PARA_INFO_LOG("starting stream writer: %s\n", glob);
open_filters(slot_num);
ret = para_exec_cmdline_pid(&s->wpid, glob, fds);
PARA_INFO_LOG("starting stream writer: %s\n", glob);
open_filters(slot_num);
ret = para_exec_cmdline_pid(&s->wpid, glob, fds);