Catatonit is a /sbin/init program for use within containers. It
forwards (almost) all signals to the spawned child, tears down
the container when the spawned child exits, and otherwise
cleans up other exited processes (zombies).
This is a reimplementation of other container init programs (such as
"tini" or "dumb-init"), but uses modern Linux facilities (such as
signalfd(2)) and has no additional features.