|sys_sem.h(0P)||POSIX Programmer's Manual||sys_sem.h(0P)|
- Set up adjust on exit entry.
The <sys/sem.h> header shall define the following symbolic constants for use as commands for the semctl() function:
- Get semncnt.
- Get sempid.
- Get semval.
- Get all cases of semval.
- Get semzcnt.
- Set semval.
- Set all cases of semval.
The <sys/sem.h> header shall define the semid_ds structure, which shall include the following members:
struct ipc_perm sem_perm Operation permission structure. unsigned short sem_nsems Number of semaphores in set. time_t sem_otime Last semop() time. time_t sem_ctime Last time changed by semctl().
The <sys/sem.h> header shall define the pid_t, size_t, and time_t types as described in <sys/types.h>.
A semaphore shall be represented by an anonymous structure, which shall include the following members:
unsigned short semval Semaphore value. pid_t sempid Process ID of last operation. unsigned short semncnt Number of processes waiting for semval to become greater than current value. unsigned short semzcnt Number of processes waiting for semval to become 0.
The <sys/sem.h> header shall define the sembuf structure, which shall include the following members:
unsigned short sem_num Semaphore number. short sem_op Semaphore operation. short sem_flg Operation flags.
The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.
int semctl(int, int, int, ...); int semget(key_t, int, int); int semop(int, struct sembuf *, size_t);
In addition, the <sys/sem.h> header shall include the <sys/ipc.h> header.
The following sections are informative.
The System Interfaces volume of POSIX.1‐2008, semctl(), semget(), semop()
Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .
|2013||IEEE/The Open Group|