bash script for rolling nerdy dice

roll.sh

#!/usr/bin/env bash
# Only supports one die, and the most basic notation right now
# would like to complete support for dice notation as specified here:
# https://en.wikipedia.org/wiki/Dice_notation

_basename() { #portable basename
    [ -z "${1}" ] && return 1 || _basename__name="${1%%/}"
    [ -z "${2}" ] || _basename__suffix="${2}"
    case "${_basename__name}" in
        /*|*/*) _basename__name="$(expr "${_basename__name}" : '.*/\([^/]*\)')" ;;
    esac

    if [ -n "${_basename__suffix}" ] && [ "${#_basename__name}" -gt "${#2}" ]; then
        if [ X"$(printf "%s" "${_basename__name}" | cut -c"$((${#_basename__name} - ${#_basename__suffix} + 1))"-"${#_basename__name}")" \
           = X"$(printf "%s" "${_basename__suffix}")" ]; then
            _basename__name="$(printf "%s" "${_basename__name}" | cut -c1-"$((${#_basename__name} - ${#_basename__suffix}))")"
        fi
    fi

    printf "%s" "${_basename__name}"
}

_random() { #return a random number between two limits
    #default to numbers between 1-10
    local _min="${1:-1}"
    local _max="${2:-10}"
    local diff=$((${_max}-${_min}+1))
    echo -n "$(($((${RANDOM}%${diff}))+${_min}))"
}

if [ $# -lt 1 ]; then
  echo "USAGE: $(_basename $0) [number of dice]d[sides of dice] (i.e. 1d6)"
  exit 1
fi

NOTATION="$1"
QTY="${NOTATION%%d*}"
NUMBER_OF_SIDES="${NOTATION#*d}"

TOTAL=0
for i in $(seq 1 $QTY); do
  result="$(_random 1 ${NUMBER_OF_SIDES})"
  echo -n "$result"
  if [[ i -lt $QTY ]]; then
    echo -n ", "
  fi
  TOTAL=$((TOTAL+${result}))
done

if [ ${QTY} -gt 1 ]; then
  echo " = ${TOTAL}"
else
  echo
fi