Matching "y", "Yes", "YES" or "yes" case-insensitively in bash

Question

I have an if/then statement prompting for user input:

if [[ "$email_answer" = [Yy] ]]; then

How do I get that statement to accept the word "Yes", "YES" or "yes" in addition to "Y" or "y"?

Answer 1

You can use case for this:

case $email_answer in
  [yY][eE][sS]|[yY])
  ;;
esac