PROLOGThis manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
NAMEsys/sem.h --- XSI semaphore facility
DESCRIPTIONThe <sys/sem.h> header shall define the following symbolic constant for use as a semaphore operation flag:
- 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
header shall define the
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().
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.
unsigned short sem_num Semaphore number. short sem_op Semaphore operation. short sem_flg Operation flags.
int semctl(int, int, int, ...); int semget(key_t, int, int); int semop(int, struct sembuf *, size_t);
The following sections are informative.
SEE ALSO<sys_ipc.h>, <sys_types.h> The System Interfaces volume of POSIX.1-2008, semctl(), semget(), semop()
COPYRIGHTPortions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at www.unix.org/online.html .
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 www.kernel.org/doc/man-pages/reporting_bugs.html .