aio_fsync(3)

✨ aio_fsync(3) ✨

okay bestie, so you're deep in the librt corner of the library (that's the real-time library, -lrt, keep it 💅) and this is the Library Functions Manual page for aio_fsync. it's giving asynchronous file sync, it's giving "yes i queued your write, no i did not wait for it." let's get into it 🦋

---

🌸 NAME 🌸

aio_fsync — asynchronous file synchronization. that's it, that's the whole vibe ✨

---

🎀 LIBRARY 🎀

the real-time library, aka librt, and you link it like this:

-lrt

that's the one, no cap 🫶

---

🔥 SYNOPSIS 🔥

#include <aio.h>

int aio_fsync(int op, struct aiocb *aiocbp);

so two args, op and a pointer to a struct aiocb called aiocbp. she's simple like that 💖

---

💜 DESCRIPTION 💜

so aio_fsync() does a sync on all the outstanding asynchronous I/O operations that are associated with aiocbp->aio_fildes. and if you're like "wait what even is the aiocb structure," go read aio(7), it has the whole description, i'm not doing that to you here 🫶

more precisely (because apparently we're being precise now, okay, periodt):

• if op is O_SYNC, then all currently queued I/O operations shall be completed as if by a call of fsync(2)
• if op is O_DSYNC, this call is the asynchronous analog of fdatasync(2)

and here's the thing bestie — this is a request only; it does not wait for I/O completion. so don't be out here assuming it finished, because it did not, it just put in the request like a text message you send and immediately put your phone down ✨

apart from aio_fildes, the only field in the structure pointed to by aiocbp that this call uses is the aio_sigevent field — that's a sigevent structure, described over in sigevent(3type) — and it tells you what kind of asynchronous notification you want at completion. every other field? ignored. not used. not read. don't @ me 😭

---

💖 RETURN VALUE 💖

• on success — meaning the sync request was successfully queued — this function returns 0 👑
• on error it returns -1, and errno gets set to tell you what went wrong

---

🩷 ERRORS 🩷

like, the whole errno roster:

• EAGAIN — out of resources. she's tapped out, no more to give 💀
• EBADF — aio_fildes is not a valid file descriptor open for writing
• EINVAL — synchronized I/O is not supported for this file, or op is not O_SYNC or O_DSYNC
• ENOSYS — aio_fsync() is not implemented 🙈

---

🦋 ATTRIBUTES 🦋

for the whole explanation of what these terms even mean, go check out attributes(7). here's the rundown:

• aio_fsync() — Thread safety: MT-Safe 🔥

MT-Safe means she's safe to call from multiple threads, slay 💅

---

⭐ STANDARDS ⭐

POSIX.1-2008. that's the standard she follows, periodt ✨

---

🌈 HISTORY 🌈

• glibc 2.1
• POSIX.1-2001

so she's been around a minute, an icon honestly 👑

---

💅 SEE ALSO 💅

go get your read on, bestie:

• aio_cancel(3)
• aio_error(3)
• aio_read(3)
• aio_return(3)
• aio_suspend(3)
• aio_write(3)
• lio_listio(3)
• aio(7)
• sigevent(3type)

---

and that's the page!! this came to you from Linux man-pages 6.20, dated 2026-02-08, and honestly that's such a cute little timestamp. stay async, stay synced, queue your requests and don't wait around for them 🫶💖✨