1SEM_CLOSE(3P) POSIX Programmer's Manual SEM_CLOSE(3P)
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6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
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12 sem_close — close a named semaphore
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15 #include <semaphore.h>
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17 int sem_close(sem_t *sem);
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20 The sem_close() function shall indicate that the calling process is
21 finished using the named semaphore indicated by sem. The effects of
22 calling sem_close() for an unnamed semaphore (one created by
23 sem_init()) are undefined. The sem_close() function shall deallocate
24 (that is, make available for reuse by a subsequent sem_open() by this
25 process) any system resources allocated by the system for use by this
26 process for this semaphore. The effect of subsequent use of the sema‐
27 phore indicated by sem by this process is undefined. If any threads in
28 the calling process are currently blocked on the semaphore, the behav‐
29 ior is undefined. If the semaphore has not been removed with a suc‐
30 cessful call to sem_unlink(), then sem_close() has no effect on the
31 state of the semaphore. If the sem_unlink() function has been success‐
32 fully invoked for name after the most recent call to sem_open() with
33 O_CREAT for this semaphore, then when all processes that have opened
34 the semaphore close it, the semaphore is no longer accessible.
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37 Upon successful completion, a value of zero shall be returned. Other‐
38 wise, a value of -1 shall be returned and errno set to indicate the
39 error.
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42 The sem_close() function may fail if:
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44 EINVAL The sem argument is not a valid semaphore descriptor.
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46 The following sections are informative.
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49 None.
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52 None.
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55 None.
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58 None.
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61 semctl(), semget(), semop(), sem_init(), sem_open(), sem_unlink()
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63 The Base Definitions volume of POSIX.1‐2017, <semaphore.h>
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66 Portions of this text are reprinted and reproduced in electronic form
67 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
68 table Operating System Interface (POSIX), The Open Group Base Specifi‐
69 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
70 Electrical and Electronics Engineers, Inc and The Open Group. In the
71 event of any discrepancy between this version and the original IEEE and
72 The Open Group Standard, the original IEEE and The Open Group Standard
73 is the referee document. The original Standard can be obtained online
74 at http://www.opengroup.org/unix/online.html .
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76 Any typographical or formatting errors that appear in this page are
77 most likely to have been introduced during the conversion of the source
78 files to man page format. To report such errors, see https://www.ker‐
79 nel.org/doc/man-pages/reporting_bugs.html .
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83IEEE/The Open Group 2017 SEM_CLOSE(3P)