proc_pid_cmdline(5)

💖 NAME 💖

okay so bestie, gather round: /proc/pid/cmdline — it's the command line, fr fr 🫶

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✨ DESCRIPTION ✨

🌸 /proc/pid/cmdline

So like, this file is read-only and it holds the complete command line for the process — unless the process is a zombie 😭. And if it is a zombie? There's literally nothing in this file. Like, a read on this file will return 0 characters. It's giving empty. It's giving ghosted. 💀

For processes that are still running, the command-line arguments show up in this file in the exact same layout as they do in process memory. And if the process is well-behaved (as it should be 💅), it's a set of strings separated by null bytes ('\0'), with a further null byte after the last string. Periodt. ✨

That's the common case, yeah — but bestie, processes have the freedom to override the memory region and break assumptions about the contents or format of the /proc/pid/cmdline file. Not them being chaotic 🙈.

Also: if, after an execve(2), the process modifies its argv strings, those changes will show up here. But heads up — this is not the same thing as modifying the argv array. Different thing entirely, iykyk.

And on top of that, a process may change the memory location that this file refers to via prctl(2) operations such as PR_SET_MM_ARG_START. Sneaky. Iconic. 👑

Think of this file as the command line that the process wants you to see. The edited version. The main character cut. 🎬

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🦋 SEE ALSO 🦋

• proc(5)

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and that's the whole vibe, bestie — this page came to you straight from Linux man-pages 6.20, dated 2026-02-08, for proc_pid_cmdline(5) 💜 slay, stay curious, and never trust a zombie's cmdline 🧚✨