Shell Programming and Scripting

#cat test.txt
first line
second line
third line
#cat test.sh
#!/bin/ksh
read_write () {
echo "Do you want to print the line (YES/NO)?\n"

read TEST
case ${TEST} in
        YES) return 0;;
        NO) return 1;;
        *) read_write;;
esac
}

while read _line 
do
        read_write
done < ./test.txt

#test.sh
Do you want to print the line (YES/NO)?

[...]

Do you want to print the line (YES/NO)?

./test.sh[7]: read_write: recursion too deep

read_write () 
{
echo -n "Do you want to print the line (Y/N)?"
<&5 read  TEST   # input from handler 5 = org. stdin
case "$TEST" in
        Y) return 0;;
        N) return 1;;
        *) read_write;;
esac
}

exec 4< ./test.txt  # handler 4 for file
exec 5<&1    # handler 5 is same as stdin handler 1
while read line   
do
        echo $line      # stdout
        read_write
done <&4