BASH script to parse command line arguments

arg-parse.sh

#!/bin/bash

SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
SCRIPT_NAME="arg-parse"
SCRIPT_DES=$'pass in arguments with \e[3m./scripts/arg-parse --arg1 this --arg2 that\e[0m'

function log(){
    echo -e "\e[92m$(date +"%r")\e[0m: \e[4;32m$SCRIPT_NAME\e[0m : >> $1"
}

function help(){
    echo -e "\n\e[4m$SCRIPT_NAME\e[0m\n\n\t$SCRIPT_DES" 
}

while [[ $# -gt 0 ]]; do
 case $1 in
    --arg1)
       ARG1="$2"
       shift
       shift 
       ;;
    --arg2)
       ARG2="$2"
       shift
       shift
       ;;
    --help)
       help
       exit 0
       ;;
    *)
       log "Input not understood. See \e[3m--help\e[0m for information on using this command."
       exit 1
       ;;
  esac
done

log "first arg: $ARG1"
log "second arg: $ARG2"