What is causing the “syntax error near unexpected token `do'” and how can I fix it?

Question

I keep getting this error:

./install.sh 
./install.sh: line 28: syntax error near unexpected token `do'
./install.sh: line 28: `                do'

When running this code (a work in progress):

# Set the prompt string:
PS3='Choose folder: ';

function choose() {

    # This works:
    #select folder;
    #do test -n "$folder" && echo You chose: $REPLY\) $folder && break;
    #echo 'Wrong entry, try again.';
    #continue;
    #done;

    select folder;
    do
        case $folder in
            'q')
                echo 'Exiting …';
                break;
                ;;
            *)
                do
                    test -n '$folder' && echo You chose: $REPLY\) $folder && break;
                    echo 'Wrong entry, try again.';
                    continue;
                done;
                ;;
        esac;
    done;

}

# Switch to glob folder location:
cd ~/Desktop;

# Create menu:
choose foo*;

# Do stuff with result of choose() here ...

# Exit program:
exit 0;

As you can probably see from above, I'm trying to create a menu that lets me choose from a list of globbed folders; unfortunately, I can't figure out why my nested do is creating the error I posted above.

Optimally, the user could choose from a list of directories; if they type q, then the program quits; if they make an invalid selection, the program makes them choose again until they pick a valid selection (or enter q to quit/exit).

I have yet to get the quitting part figured out completely, but before I can do that, I need to get past this do statement error.

Question: What is causing the syntax error near unexpected token `do' and how can I fix it?

Answer 1

Missing Loop Conditional

Your syntax is invalid. You may have other problems with your code as well, but this message is likely coming from the fact that you can't have a do keyword as if it were a block; you need to have one of the loop conditionals as well.

You currently have:

        *)
            do
                test -n '$folder' && echo You chose: $REPLY\) $folder && break;
                echo 'Wrong entry, try again.';
                continue;
            done;
            ;;

You are missing a for, while, or until keyword to start your loop.

Answer 2

In general, when I get that type of error (unmatched if/else, do, while, etc) and I can't find the offending code, I make a backup of the script and start deleting chunks of code between any blocks until I just have a skeleton of control structures and that usually helps me find the missing keyword.