fcloseall(3)

✨ fcloseall(3) ✨

okay bestie, so this one lives in the Library Functions Manual 💖 — it's a libc era icon and we're gonna get into it.

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🌸 NAME 🌸

fcloseall — close all open streams. every single one. no survivors. periodt 💅

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📚 LIBRARY 📚

Standard C library (libc, -lc) 🫶

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🦋 SYNOPSIS 🦋

#define _GNU_SOURCE         /* See feature_test_macros(7) */
#include <stdio.h>

int fcloseall(void);

that #define _GNU_SOURCE line is not optional, bestie — you need it, and the comment is literally pointing you at feature_test_macros(7) if you wanna know why 👀

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💜 DESCRIPTION 💜

So. fcloseall() closes all of the calling process's open streams. Like, every stream that process has open. all of them. it's giving spring cleaning 🧹✨

Buffered output for each stream gets written out before it's closed — same energy as fflush(3) — and buffered input just gets dropped on the floor. discarded. gone. bye 🙈

and okay, here's the part that makes people gasp: the standard streams — stdin, stdout, and stderr — are also closed. yes, those ones. all three. 💀

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🔥 RETURN VALUE 🔥

• 0 — slay, everything closed successfully 🎀
• EOF — on error, that's what you get 😭

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👑 ATTRIBUTES 👑

For an explanation of the terms used in this section, see attributes(7). (yes, actually go look, it's right there ✨)

• Interface: fcloseall()
• Attribute: Thread safety
• Value: MT-Unsafe race:streams

and the reason for that spicy value? fcloseall() does not lock the streams, so it is not thread-safe. no cap. if you're threading, this is a vibe check that you will fail 🚩

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🌈 STANDARDS 🌈

GNU. 🐃 (it's a GNU thing, okay, it's not in the standard C lineup — iykyk)

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💖 SEE ALSO 💖

close(2), fclose(3), fflush(3), fopen(3), setbuf(3)

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and that's the whole page, bestie! 🫶 this little ditty came to you courtesy of Linux man-pages 6.20, dated 2026-02-08, and yes the filename at the end is literally fcloseall(3) again because manpages love a dramatic repetition. go close some streams. not your stdout tho. maybe. your call. 💅✨