Check if the current process has a given ancestor by name

has-ancestrol-process.bash

#!/bin/bash

# works on plain vanillla OS X 10.11.4 without installing pstree, 
# which is of course the sane way to do this

if [ "$#" -ne 1 ]; then
    echo "usage: $0 key" 1>&2
    echo "$0 finishes with an exit code of 0 if key was found in ancestral process; 1 if not; 2, if it is showing this usage message" 1>&2
    exit 2
fi

key="$1"

function join { local IFS="$1"; shift; echo "$*"; }

function parentProcess() {
    ps -p "$1" -o ppid=
}

foundPids=()
currentPid="$$"

while [ $(parentProcess "$currentPid") != "0" ]; do
    foundPids+="      $(parentProcess  "$currentPid")     "
    currentPid=$(parentProcess  "$currentPid")
done

exec fgrep "$key" <(ps -p "$(join , "$foundPids")") >/dev/null 2>/dev/null