pthread_once(3)            Library Functions Manual            pthread_once(3)

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, void (*init_routine)
       (void));

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 6.7               2023-10-31                   pthread_once(3)