pthread_once(3)

💖 pthread_once(3) 💖

okay bestie, welcome to the Library Functions Manual page for pthread_once — yes this is a section 3 man page and yes it's about to be your new fave 💅

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✨ NAME ✨

pthread_once — once-only initialization

like... it literally does the thing one time only. that's the whole vibe. no cap.

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🌸 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;

yes bestie the synopsis really looks like that, i didn't touch it, i promise 🫶

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🦋 DESCRIPTION 🦋

okay so the whole point of pthread_once() is to make sure that a lil piece of initialization code runs at most once. at most. not twice, not "oops i did it again", once. 👑

The once_control argument points to a static or extern variable that's statically initialized to PTHREAD_ONCE_INIT. that's your little flag, your little bookmark, your little "already did this" sticker ✨

The first time pthread_once() gets 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. so it does the thing and then it writes down that it did the thing. main character behavior, honestly.

Subsequent calls to pthread_once() with the same once_control argument do nothing. nothing!! it's giving "i said what i said" 💀 zero drama, zero re-runs.

fr fr this is the entire trick: one pointer, one init function, one guaranteed single execution. periodt.

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💜 RETURN VALUE 💜

pthread_once() always returns 0.

always. like, that's it. that's the return value. iconic, no notes 🌈

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🎀 ERRORS 🎀

None.

not a single one. she doesn't miss. 💖

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🌟 little sign-off 🌟

this page came to you from Linux man-pages 6.20, dated 2025-05-17 — and that's the whole pthread_once(3) moment. go initialize something exactly once, bestie. i'm obsessed 🦋✨💅