#!/bin/bash

PPID=`ps -o ppid -p $$`

echo parent PID $PPID

PTTY=`ps -p $PPID -o tty --no-headers`

echo parent TTY $PTTY 

while IFS= read -r line; do
	echo "read one line";
done

while IFS= read -r line; do
	echo "read one line 2";
done < /dev/$PTTY