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sys_sem.h(0P) POSIX Programmer's Manual sys_sem.h(0P)
This 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.
sys/sem.h — XSI semaphore facility
#include <sys/sem.h>
The <sys/sem.h> header shall define the following symbolic constant
for use as a semaphore operation flag:
SEM_UNDO 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:
GETNCNT Get semncnt.
GETPID Get sempid.
GETVAL Get semval.
GETALL Get all cases of semval.
GETZCNT Get semzcnt.
SETVAL Set semval.
SETALL 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.
None.
None.
None.
sys_ipc.h(0p), sys_types.h(0p)
The System Interfaces volume of POSIX.1‐2008, semctl(3p), semget(3p),
semop(3p)
Portions 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 http://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
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 sys_sem.h(0P)
Pages that refer to this page: semctl(3p), semget(3p), semop(3p)