A better usage of Bash's getopt or getop which can handle = properly

getopt_better_example.sh

#!/bin/bash
set -e
USAGE="$(basename "$0") -a [ARGUMENT A] --b [ARGUMENT_B] [-c [ARGUMENT_C]] -- Creates a docker tag from supplied info

where:
    -a|--arga  The first argument, A
    -b|--argb  The second argument, B
    -c|--argc  The third argument, C
"

ARGS=("$@")

# read the options
while [[ "${#ARGS[@]}" -gt 0 ]]; do
    KEY="${ARGS[0]}"
    VALUE="${ARGS[1]}"

    case "${KEY}" in
        -a|--arga)
            ARG_A="$VALUE"
            ARGS=("${ARGS[@]:2}")
            ;;
        -b|--argb)
            ARG_B="$VALUE"
            ARGS=("${ARGS[@]:2}")
            ;;
        -c|--argc)
            ARG_C="$VALUE"
            ARGS=("${ARGS[@]:2}")
            ;;
        -h|--help)
            echo "${USAGE}" >&2
            exit 0
            ;;
        *)  # Unknown Option or "key=value"
            while IFS='=' read -ra SPLIT <<< ${KEY}; do
                # Split by the "=" and add back to our arguments array
                for i in "${SPLIT[@]}"; do
                  ARGS+=("${i}")
                done
                FOUND_SPLIT=1
                ARGS=("${ARGS[@]:1}")
                break
            done
            if [[ -z "${FOUND_SPLIT}" ]]; then
                echo "Unknown option $1"
                echo "${USAGE}"
                exit 1
            fi
            ;;
        --)
            ARGS=("${ARGS[@]:1}")
            break
            ;;
    esac
done

echo "ARG_A: ${ARG_A}"
echo "ARG_B: ${ARG_B}"
echo "ARG_C: ${ARG_C}"

# Test cases:
# ./getopt_better_example.sh -a hello --argb "world --argc="it works"