#!/bin/bash
ps_parents () 
{ 
    if [ "$#" -ne 1 ]; then
        echo "Usage: $0 <pid>";
        return 1;
    fi;
    pid=$1;
    while [ "$pid" -ne 1 ]; do
        ps -p $pid -o pid=,ppid=,cmd=;
        pid=$(ps -p $pid -o ppid= --no-headers);
    done
}
ps_parents "$@"