Question

I have a bash script which is getting options (using getopts). Let say they are ‘-n’ , ‘-d’ , ‘-u’ . I only want to have one of the option being chosen, if not, it will prompt the user error.

The code is like this:

    while getopts ":dun" name; do

            case $name in

              d  )
                    DELETE='YES'
                    ;;
              u  )
                    UPDATE='YES'
                    ;;
              n  )
                    NEW='YES'
                    ;;
            esac
     done

I can only have $DELETE or $UPDATE or $NEW being ‘YES’ in one time, meaning the user cannot specific ‘-n’ and ‘-d’ in the same time or ‘-u’ and ‘-n’ in the same time, how do I achieve that in a IF statement ?

I have been looking for this in stackoverflow, but can’t find any. Thanks for the help, mate!

Answer 1

This is a complete hack, and depends on the option variables being either unset or “YES” (and in the form I’ve written it, is bash-only):

if [[ "$DELETE$UPDATE$NEW" == YESYES* ]]; then
    echo "Please only use one of -d, -u, and -n" >&2
    exit 1
fi

(If you were using the brand-x shell instead of bash, it’d be something like if [ "$DELETE$UPDATE$NEW" = "YESYES" -o "$DELETE$UPDATE$NEW" = "YESYESYES" ]; then)