sysfs_emit_at(9)

📦 version 7.3.1, in nixpkgs unstable

✨ sysfs_emit_at(9) ✨

okay so bestie, welcome to the Kernel API Manual entry for sysfs_emit_at — yes it's a kernel function, yes it's a 9-section manpage, and yes we're gonna get through it together 💅

🌸 NAME 🌸

sysfs_emit_at — literally the scnprintf equivalent, except it knows about the PAGE_SIZE buffer. no cap. it's giving "snprintf but self-aware" 🎀

🦋 SYNOPSIS 🦋

int sysfs_emit_at (char *buf , int at , const char *fmt , ... );

that's the whole signature, bestie. int in, int out, and a little ... at the end doing its mysterious variadic thing ✨

💖 ARGUMENTS 💖

  • buf — start of the PAGE_SIZE buffer. this is where the magic lives 🫶
  • at — offset in buf to start writing, in bytes. and it must satisfy at must be >= 0 && < PAGE_SIZE — like, this is not a suggestion, it's a vibe check you cannot fail 😭
  • fmt — the format. your classic format string, you know her 👑
  • ... — optional arguments to fmt. the little squad that tags along 🧚

🌈 DESCRIPTION 🌈

Returns the number of characters written, starting at &buf[at]. that's it, that's the whole description, and honestly? iconic. short, sweet, to the point 💜

lowkey the key detail here is that at is an offset, so you're not writing at the beginning of the buffer, you're writing at &buf[at] — and the count you get back is the chars written from that point 🔥

⭐ SEE ALSO ⭐

the whole friend group, in the kernel file ./fs/sysfs/file.c:

like, that's the entire sysfs cinematic universe, and you're gonna wanna know all of them eventually 💀💖

💅 friendly reminder that ./fs/sysfs is the kernel file path that goes with this page, so if you ever need to go read the source, that's the door, bestie, go knock 🚪✨

and that's the page!! from ./fs/sysfs, October 2026 edition — go forth and emit responsibly, mwah 🎀💜🦋

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