bash cli with positional and named arguments

cli.sh

#!/bin/bash
set -o errexit

force=false
reg_name='test'
reg_port='5001'
pos_args=()

while [ $# -gt 0 ]; do
    arg="$1"
    if [[ ${arg:0:1} != "-" ]]; then
        # handle positional argument
        pos_args+=("$arg")
    else
        case $arg in
            -h|--help)
                echo "options:"
                echo "-h, --help      show brief help"
                echo "-f, --force     to force recreate cluster"
                echo "-rn, --regname  registry name"
                echo "-rp, --regport  registry port"
                exit 0
                ;;
            -f|--force)
                force=true
                ;;
            -rn|--regname)
                reg_name=$2
                shift
                ;;
            -rp|--regport)
                reg_port=$2
                shift
                ;;
            *)
                echo "Unknown option: $arg"
                exit 1
                ;;
        esac
    fi
    shift
done