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 sem is no longer valid after a successful call to sem_destroy.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