id_t
extern int getpriority(int which, id_t who);
extern int setpriority(int which, id_t who, int priority);
extern int waitid(idtype_t idType, id_t id, siginfo_t *info, int options);
getpriority(int which, id_t who)
setpriority(int which, id_t who, int value)
waitid(idtype_t idType, id_t id, siginfo_t* info, int options)