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SEM_INIT(3) FreeBSD Library Functions Manual SEM_INIT(3) NAME sem_init - initialize an unnamed semaphore LIBRARY Standard C Library (libc, -lc) SYNOPSIS #include <semaphore.h> int sem_init(sem_t *sem, int pshared, unsigned int value); DESCRIPTION The sem_init() function initializes the unnamed semaphore pointed to by sem to have the value value. A non-zero value for pshared specifies a shared semaphore that can be used by multiple processes, the semaphore should be located in shared memory region (see mmap(2), shm_open(2), and shmget(2)), any process having read and write access to address sem can perform semaphore operations on sem. Following a successful call to sem_init(), sem can be used as an argument in subsequent calls to sem_wait(3), sem_trywait(3), sem_post(3), and sem_destroy(3). The sem argument is no longer valid after a successful call to sem_destroy(3). RETURN VALUES The sem_init() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error. ERRORS The sem_init() function will fail if: [EINVAL] The value argument exceeds SEM_VALUE_MAX. [ENOSPC] Memory allocation error. SEE ALSO sem_destroy(3), sem_getvalue(3), sem_post(3), sem_trywait(3), sem_wait(3) STANDARDS The sem_init() function conforms to ISO/IEC 9945-1:1996 ("POSIX.1"). FreeBSD 14.1-RELEASE-p8 January 9, 2010 FreeBSD 14.1-RELEASE-p8