利用python备份文件夹

以前写过一个非常白痴的备份脚本，就是将着整个我文件夹都拷贝到u盘里，每次拷贝前都将已经存在的文件夹删除掉。这样的话程序就很傻瓜代码也很少

1 import os
2 
3 def backup(from_path,to_path):
4     if os.path.exists(to_path):
5         os.system('rm -rf to_path')
6     os.system('cp from_path to_path')

今天在python cookbook上看到一段代码，这段代码也是利用python进行备份文件夹，但是它的程序要聪明一点，只拷贝那些还未被备份的文件

 1 import os,sys,shutil,filecmp
 2 
 3 #def backup(path,backdirname = 'back'):
 4 #    for dir,subdir,files in os.walk(path):
 5 #        if backdirname not in subdir:
 6 #            backdir = os.path.join(dir,backdirname)
 7 #            os.mkdir(backdir)
 8 #        subdir[:] = [d for d in subdir if d !=backname]
 9 #        for file in files:
10 #            filepath = os.path.join(dir,file)
11 #            for index in xrange(100):
12 #                backfile = '%s.%2.2%d'%(file,index)
13 #                backpath = os.path.join(dir,backfile)
14 #                if os.path.exists(backpath):break
15 #            if index>0:
16 #                old_backpath
17 
18 def backup(path,backdir_name='backdir'):
19     MAXVERSIONS = 100
20     for dir,subdir,files in os.walk(path):
21         backdir = os.path.join(dir,backdir_name)
22         if not os.path.exists(backdir):
23             os.mkdir(backdir)
24 
25         subdir[:] = [d for d in subdir if d != backdir_name]
26         for file in files:
27             filepath = os.path.join(dir,file)
28             backpath = os.path.join(backdir,file)
29 
30             for index in xrange(MAXVERSIONS):
31                 backfile_name = '%s.%2.2d'%(backpath,index)
32                 if not os.path.exists(backfile_name):break
33 
34 
35             if index>0:
36                 old_backup = '%s.%2.2d'%(backpath,index-1)
37                 abspath = os.path.abspath(filepath)
38                 try:
39                     if os.path.isfile(abspath) and filecmp.cmp(old_backup,abspath,shallow = False):
40                         continue
41                 except OSError:
42                     pass
43                 
44             try:
45                 shutil.copy(filepath,backfile_name)
46             except OSError:
47                 pass
48 if __name__ == '__main__':
49     path = raw_input('please input the backup dir:')
50     backup(path)