$  sudo yum install ruby    # CentOS, Fedora, 或 RHEL 系统
或
sudo apt-get install ruby-full # Debian 或 Ubuntu 系统

$ brew install ruby  #苹果系统

1 puts "Hello, world!"

#!/usr/bin/ruby -w
# -*- coding: UTF-8 -*-

puts "你好，世界！";

class Customer
end

#!/usr/bin/ruby
 
class Customer
   @@no_of_customers=0
   def initialize(id, name, addr)
      @cust_id=id
      @cust_name=name
      @cust_addr=addr
   end
   def display_details()
      puts "Customer id #@cust_id"
      puts "Customer name #@cust_name"
      puts "Customer address #@cust_addr"
    end
    def total_no_of_customers()
       @@no_of_customers += 1
       puts "Total number of customers: #@@no_of_customers"
    end
end