Bash simple args/options/flags parsing snippet

simple_arg_parse.sh

#!/usr/bin/env bash

parse_args() {
	local foo
	local bar=false

	local positional_args=() # < this line can technically be omitted, if you want to go very minimal
	while [[ $# -gt 0 ]]; do
		case "$1" in
			# CLI Options
			--foo=*) foo="${1#*=}" && shift ;; # Key/value option
			-f | --foo) foo="$2" && shift 2 ;;
			--bar) bar=true && shift ;; # Flag

			# Boilerplate handlers
			--) shift && break ;;                      # Common convention to signal end of opts
			-*) echo "Unknown option: $1" && exit 1 ;; # Error on unknown opt (remove to allow)
			*) positional_args+=("$1") && shift ;;     # Collect positional args
		esac
	done
	set -- "${positional_args[@]}" "$@" && unset positional_args # Restore positional args to $@

	echo -e "--- options ---"
	echo -e "-f, --foo:" "$foo"
	echo -e "--bar:" "$bar"

	echo -e "\n--- positional ---"
	echo -e "$@" "\n"
}

parse_args "$@"

This solution handles most common quick use cases, however, it does not handle:

1. Variable validation (i.e. specific types)
2. Empty variables
3. Duplicate/repeated options (currently will use the value of the last passed option).
4. Anything coming from stdin