> });
    waitpid($pid, 0);

    printf <<'RESULT', $output, $? >> 8;
Child output: %s
Exit: %d
RESULT
}
else
{
    daemonize_self("", undef); # leave stdout alone
    exec "date" or die("Failed exec: $!");
}

##</code><code>##

use Cwd ();
use POSIX ();
use File::Spec;

sub daemonize_self {
    my ($stdout_log, $stderr_log) = @_;

    # new session & process group leader, and no controlling tty
    die("daemonize_self: Cannot detach from controlling tty")
      if POSIX::setsid() < 0;

    # ignore signals
    for my $s (qw(INT HUP TTIN TTOU TSTP))
    {
        $SIG{$s} = sub { }; # not "IGNORE", not inherited
    }
    $SIG{CHLD} = "IGNORE"; # inherited default to reap kids
    $SIG{TERM} = "DEFAULT";

    # be lenient: redirect stdin, stdout, stderr
    my $DEVNULL = File::Spec->devnull();

    open(*STDIN, "<",  $DEVNULL)
      or die("daemonize_self: Cannot silence STDIN", "\n  ", $!);

    unless (defined($stdout_log) && $stdout_log eq "")
    {
        open(*STDOUT, ">>", defined($stdout_log) ? $stdout_log : $DEVNULL)
          or die("daemonize_self: Cannot redirect STDOUT", "\n  ", $!);
    }
    unless (defined($stderr_log) && $stderr_log eq "")
    {
        open(*STDERR, ">>", defined($stderr_log) ? $stderr_log : $DEVNULL)
          or die("daemonize_self: Cannot redirect STDERR", "\n  ", $!);
    }

    # close all other file descriptors
    POSIX::close($_) for 3 .. 1024;

    # reset file creation mask
    umask 0;

    # change current working dir to root
    chdir(File::Spec->rootdir());
}