Simple script to list all parents from a given pid

parent-pid-tree.sh

#!/bin/bash
[ $# -lt 1 ] && {
    echo 'inform the pid' >&2
    exit 1
}
pid=$1
while true
do
    ps -o pid,cmd -p $pid
    [ $pid -eq 1 ] && break
    pid=$(ps -o ppid -p $pid | tail -n1)
done