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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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SEM_INIT(3P) POSIX Programmer's Manual SEM_INIT(3P)
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.
sem_init — initialize an unnamed semaphore
#include <semaphore.h>
int sem_init(sem_t *sem, int pshared, unsigned value);
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.
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.
See Section 2.9.9, Synchronization Object Copies and Alternative
Mappings for further requirements.
Attempting to initialize an already initialized semaphore results
in undefined behavior.
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.
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.
None.
None.
None.
None.
sem_destroy(3p), sem_post(3p), sem_timedwait(3p), sem_trywait(3p)
The Base Definitions volume of POSIX.1‐2017, semaphore.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 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 .
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 2017 SEM_INIT(3P)
Pages that refer to this page: semaphore.h(0p), sem_close(3p), semctl(3p), sem_destroy(3p), semget(3p), semop(3p), sigaction(3p)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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