近来用盛大云存储备份本地数据文件，每日同步。盛大云有个python命令行工具，里边的sync命令可以很便捷的把本地新增的备份文件同步到云端。但本地已删除的备份文件云端并不会同步删除。以下这个脚本是用来清除本地已不存在而云端尚存的旧文件。

snda-clean.rb

#!/usr/bin/env ruby
require 'rubygems'
require 'pp'
require 'sndacs'
SRC= '/home/backup/db/' 
BUCKET= 'muzik_backup'
CONFIG ={
  :access_key_id => '**',
  :secret_access_key => '**'
}
def copy_dir dir,bucket
  Dir.foreach dir do |d|
    next if %(. ..).include? d
    realpath = "#{dir}/#{d}"
    if File.directory?(realpath)
      copy_dir realpath,bucket
    else
      copy_file realpath,bucket
    end
  end
end
def clean_dir dir,bucket
  files =  `find #{dir} -type f`.split("\n").collect{|r| relative_filename r}
  files +=  `find #{dir} -type d`.split("\n").collect{|r| "#{relative_filename r}/"}
  #pp files
  bucket.objects.each do |o|
    next if files.include? o.key
    o.destroy
  end
end
def copy_file file,bucket
  relpath = relative_filename file
  object = (bucket.objects.find relpath rescue nil)

  file_data = File.read(file)
  unless object.nil?
    if Digest::MD5.hexdigest(file_data) == object.etag
      #pp "#{relpath} exists"
      return
    end
  end
  object = bucket.objects.build relpath
  object.content = file_data
  object.save
end
def relative_filename path
  path.sub(SRC,'').sub(/^\//,'')
end
api = Sndacs::Service.new CONFIG
bucket = api.buckets.find BUCKET

#copy_dir SRC,bucket
clean_dir SRC,bucket