Shell. Ограничить ввод read

#!bin/bash
cat $1 | grep regexp |
while read line
do
        echo $line
done

$ while true
do 
 echo 'enter shit'
 read line
 echo $line | egrep -q 'shit' && break
done; echo "yes its $line"
enter shit
123
enter shit
df
enter shit
kg
enter shit
shit
yes its shit