监控服务器存活的脚本，用ruby写的，需要安装有action_mailer gem,

在前面的日志中有说明怎样连接gmail来发送邮件的

require 'rubygems'
require 'action_mailer'
require 'ping'
require 'fileutils'
require 'tlsmail' #need install tlsmail gem to support TLS connect
Net::SMTP.enable_tls(OpenSSL::SSL::VERIFY_NONE)

#发送通知from账户设置
ActionMailer::Base.smtp_settings = {
  :address => 'smtp.gmail.com',
  :port => '25',
  :domain => 'gmail.com',
  :user_name => 'username',
  :password => 'passwd',
  :authentication => :login
}

#recp: 收到通知的邮箱地址，可以填多个地址，逗号分隔
#sub: 邮件主题
#bo: 邮件内容
class SimpleMailer < ActionMailer::Base
  def simple_message(recp, sub, bo)
    from 'sender@gmail.com'
    recipients recp
    subject sub
    body bo
  end
end

class ServerMonitor
  def initialize
    #config
    @hit = 5  #最大失败次数，达到后才会发送邮件，避免误报
    @tmp = "/tmp/server_monitor_tmp"  #计数器地址
    @recp = 'mytake6@gmail.com, std8545@yahoo.com.cn'  #收信的邮箱地址
    @host = ['www.ccok.me', 'www.google.com']  #需要监控的主机
    
    #do not touch these
    @hosts = Struct.new(:host, :status)
    @servers, @msg = [], []
    @host.each { |h| @servers << @hosts.new(h, true) }
    
    FileUtils.mkdir(@tmp) unless File.exists? @tmp
  end
  
  def run
    @servers.each do |s| 
      num = Ping.pingecho(s.host, 5, 80) ? 0 : rf(s.host) + 1
      File.open(dest(s.host), 'w') { |f| f.puts num }
    end

    @servers.each do |e|
      if rf(e.host) == @hit
        e.status = false
        File.open(dest(e.host), 'w') { |f| f.puts 0 }
      end
    end
    
    send_mail
  end
  
  def rf file
    return 0 unless File.exist?(dest(file))
    File.open(dest(file), 'r').readlines.to_s.chomp.to_i
  end
  
  def dest host
    "#{@tmp}/#{host}"
  end
  
  def send_mail
    @servers.each { |m| @msg << m.host unless m.status }
    SimpleMailer.deliver_simple_message @recp, 
        "server monitor", 
        @msg.join(', ') + " is Down!!! " unless @msg.empty?
  end
end

#go
ServerMonitor.new.run

可以放到crontab中每2分钟运行一次