iovec(3type)

💖 iovec — the 3type page, but make it a vibe

okay so bestie, welcome to iovec(3type) 💅 this is a type, not a function, not a syscall, just a lil data structure that the kernel girlies use to gossip about memory ✨ strap in.

---

🎀 NAME 🎀

iovec — Vector I/O data structure 🦋

like. it's a vector. of I/O. the name ate and left no crumbs.

---

📚 LIBRARY 📚

Standard C library (libc) 💜

---

✨ SYNOPSIS ✨

#include <sys/uio.h>

struct iovec {
    void   *iov_base;  /* Starting address */
    size_t  iov_len;   /* Size of the memory pointed to by iov_base. */
};

LOOK AT HER. two fields. that's it. that's the whole girl. main character energy fr fr 👑

---

🌸 DESCRIPTION 🌸

So basically, an iovec describes a region of memory — it kicks off at the iov_base address and it's iov_len bytes long. that's the whole deal, no cap 🫶

But here's where it gets iconic: system calls don't just use one of these — they use arrays of them. each element in the array is its own memory region, and the entire array together is a whole vector of memory regions 🌈💫

and the maximum number of iovec structures you can fit in that array? limited by IOV_MAX bestie, which is defined in <limits.h>, or you can grab it by calling sysconf(_SC_IOV_MAX) 💅

lowkey important: hit that limit and things get spicy, so know your IOV_MAX iykyk 💀

---

📏 STANDARDS 📏

POSIX.1-2024. periodt 💖

---

🕰️ HISTORY 🕰️

• SUSv1
• POSIX.1-2001 XSI

the way she's been around since SUSv1 and still serves looks?? generational 😭✨

---

📝 NOTES 📝

plot twist bestie: this type is also provided by another header —

• <sys/socket.h>

so if you see it there, no you didn't hallucinate 🙈 she gets around 💅

---

👀 SEE ALSO 👀

• process_madvise(2)
• readv(2)

go read those next, bestie, they're the ones actually doing stuff with her 🦋

---

and that's the whole page!! 🌸 this was the Linux man-pages 6.20 version, dated 2026-01-09 — so you know it's fresh, no cap 💖 mwah, go forth and vector your I/O 💅✨🫶