oracular (3) sem_init.3posix.gz

Provided by: manpages-posix-dev_2017a-2_all bug

PROLOG
       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.


NAME
       sem_init — initialize an unnamed semaphore


SYNOPSIS
       #include <semaphore.h>

       int sem_init(sem_t *sem, int pshared, unsigned value);


DESCRIPTION
       The  sem_init()  function  shall  initialize  the unnamed semaphore referred to by sem.  The value of the
       initialized semaphore shall be value.  Following a successful call to sem_init(), the  semaphore  may  be
       used  in  subsequent  calls to sem_wait(), sem_timedwait(), sem_trywait(), sem_post(), and sem_destroy().
       This semaphore shall remain 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(),
       sem_timedwait(), sem_trywait(), sem_post(), and sem_destroy() operations.

       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(), sem_timedwait(), sem_trywait(), sem_post(), and
       sem_destroy() operations.

       See Section 2.9.9, Synchronization Object Copies and Alternative Mappings for further requirements.

       Attempting to initialize an already initialized semaphore results in undefined behavior.


RETURN VALUE
       Upon successful completion, the sem_init() function shall initialize the semaphore in sem and  return  0.
       Otherwise, it shall return -1 and set errno to indicate the error.


ERRORS
       The sem_init() function shall fail if:

       EINVAL The value argument exceeds {SEM_VALUE_MAX}.

       ENOSPC A  resource  required  to  initialize the semaphore has been exhausted, or the limit on semaphores
              ({SEM_NSEMS_MAX}) has been reached.

       EPERM  The process lacks appropriate privileges to initialize the semaphore.

       The following sections are informative.


EXAMPLES
       None.


APPLICATION USAGE
       None.


RATIONALE
       None.


FUTURE DIRECTIONS
       None.


SEE ALSO
       sem_destroy(), sem_post(), sem_timedwait(), sem_trywait()

       The Base Definitions volume of POSIX.1‐2017, <semaphore.h>


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical  and  Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee  document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .