In Bash, how to add “Are you sure [Y/n]” to any command or alias?

Question

In this particular case, I\'d like to add a confirm in Bash for

Are you sure? [Y/n]

for Mercurial\'s hg push ssh://username@www.example.com//some

Answer 1

This version allows you to have more than one case y or Y, n or N

1. Optionally: Repeat the question until an approve question is provided

2. Optionally: Ignore any other answer

3. Optionally: Exit the terminal if you want

   confirm() {
       echo -n "Continue? y or n? "
       read REPLY
       case $REPLY in
       [Yy]) echo 'yup y' ;; # you can change what you do here for instance
       [Nn]) break ;;        # exit case statement gracefully
       # Here are a few optional options to choose between
       # Any other answer:
   
       # 1. Repeat the question
       *) confirm ;;
   
       # 2. ignore
       # *) ;;
   
       # 3. Exit terminal
       # *) exit ;;
   
       esac
       # REPLY=''
   }
   

Notice this too: On the last line of this function clear the REPLY variable. Otherwise if you echo $REPLY you will see it is still set until you open or close your terminal or set it again.