sub background {
    my $self  = shift;
    my $child = fork;
    croak "Can't fork: $!" unless defined($child);
    return $child if $child;

    srand(); # after a fork, we need to reset the random seed
             # or we'll get the same numbers in both branches
    if ( $^O !~ /MSWin32/ ) {
        require POSIX;
        POSIX::setsid()
            or croak "Can't start a new session: $!";
    }
    $self->run(@_); # should never return
    exit;           # just to be sure
}