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 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_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 sem is no longer valid after a successful call to sem_destroy.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

It is an error to call sem_destroy() on a named semaphore created by sem_open().

sem_init() will fail if:

[EINVAL]

value exceeds SEM_VALUE_MAX.

[ENOSPC]

Memory allocation error.

SEE ALSO

sem_destroy(3), sem_getvalue(3), sem_open(3), sem_post(3), sem_wait(3)

STANDARDS

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