sub daemonize {
    require POSIX;
    my $logfile = shift;
    $logfile = '/dev/null' unless defined $logfile;
    chdir '/' or die "Can't chdir to /: $!";
    open STDIN, '/dev/null' or die "failed opening STDIN: $!";
    open STDOUT, ">>$logfile" or die "failed opening logfile $logfile: $!";
    {
        defined(my $pid = fork) or die "Can't fork: $!";
        exit if $pid;
    }
    POSIX::setsid() or die "Can't start a new session: $!";
    open STDERR, '>&STDOUT' or die "Can't dup STDOUT for STDERR: $!";
    return 1;
}