#!/usr/bin/env bash

if [[ $1 -ge 0 && $1 -lt 12 ]]; then
  echo "Good morning!"
elif [[ $1 -ge 12 && $1 -lt 18 ]]; then
  echo "Good afternoon!"
elif [[ $1 -ge 18 && $1 -lt 24 ]]; then
  echo "Good evening!"
else
  echo "Error!"
fi