_exit(3)

💅 _exit(3) — bestie, we're leaving. immediately. ✨

okay so this is the manual page for _exit and _Exit (yes that's a real name, no I will not be taking questions), part of the Library Functions Manual. It lives in the Standard C library — that's libc, and you link it with -lc. 🫶

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🌸 NAME 🌸

_exit, _Exit — terminate the calling process 💀

Like. that's it. that's the whole thing. the process said "I'm done" and meant it.

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📚 LIBRARY 📚

Standard C library — libc, -lc.

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✨ SYNOPSIS ✨

#include <unistd.h>

[[noreturn]] void _exit(int status);

#include <stdlib.h>

[[noreturn]] void _Exit(int status);

🎀 Feature Test Macro Requirements for glibc 🎀

(peep feature_test_macros(7) for the deets)

_Exit():

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

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🦋 DESCRIPTION 🦋

So _exit() terminates the calling process — and bestie, when I say terminate, I mean "immediately". No vibe check, no goodbye text, no nothing. 🫢

Here's the whole rundown of what happens:

• Any open file descriptors belonging to the process? Closed. done. 🚪
• Any children of the process? They get inherited by init(1) — or by the nearest "subreaper" process, which is defined through the use of the prctl(2) PR_SET_CHILD_SUBREAPER operation. 👑
• The process's parent gets sent a SIGCHLD signal. mom gets the notification fr fr 📣

The value status & 0xFF is returned to the parent process as the process's exit status, and it can be collected by the parent using one of the wait(2) family of calls.

And _Exit()? It is equivalent to _exit(). literally the same girl, different font. 💅

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😭 RETURN VALUE 😭

These functions do not return.

That's not a bug. That's the whole point. there is no return era. 🚫

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🌈 STANDARDS 🌈

• _exit() — POSIX.1-2024.
• _Exit() — C11, POSIX.1-2024.

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👑 HISTORY 👑

• _exit() — 4.3BSD, SVr4, POSIX.1-1988.
• _Exit() — C99, POSIX.1-2001.

Up to glibc 2.3, these functions invoked exit(2). Since glibc 2.3, they invoke exit_group(2), in order to terminate all of the threads in a process. yes queen, the entire group chat is leaving. 🎀

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💖 NOTES 💖

If you wanna read a whole discussion on the effects of an exit, the transmission of exit status, zombie processes, signals sent, and so on — go see exit(3). 🧟

So the tea: _exit() is like exit(3), but here's the plot twist — it does NOT call any functions registered with atexit(3) or on_exit(3). 🚫

Also, open stdio(3) streams are not flushed. all that buffered stuff? gone. bye. 👋

On the other hand, _exit() does close open file descriptors, and this may cause an unknown delay, waiting for pending output to finish. 😴

If the delay is undesired, it may be useful to call functions like tcflush(3) before calling _exit(). 💡

And whether any pending I/O is canceled, and which pending I/O may be canceled upon _exit(), is implementation-dependent. translation: it depends, don't @ me. 🙈

no cap — if you needed your atexit(3) handlers or your flushed stdio streams, this is NOT the function for you. this one leaves without saying goodbye. 💀

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🫶 SEE ALSO 🫶

execve(2), exit(2), exit_group(2), fork(2), kill(2), wait(2), wait4(2), waitpid(2), atexit(3), exit(3), on_exit(3), termios(7)

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this page came from Linux man-pages 6.20, dated 2026-07-02, and it's the _exit(3) era. periodt. 💅✨