Stuff like https://github.com/p8952/bocker/blob/master/bocker#L94 is super dense.

I might write that something like:

    cid="$(
      ps o ppid,pid |
        grep "^$(
          ps o pid,cmd |
            grep -E "^\ *[0-9]+ unshare.*$1" |
            awk '{print $1}'
        )" |
        awk '{print $2}'
    )"