SEM_DESTROY(3P) POSIX Programmer's Manual SEM_DESTROY(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond-
ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
NAME
sem_destroy - destroy an unnamed semaphore (REALTIME)
SYNOPSIS
#include <semaphore.h>
int sem_destroy(sem_t *sem);
DESCRIPTION
The sem_destroy() function shall destroy the unnamed semaphore indicated by sem. Only a semaphore that was created using sem_init() may be
destroyed using sem_destroy(); the effect of calling sem_destroy() with a named semaphore is undefined. The effect of subsequent use of the
semaphore sem is undefined until sem is reinitialized by another call to sem_init().
It is safe to destroy an initialized semaphore upon which no threads are currently blocked. The effect of destroying a semaphore upon which
other threads are currently blocked is undefined.
RETURN VALUE
Upon successful completion, a value of zero shall be returned. Otherwise, a value of -1 shall be returned and errno set to indicate the
error.
ERRORS
The sem_destroy() function shall fail if:
EINVAL The sem argument is not a valid semaphore.
The sem_destroy() function may fail if:
EBUSY There are currently processes blocked on the semaphore.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The sem_destroy() function is part of the Semaphores option and need not be available on all implementations.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
semctl(), semget(), semop(), sem_init(), sem_open(), the Base Definitions volume of IEEE Std 1003.1-2001, <semaphore.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. 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.opengroup.org/unix/online.html .
IEEE /The Open Group 2003 SEM_DESTROY(3P)
Check Out this Related Man Page
SEM_INIT(3P) POSIX Programmer's Manual SEM_INIT(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond-
ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
NAME
sem_init -- initialize an unnamed semaphore
SYNOPSIS
#include <semaphore.h>
int sem_init(sem_t *sem, int pshared, unsigned value);
DESCRIPTION
The sem_init() function shall initialize the unnamed semaphore referred to by sem. The value of the initialized semaphore shall be value.
Following a successful call to sem_init(), the semaphore may be used in subsequent calls to sem_wait(), sem_timedwait(), sem_trywait(),
sem_post(), and sem_destroy(). This semaphore shall remain usable until the semaphore is destroyed.
If the pshared argument has a non-zero value, then the semaphore is shared between processes; in this case, any process that can access the
semaphore sem can use sem for performing sem_wait(), sem_timedwait(), sem_trywait(), sem_post(), and sem_destroy() operations.
Only sem itself may be used for performing synchronization. The result of referring to copies of sem in calls to sem_wait(), sem_timed-
wait(), sem_trywait(), sem_post(), and sem_destroy() is undefined.
If the pshared argument is zero, then the semaphore is shared between threads of the process; any thread in this process can use sem for
performing sem_wait(), sem_timedwait(), sem_trywait(), sem_post(), and sem_destroy() operations. The use of the semaphore by threads other
than those created in the same process is undefined.
Attempting to initialize an already initialized semaphore results in undefined behavior.
RETURN VALUE
Upon successful completion, the sem_init() function shall initialize the semaphore in sem and return 0. Otherwise, it shall return -1 and
set errno to indicate the error.
ERRORS
The sem_init() function shall fail if:
EINVAL The value argument exceeds {SEM_VALUE_MAX}.
ENOSPC A resource required to initialize the semaphore has been exhausted, or the limit on semaphores ({SEM_NSEMS_MAX}) has been reached.
EPERM The process lacks appropriate privileges to initialize the semaphore.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
sem_destroy(), sem_post(), sem_timedwait(), sem_trywait()
The Base Definitions volume of POSIX.1-2008, <semaphore.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technol-
ogy -- 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 Stan-
dard 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 SEM_INIT(3P)