getgid(2)

💖 getgid(2) — the System Calls Manual page, but make it make sense ✨

okay bestie, welcome to section 2 of the manual — the System Calls Manual, to be precise — and today we're getting into getgid. it's short, it's sweet, it's giving "who even am I" but for groups. let's go 🫶

---

🌸 NAME 🌸

getgid, getegid — get group identity 👑

---

📚 LIBRARY 📚

Standard C library (libc, -lc) — yes queen, you gotta link the libc, always

---

✨ SYNOPSIS ✨

#include <unistd.h>

gid_t getgid(void);
gid_t getegid(void);

look at them. two little functions. zero arguments. no cap. 💅

---

🦋 DESCRIPTION 🦋

• getgid() — hands you back the real group ID of the calling process. that's your actual, true, main-character group identity, no makeup on 💖
• getegid() — hands you back the effective group ID of the calling process. that's the one the kernel actually checks when you try to do stuff. it's giving "what you're wearing to the permission party" ✨

both return a gid_t, and both take void, so you literally cannot pass anything wrong to them. icon behavior fr fr 🙈

---

💀 ERRORS 💀

not a single one. these functions are always successful and never modify errno. no drama, no failure, no chaos. they simply ate and left no crumbs 😭👑

ngl if you're out here checking errno after calling getgid(), bestie... that's not the vibe. there's nothing to check. it's fine. it's always fine.

---

🌈 VERSIONS 🌈

okay so this is the one little plot twist in our story 🌀

• On Alpha, instead of a pair of getgid() and getegid() system calls, there's a single getxgid() system call, and it returns a pair — the real and effective GIDs together, like a two-for-one deal 💅
• The glibc getgid() and getegid() wrapper functions transparently deal with this. so you don't have to do a thing. slay.
• For the details regarding register mapping, go peek at syscall(2) 🧚

---

⭐ STANDARDS ⭐

POSIX.1-2024. it's official, it's standardized, it's certified bestie behavior 🎀

---

🎀 HISTORY 🎀

• 4.3BSD, POSIX.1-1988 — the origin story, we love a legacy 👑
• The original Linux getgid() and getegid() system calls supported only 16-bit group IDs. tiny. adorable. limited. 😭
• Subsequently, Linux 2.4 added getgid32() and getegid32(), supporting 32-bit IDs. glow up ✨
• The glibc getgid() and getegid() wrapper functions transparently deal with the variations across kernel versions. so again — you worry about nothing, the wrappers handle the lore 🫶

---

👀 SEE ALSO 👀

• getresgid(2)
• setgid(2)
• setregid(2)
• credentials(7)

---

that's the whole page bestie, we did it, we understood group identity, we did NOT touch errno, and we moved on with our lives 💜

Linux man-pages 6.20 · 2026-02-08 — mwah, kiss the manual goodbye, ily, go check your gids 💅💖