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SEM_INIT(3)		 BSD Library Functions Manual		   SEM_INIT(3)

NAME
     sem_init — initialize an unnamed semaphore

LIBRARY
     POSIX Real-time Library (librt, -lrt)

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, which this
     implementation is not capable of.

     Following a successful call to sem_init(), sem can be used as an argument
     in subsequent calls to sem_wait, sem_trywait, sem_post, and sem_destroy.
     sem is no longer valid after a successful call to sem_destroy.

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
     sem_init() will fail if:

     [EINVAL]		value exceeds SEM_VALUE_MAX.

     [ENOSPC]		Memory allocation error.

     [EPERM]		Unable to initialize a shared semaphore.

SEE ALSO
     sem_destroy(3), sem_post(3), sem_trywait(3), sem_wait(3)

STANDARDS
     sem_init() conforms to ISO/IEC 9945-1:1996 (“POSIX.1”).

     This implementation does not support shared semaphores, and reports this
     fact by setting errno to EPERM.  This is perhaps a stretch of the inten‐
     tion of POSIX, but is compliant, with the caveat that sem_init() always
     reports a permissions error when an attempt to create a shared semaphore
     is made.

BSD			       January 22, 2003				   BSD

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