In Bash, why does using getopts in a function only work once? [duplicate]

Answer 1

You have to reset the variable OPTIND, which keeps track of the current positional argument number. It should suffice to make that variable local to your function.

Answer 2

The final code I ended up using:

# Count characters in a string
function cchar() {
    local OPTIND

    while getopts "a:" opt; do
        case $opt in
            a)
                echo ${#OPTARG}
                return
                ;;
        esac
    done

    echo "string is ${#1} characters long"
}

$ cchar "foo bar"
string is 7 characters long

$ cchar -a "foo bar"
7

Note: I had to use return in lieu of exit, when sourced from .bashrc, exit will close the current shell.