Search notes:

/proc/$pid/cpuset

/proc/$pid/cpuset displays the path of the process's cpuset directory relative to the root of the cpuset filesystem.

TODO

According to this Stackoverflow answer, the container ID of a docker container can be determined from within the container with the following command: 
$ basename $(cat /proc/1/cpuset)

See also

See man 7 cpuset and Documentation/admin-guide/cgroup-v1/cpusets.rst in the Linux kernel sources.
/proc/$pid

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