posix_spawn_file_actions_addopen
int posix_spawn_file_actions_addopen(posix_spawn_file_actions_t * __restrict,
posix_spawn_file_actions_addopen(&action, STDOUT_FILENO, "/dev/null", O_WRONLY, 0);
posix_spawn_file_actions_addopen(&action, STDERR_FILENO, "/dev/null", O_WRONLY, 0);
posix_spawn_file_actions_addopen(&action, STDIN_FILENO, "/dev/zero", O_RDONLY, 0);