sem_init(3C)							  sem_init(3C)

NAME    [Toc]    [Back]

     sem_init -	initialize a posix unnamed semaphore

SYNOPSIS    [Toc]    [Back]

     #include <semaphore.h>

     int sem_init(sem_t	*sem<b>, int pshared<b>, unsigned int	value<b>);

DESCRIPTION    [Toc]    [Back]

     sem_init initializes the unnamed semaphore	located	at address sem.	 The
     address sem may reside anywhere in	the calling processes address space,
     but if the	semaphore is intended to be shared across process boundaries,
     sem must reside in	shared memory.

     The pshared argument is used to specify whether the semaphore is intended
     to	be shared across process boundaries or only used locally by threads of
     execution within a	common process.	 If pshared is set to zero, then the
     semaphore is not intended for sharing across process boundaries.
     Conversely, a non-zero pshared value indicates any	process	having read
     and write access to address sem, may perform semaphore operations on sem.
     Unnamed semaphores	have been optimized for	local thread usage, delivering
     increased performance within posix	thread applications [see
     pthread_create(3P)].

     The initial value of the semaphore	is specified by	value, which may be
     any non-negative number less than {SEM_VALUE_MAX} [see sysconf(3C)].

     POSIX semaphores are compatible across all	MIPS ABIs: o32,	n32 and	64.

     Once a semaphore is initialized, processes	may execute the	following
     semaphore operations: sem_post, sem_wait, sem_trywait, sem_getvalue,
     sem_destroy.

     sem_init will fail	if one or more of the following	are true:

     [EINVAL]	 The value parameter was set to	a number greater than
		 {SEM_VALUE_MAX}.

     [ENOSPC]	 The resources required	to initialize the semaphore have been
		 depleted.

     [EPERM]	 The calling process lacks the permissions required to
		 initialize the	semaphore.

SEE ALSO    [Toc]    [Back]

     sem_destroy(3C), sem_getvalue(3C),	sem_post(3C), sem_wait(3C),
     sem_trywait(3C), sem_open(3C), sem_close(3C), sem_unlink(3C),
     shm_open(3C), sysconf(3C),	mmap(3C)







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sem_init(3C)							  sem_init(3C)



DIAGNOSTICS
     Upon successful completion, a value of 0 is returned to the calling
     process. Otherwise, a value of -1 is returned and errno is	set to
     indicate the error.


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