How to prompt for yes or no in bash?

Question

How do I ask a yes/no type question in Bash?

I ask the question... echo "Do you like pie?"

And receive the answer... read pie

How do I do something if the answer is yes, or starts with y (so yes and yeah, etc, will work too).

Solution 1

I like to use the following function:

function yes_or_no {
    while true; do
        read -p "$* [y/n]: " yn
        case $yn in
            [Yy]*) return 0  ;;  
            [Nn]*) echo "Aborted" ; return  1 ;;
        esac
    done
}

So in your script you can use like this:

yes_or_no "$message" && do_something

In case the user presses any key other than [yYnN] it will repeat the message.

Solution 2

This works too:

read -e -p "Do you like pie? " choice
[[ "$choice" == [Yy]* ]] && echo "doing something" || echo "that was a no"

Pattern starting with Y or y will be taken as yes.

Solution 3

I like Jahid's oneliner. Here is a slight simplification of it:

[[ "$(read -e -p 'Continue? [y/N]> '; echo $REPLY)" == [Yy]* ]]

Here are some tests:

$ [[ "$(read -e -p 'Continue? [y/N]> '; echo $REPLY)" == [Yy]* ]] && echo Continuing || echo Stopping
Continue? [y/N]> yes
Continuing
$ for test_string in y Y yes YES no ''; do echo "Test String: '$test_string'"; echo $test_string | [[ "$(read -e -p 'Continue? [y/N]>'; echo $REPLY)" == [Yy]* ]] && echo Continuing || echo Stopping; done
Test String: 'y'
Continuing
Test String: 'Y'
Continuing
Test String: 'yes'
Continuing
Test String: 'YES'
Continuing
Test String: 'no'
Stopping
Test String: ''
Stopping

Solution 4

This works:

echo "Do you like pie?"
read pie
if [[ $pie == y* ]]; then
    echo "You do! Awesome."
else
    echo "I don't like it much, either."
fi

[[ $pie == y* ]] tests to see of the variable $pie starts with y.

Feel free to make this better if you'd like.

Solution 5

In contrast to the other answers this function gives you the possibility to set a default:

function askYesNo {
        QUESTION=$1
        DEFAULT=$2
        if [ "$DEFAULT" = true ]; then
                OPTIONS="[Y/n]"
                DEFAULT="y"
            else
                OPTIONS="[y/N]"
                DEFAULT="n"
        fi
        read -p "$QUESTION $OPTIONS " -n 1 -s -r INPUT
        INPUT=${INPUT:-${DEFAULT}}
        echo ${INPUT}
        if [[ "$INPUT" =~ ^[yY]$ ]]; then
            ANSWER=true
        else
            ANSWER=false
        fi
}
askYesNo "Do it?" true
DOIT=$ANSWER
if [ "$DOIT" = true ]; then
    < do some stuff >
fi

On the command line you would see

Do it? [Y/n] y

View more solutions

Comments

[Etan Reisner]

read -p "[email protected] [y/n]: " is incorrect, you need to use $* or the read will explode if the function is called with more than one argument. Also, technically this should use yes_or_not "[email protected]" but for this that only matters if you use yes_or_not 'foo bar' and then the user doesn't input yes or no (the inner spaces will then get lost).

[Ben Aubin]

That's pretty awesome :)

[phyatt]

I added a question mark after the $* ... This also works great with an if block: if yes_or_no "Do next task"; then ;;;; fi constructs

[twhitney]

What are the reasons to include the -e and -p flags out of curiosity?

[Jahid]

@twhitney see read --help for details.

[Akhil]

this only works on bash read not zsh read.

[Bruno Bronosky]

@Akhil I added a zsh example for you. ☮️❤️🌈

[Akhil]

appending ? worked for me in zsh. i.e. [[ "$(read -e '?Continue? [y/N]> '; echo $REPLY)" == [Yy]* ]] ref: superuser.com/questions/555874/…