本文共 3045 字，大约阅读时间需要 10 分钟。

转自

http://www.75271.com/1258.html

Python实现文件的全和差异

之前有写利用md5方式来做差异，但是这种md5方式来写存在以下问题：

• md5sum获取有些软连接的MD5值存在问题
• 不支持对空目录进行，因为md5sum无法获取空目录的md5值
• 权限的修改md5sum无法判断

解决方案：

利用文件的mtime ctime

mtime（Modified time）是在写入文件时随文件内容的更改而更改的

ctime（Create time）是在写入文件、更改所有者、权限或链接设置时随Inode的内容更改而更改的

废话不多说直接上代码：

#!/usr/bin/env python 
  import time,os,sys,cPickle 
  fileInfo = {} 
  def logger(time,fileName,status,fileNum): 
      f = open('backup.log','a') 
      f.write("%s\t%s\t%s\t\t%s\n" % (time,fileName,status,fileNum)) 
  def tar(sDir,dDir,fileNum): 
      command = "tar zcf %s %s >/dev/null 2>&1" % (dDir + ".tar.gz",sDir) 
      if os.system(command) == 0: 
          logger(time.strftime('%F %X'),dDir + ".tar.gz",'success',fileNum) 
      else: 
          logger(time.strftime('%F %X'),dDir + ".tar.gz",'failed',fileNum) 
  def fullBak(path): 
      fileNum = 0 
      for root,dirs,files in os.walk(path): 
          for name in files: 
              file = os.path.join(root, name) 
              mtime = os.path.getmtime(file) 
              ctime = os.path.getctime(file) 
              fileInfo[file] = (mtime,ctime) 
              fileNum += 1 
      f = open(P,'w') 
      cPickle.dump(fileInfo,f) 
      f.close() 
      tar(S,D,fileNum) 
  def diffBak(path): 
      for root,dirs,files in os.walk(path): 
          for name in files: 
              file = os.path.join(root,name) 
              mtime = os.path.getmtime(file) 
              ctime = os.path.getctime(file) 
              fileInfo[file] = (mtime,ctime) 
      if os.path.isfile(P) == 0: 
          f = open(P,'w') 
          f.close() 
      if os.stat(P).st_size == 0: 
          f = open(P,'w') 
          cPickle.dump(fileInfo,f) 
          fileNum = len(fileInfo.keys()) 
          f.close() 
          print fileNum 
          tar(S,D,fileNum) 
      else: 
          f = open(P) 
          old_fileInfo = cPickle.load(f) 
          f.close() 
          difference = dict(set(fileInfo.items())^set(old_fileInfo.items())) 
          fileNum = len(difference) 
          print fileNum 
          difference_file = ' '.join(difference.keys()) 
          print difference_file 
          tar(difference_file,D,fileNum) 
          f = open(P,'w') 
          cPickle.dump(fileInfo,f) 
          f.close() 
  def Usage(): 
      print ''' 
          Syntax:  python file_bakcup.py pickle_file model source_dir filename_bk 
              model:  1:Full backup 2:Differential backup 
          example: python file_backup.py fileinfo.pk 2 /etc etc_$(date +%F) 
              explain:  Automatically add '.tar.gz' suffix 
      ''' 
      sys.exit() 
  if len(sys.argv) != 5: 
      Usage() 
  P = sys.argv[1] 
  M = int(sys.argv[2]) 
  S = sys.argv[3] 
  D = sys.argv[4] 
  if M == 1: 
      fullBak(S) 
  elif M == 2: 
      diffBak(S) 
  else: 
      print "\033[;31mDoes not support this mode\033[0m" 
      Usage()

测试使用：

转载地址：http://ompsi.baihongyu.com/