Optional option argument with getopts

Question

while getopts "hd:R:" arg; do
  case $arg in
    h)
      echo "usage" 
      ;;
    d)
      dir=$OPTARG
      ;;
    R)
      if [[ $OPTARG =~ ^[0-9]+$ ]];then
        level=$OPTARG
      else
        level=1
      fi
      ;;
    \?)
      echo "WRONG" >&2
      ;;
  esac
done

• level refers to the parameter of -R, dir refers to parameters of -d

• when I input ./count.sh -R 1 -d test/ it works correctly

• when I input ./count.sh -d test/ -R 1 it works correctly

• but I want to have it work when I input ./count.sh -d test/ -R or ./count.sh -R -d test/

This means that I want -R to have a default value and for the sequence of commands to be more flexible.

Answer 1

getopts doesn't really support this; but it's not hard to write your own replacement.

while true; do
    case $1 in
      -R) level=1
            shift
            case $1 in
              *[!0-9]* | "") ;;
              *) level=$1; shift ;;
            esac ;;
        # ... Other options ...
        -*) echo "$0: Unrecognized option $1" >&2
            exit 2;;
        *) break ;;
    esac
done