read input from user in while loop having input and output redirection

Question

This is my code:

while IFS=',' read a b c; do
     read input
     echo $input
done 3<&0 < input.csv > output.txt

I took care of input redirection by redirecting through pipeline. But still,when I run the above code, control does not stop for input.

Why?

Answer 1

It's because your input stream is feeding both read. You're almost right, so maybe it's a typo (you just forgot to give to right FD to your second read) :

while IFS=',' read a b c; do
  read input <&3
  echo $input
done 3<&0 < input.csv >> output.txt