sem_init(3) [netbsd man page]

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  sem is no longer valid after a successful call to sem_destroy.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 indi-
     cate 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
     intention 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

sem_init(3C)						   Standard C Library Functions 					      sem_init(3C)

NAME

       sem_init - initialize an unnamed semaphore

SYNOPSIS

       #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(3C),  sem_trywait(3C),  sem_post(3C),
       and sem_destroy(3C). 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(3C), sem_trywait(3C), sem_post(3C), and sem_destroy(3C) operations.

       Only sem itself may be used for performing synchronization. The result of referring to copies of sem in	calls  to  sem_wait(3C),  sem_try-
       wait(3C), sem_post(3C), and sem_destroy(3C), 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(3C), sem_trywait(3C), sem_post(3C), and sem_destroy(3C) 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	     |Committed 		   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+
       |Standard		     |See standards(5). 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       sem_destroy(3C), sem_post(3C), sem_wait(3C), attributes(5), standards(5)

SunOS 5.11							    5 Feb 2008							      sem_init(3C)