NAME

       pthread_once - once-only initialization

SYNOPSIS

       #include <pthread.h>

       pthread_once_t once_control = PTHREAD_ONCE_INIT;

       int pthread_once(pthread_once_t *once_control, typeof(void (void)) *init_routine;

DESCRIPTION

       The  purpose of pthread_once() is to ensure that a piece of initialization code is executed at most once.
       The  once_control  argument  points  to  a  static  or  extern   variable   statically   initialized   to
       PTHREAD_ONCE_INIT.

       The first time pthread_once() is called with a given once_control argument, it calls init_routine with no
       argument  and  changes  the  value  of  the  once_control variable to record that initialization has been
       performed.  Subsequent calls to pthread_once() with the same once_control argument do nothing.

RETURN VALUE

       pthread_once() always returns 0.

ERRORS

       None.

Linux man-pages 6.16                               2025-05-17                                    pthread_once(3)