bash Cookbook

Selecting from a List of Options

Problem

You need to provide the user with a list of options to choose from and you don’t want to make them type any more than necessary.

Solution

Use bash’s built-in select construct to generate a menu, then have the user choose by typing the number of the selection:

# cookbook filename: select_dir

directorylist="Finished $(for i in /*;do [ -d "$i" ] && echo $i; done)"

PS3='Directory to process? ' # Set a useful select prompt
until [ "$directory" == "Finished" ]; do

    printf "%b" "\a\n\nSelect a directory to process:\n" >&2
    select directory in $directorylist; do

        # User types a number which is stored in $REPLY, but select
        # returns the value of the entry
        if [ "$directory" == "Finished" ]; then
            echo "Finished processing directories."
            break
        elif [ -n "$directory" ]; then
            echo "You chose number $REPLY, processing $directory..."
            # Do something here
            break
        else
            echo "Invalid selection!"
        fi # end of handle user's selection

    done # end of select a directory
done # end of until dir == finished

Discussion

The select function makes it trivial to present a numbered list to the user on STDERR, from which they may make a choice. Don’t forget to provide an “exit” or “finished” choice.

The number the user typed is returned in $REPLY, and the value of that entry is returned in the variable you specified in the select construct.

See Also

• help select

• help read

• Getting Yes or No Input