sys_pidfd_open(9)

💅 sys_pidfd_open(9) — the Kernel API Manual, bestie edition 🎀

okay so this is <pink>sys_pidfd_open</pink> from the Kernel API Manual, and honestly? it's giving "tiny function, huge main character energy" ✨ let's get into it.

✨ NAME ✨

sys_pidfd_open — open a new pid file descriptor, periodt 💅

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🌸 SYNOPSIS 🌸

long sys_pidfd_open (pid_t pid , unsigned int flags );

that's it. that's the whole vibe. two little args, one long coming back at you 🫶

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🦋 ARGUMENTS 🦋

• pid — the pid you wanna get a pidfd for 💖 like, which task are we locking eyes with
• flags — the flags you're passing in 🎀 just hand them over

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👑 DESCRIPTION 👑

so what this does is create a brand-new pid file descriptor for the task identified by pid, and no cap — it's created with the O_CLOEXEC flag already set 🔥

⚠️ important lil caveat bestie: without the PIDFD_THREAD flag, the target task must be a thread-group leader. like, that's not optional. thread-group leader only. iykyk 💀

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⭐ RETURN ⭐

• on success → you get a cloexec pidfd back, slay 🌈
• on error → a negative errno number comes back 😭 (not me getting a negative number instead of a fd, fr fr)

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🧚 SEE ALSO 🧚

• Kernel file ./kernel/pid.c
• pidfd_get_task(9)
• pidfd_create(9)
• sys_pidfd_getfd(9)

go read those too, they're all connected, it's a whole ecosystem bestie 🦋✨

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and that's the page!! sourced from ./kernel, dated October 2026 — mwah, bye, go open some pidfds responsibly 💖🎀💅