get_cgroup1_hierarchy_id(9)

💅 get_cgroup1_hierarchy_id(9) — a Kernel API Manual moment

okay so bestie, welcome to the <pink>get_cgroup1_hierarchy_id</pink> page, straight outta the Kernel API Manual. this one's a lil function that does exactly one thing and does it cute. let's get into it 🎀

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✨ NAME ✨

get_cgroup1_hierarchy_id — gets you the ID of a cgroup1 hierarchy, and it pulls it straight from the cgroup1 subsys name. that's it, that's the whole vibe. 💖

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🌸 SYNOPSIS 🌸

int get_cgroup1_hierarchy_id (const char *subsys_name );

literally one argument, one int back. she's low maintenance, we stan. ✨

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🦋 ARGUMENTS 🦋

• subsys_name — the cgroup1 subsys name, and ngl you can grab this from /proc/self/cgroup. it can be a named cgroup like "name=systemd", or a controller name like "net_cls", or even multi-controllers like "net_cls,net_prio". so she's flexible, she's versatile, she contains multitudes 💅

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👑 SEE ALSO 👑

like, go look at this kernel file, it's right there in the source:

• Kernel file ./tools/testing/selftests/bpf/cgroup_helpers.c

and the whole friend group of related functions, no cap:

• enable_controllers(9)
• write_cgroup_file(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)
• open_classid(9)

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fr fr, that's the whole page — no hidden options, no secret environment variables, no exit statuses hiding in the bushes. just subsys_name in, hierarchy ID out. 🫶

and that's a wrap bestie!! this icon was brought to you by the <purple>./tools/testing/selftests/bpf</purple> section (iykyk), dated `October 2026. mwah, go read your kernel source, ily 💜🧚⭐