getopts-template.sh

#!/bin/bash

DBG=0

dbg() {
  [[ $DBG == 1 ]] && (1>&2 echo "[DEBUG] : "$1)
}

info() {
  echo "[INFO] : $1"
}

warn() {
  echo "[WARN] : $1"
}

err() {
  (1>&2 echo "[ERROR] : $1")
}

show_help() {
  cat << EOF

  Usage: ${0##*/} -p port [-d] [-h] arg1 arg2 ...argN

  Application description.

  -p port                     Port.
  -d                          Dry run.
  -h                          Print this help.

EOF
}


dry_run=0
port=

while getopts ":p:dh" opt; do

  case $opt in
    p)
      port=$OPTARG
      ;;
    d)
      dry_run=1
      ;;
    h)
      show_help
      exit 0
      ;;
    \?)
      echo >&2
      echo "  Invalid option: -$OPTARG" >&2
      show_help
      exit 1
      ;;
    :)
      echo >&2
      echo "  Option -$OPTARG requires an argument" >&2
      show_help
      exit 2
      ;;
    *)
      show_help
      exit 3
      ;;
  esac

done

shift $((OPTIND-1)) # Shift off the options and optional --

required=(port)

for req in ${required[@]}; do
  [[ -z ${!req} ]] && echo && echo "  Please specify $req" && show_help &&  exit 1
done

echo "Args: $*"

[[ $dry_run -eq 1 ]] && info "Dry run"

[[ $dry_run -eq 0 ]] && echo "Do something with port : $port"