Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

sem_destroy(3) [osx man page]

SEM_DESTROY(3)						     Linux Programmer's Manual						    SEM_DESTROY(3)

NAME
sem_destroy - destroy an unnamed semaphore SYNOPSIS
#include <semaphore.h> int sem_destroy(sem_t *sem); Link with -pthread. DESCRIPTION
sem_destroy() destroys the unnamed semaphore at the address pointed to by sem. Only a semaphore that has been initialized by sem_init(3) should be destroyed using sem_destroy(). Destroying a semaphore that other processes or threads are currently blocked on (in sem_wait(3)) produces undefined behavior. Using a semaphore that has been destroyed produces undefined results, until the semaphore has been reinitialized using sem_init(3). RETURN VALUE
sem_destroy() returns 0 on success; on error, -1 is returned, and errno is set to indicate the error. ERRORS
EINVAL sem is not a valid semaphore. ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7). +--------------+---------------+---------+ |Interface | Attribute | Value | +--------------+---------------+---------+ |sem_destroy() | Thread safety | MT-Safe | +--------------+---------------+---------+ CONFORMING TO
POSIX.1-2001, POSIX.1-2008. NOTES
An unnamed semaphore should be destroyed with sem_destroy() before the memory in which it is located is deallocated. Failure to do this can result in resource leaks on some implementations. SEE ALSO
sem_init(3), sem_post(3), sem_wait(3), sem_overview(7) COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. Linux 2017-09-15 SEM_DESTROY(3)

Check Out this Related Man Page

sem_init(3RT)						    Realtime Library Functions						     sem_init(3RT)

NAME
sem_init - initialize an unnamed semaphore SYNOPSIS
cc [ flag... ] file... -lrt [ library... ] #include <semaphore.h> int sem_init(sem_t *sem, int pshared, unsigned int value); DESCRIPTION
The sem_init() function is used to initialize the unnamed semaphore referred to by sem. The value of the initialized semaphore is value. Following a successful call to sem_init(), the semaphore may be used in subsequent calls to sem_wait(3RT), sem_trywait(3RT), sem_post(3RT), and sem_destroy(3RT). This semaphore remains 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(3RT), sem_trywait(3RT), sem_post(3RT), and sem_destroy(3RT) operations. Only sem itself may be used for performing synchronization. The result of referring to copies of sem in calls to sem_wait(3RT), sem_try- wait(3RT), sem_post(3RT), and sem_destroy(3RT), 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(3RT), sem_trywait(3RT), sem_post(3RT), and sem_destroy(3RT) 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 VALUES
Upon successful completion, the function initializes the semaphore in sem. Otherwise, it returns -1 and sets errno to indicate the error. ERRORS
The sem_init() function will fail if: EINVAL The value argument exceeds SEM_VALUE_MAX. ENOSPC A resource required to initialize the semaphore has been exhausted, or the resources have reached the limit on semaphores (SEM_NSEMS_MAX). ENOSYS The sem_init() function is not supported by the system. EPERM The process lacks the appropriate privileges to initialize the semaphore. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
sem_destroy(3RT), sem_post(3RT), sem_wait(3RT), attributes(5), standards(5) SunOS 5.10 28 Jun 2002 sem_init(3RT)
Man Page