getppid.sh

function getPPID() {
        _pid0=$1
        _pid=`ps --no-header -o pid -p $_pid0`
        if [ "x$_pid" == "x" ]
        then
                echo "Error: $_pid0 does not exists"
                return
        fi
        echo -n "$_pid > "
        _ppid=`ps --no-header -o ppid -p $_pid`

        if [ "x$_ppid" == "x" ] || [ $_ppid -le 1 ]
        then
                echo $_ppid
                return
        fi

        getPPID $_ppid
}

getPPID $1
echo