proc_pid_syscall(5)

💖 proc_pid_syscall — bestie's guide to stalking a syscall 💖

okay so this is one of those proc files and it's lowkey iconic. it lives at /proc/pid/syscall and it's literally a live feed of whatever syscall your process is doing right now. let's get into it 🫶

(i'm the proc_pid_syscall page btw, from section 5 of the manual — file formats, iykyk ✨)

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✨ NAME ✨

/proc/pid/syscall — the currently executed system call 👀

like that's it, that's the whole vibe. no notes.

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🌸 DESCRIPTION 🌸

🎀 the file itself

/proc/pid/syscall (since Linux 2.6.27)

so basically this file spills the tea on the system call your process is running at this exact moment. it shows you:

• the system call number 🔢
• the argument registers 💅
• and right after those, the values of the stack pointer and program counter registers 🌟

and here's the thing — it exposes all six argument registers, even though most system calls are out here using way fewer of them. generous queen behavior honestly 👑

😭 when the process is blocked (but not in a syscall)

plot twist! if the process is blocked but it's not sitting inside a system call? the file hits you with:

• -1 where the system call number should be 😳
• and then just the values of the stack pointer and program counter, nothing else

like it's giving "no syscall here bestie, but here's where we are" 🕵️

🏃 when the process is not blocked

if the process is not blocked, the file is literally just the string:

running

that's it. that's the whole file. main character energy, minimal words 💀✨

⚠️ important detail alert

this file is only present if the kernel was configured with CONFIG_HAVE_ARCH_TRACEHOOK. no config, no file, no cap 🚫

🔐 who's allowed in

permission to access this file is governed by a ptrace access mode PTRACE_MODE_ATTACH_FSCREDS check — go see ptrace(2) for the full rundown, i'm not gonna gatekeep the details for you 🫶

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👑 SEE ALSO 👑

• proc(5)

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and that's the page!! go forth and peek at syscalls responsibly, bestie 🌈🦋💜

sending you love from the Linux man-pages 6.20 girlies, dated 2026-02-08 — mwah, stay curious, drink water, and don't forget to read proc(5) ⭐🎀