sem_init(3) - NetBSD Manual Pages

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SEM_INIT(3)             NetBSD 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.

     Following a successful call to sem_init(), sem can be used as an argument
     in subsequent calls to sem_wait(), sem_timedwait(), 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  sem is no longer valid after a successful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]           There was memory allocation error, or the limit on
                        available semaphores (SEM_NSEMS_MAX) has been
                        exceeded.

     [EPERM]            Unable to initialize a shared semaphore.


SEE ALSO

     sem_destroy(3), sem_post(3), sem_timedwait(3), sem_trywait(3),
     sem_wait(3)


STANDARDS

     sem_init() conforms to ISO/IEC 9945-1:1996 (``POSIX.1'').

NetBSD 9.4                     February 21, 2019                    NetBSD 9.4