mark -qo (without argument) obsolete Its behavior (online detect and send over the available route) is included in -q. In the -qo case no local mail would be sent, but why would be not want to do so? We might use -qo (without arg) for something more useful in the future.

FILE *peopen(const char *command, const char *type, char *const envp[], int *ret_pid);

FILE *peidopen(const char *command, const char *type, char *const envp[], int *ret_pid, uid_t uid, gid_t gid);