Define $ENV{SERVER_STARTER_PORT} in your script. if (-S $socket) { warn "removing existing socket file:$socket"; unlink $socket or die "failed to remove existing socket file:$socket:$!"; } unlink $socket; my $sock = IO::Socket::UNIX->new( Listen => Socket::SOMAXCONN(), Local => $socket, ) or die "failed to listen to file $socket:$!"; $ENV{SERVER_STARTER_PORT} = $socket."=".$sock->fileno; my $loade