tail head cat sleep
QR code linking to this page

Manual Pages  — SEM_INIT

NAME

sem_init – initialize an unnamed semaphore

CONTENTS

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 The sem argument is no longer valid after a successful call to sem_destroy(3).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 IEEE Std 1003.1-96 ("POSIX.1").

SEM_INIT (3) January 9, 2010

tail head cat sleep
QR code linking to this page


Please direct any comments about this manual page service to Ben Bullock. Privacy policy.

Some people open all the windows; wise wives welcome spring by moving the UNIX.