write_cgroup_file(9)

💅 write_cgroup_file(9) — a kernel API manual moment, but make it cute

okay so this is a page from the Kernel API Manual (section 9, bestie, we're in the deep end and it's iconic) and it's all about write_cgroup_file. Buckle up, it's short but it slays 🎀

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✨ NAME ✨

write_cgroup_file — literally just: write to a cgroup file 🫶

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🌸 SYNOPSIS 🌸

int write_cgroup_file (const char *relative_path , const char *file ,
       const char *buf );

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🦋 ARGUMENTS 🦋

• relative_path — the cgroup path, and yes bestie it's relative to the workdir, don't come at me with absolute paths 💀
• file — the name of the file in cgroupfs you're gonna write to
• buf — the buffer that gets written to the file, that's the whole vibe ✨

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💖 DESCRIPTION 💖

So what it does: it writes to a file in the given cgroup's directory. That's it. That's the whole main character moment 👑

And if it's successful? 0 is returned. Zero. The most beautiful number. No cap 🌈

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🔥 SEE ALSO 🔥

the way this list just keeps going, honestly obsessed:

• Kernel file ./tools/testing/selftests/bpf/cgroup_helpers.c
• enable_controllers(9)
• write_cgroup_file_parent(9)
• setup_cgroup_environment(9)
• join_cgroup(9)
• join_root_cgroup(9)
• join_parent_cgroup(9)
• set_cgroup_xattr(9)
• __cleanup_cgroup_environment(9)
• cleanup_cgroup_environment(9)
• get_root_cgroup(9)
• create_and_get_cgroup(9)
• get_cgroup_id_from_path(9)
• setup_classid_environment(9)
• set_classid(9)
• join_classid(9)
• cleanup_classid_environment(9)
• get_classid_cgroup_id(9)
• get_cgroup1_hierarchy_id(9)
• open_classid(9)

like okay go off, cgroup helper family 👑💅

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ngl if you made it this far you're basically a kernel girlie now. drink some water 💜

and that's the whole page, bestie — sourced from ./tools/testing/selftests/bpf, dated October 2026, mwah 💋🍓