Python中shutil模块的常用文件操作函数用法示例

os模块提供了对目录或者文件的新建/删除/查看文件属性，还提供了对文件以及目录的路径操作。比如说：绝对路径，父目录……  但是，os文件的操作还应该包含移动 复制  打包 压缩 解压等操作，这些os模块都没有提供。
而本文所讲的shutil则就是对os中文件操作的补充。--移动 复制  打包 压缩 解压，
shutil函数功能：
1  shutil.copyfileobj(fsrc,fdst[,length=16*1024])
copy文件内容到另一个文件，可以copy指定大小的内容
先来看看其源代码。

def copyfileobj(fsrc,fdst,length=16*1024):
  """copy data from file-like object fsrc to file-like object fdst"""
  while 1:
    buf = fsrc.read(length)
    if not buf:
      break
    fdst.write(buf)

注意！ 在其中fsrc，fdst都是文件对象，都需要打开后才能进行复制操作

import shutil
f1=open('name','r')
f2=open('name_copy','w+')
shutil.copyfileobj(f1,f2,length=16*1024)

 
2  shutil.copyfile(src,dst)
copy文件内容，是不是感觉上面的文件复制很麻烦？还需要自己手动用open函数打开文件，在这里就不需要了，事实上，copyfile调用了copyfileobj

def copyfile(src,dst,*,follow_symlinks=True):
  if _samefile(src,dst):
    raise SameFileError("{!r} and {!r} are the same file".format(src,dst))
  for fn in [src,dst]:
    try:
      st = os.stat(fn)
    except OSError:
      # File most likely does not exist
      pass
    else:
      # XXX What about other special files? (sockets,devices...)
      if stat.S_ISFIFO(st.st_mode):
        raise SpecialFileError("`%s` is a named pipe" % fn)
  if not follow_symlinks and os.path.islink(src):
    os.symlink(os.readlink(src),dst)
  else:
    with open(src,'rb') as fsrc:
      with open(dst,'wb') as fdst:
        copyfileobj(fsrc,fdst)
  return dst

shutil.copyfile('name','name_copy_2')
#一句就可以实现复制文件内容

3  shutil.copymode(src,dst)  
仅copy权限，不更改文件内容，组和用户。

def copymode(src,follow_symlinks=True):
  if not follow_symlinks and os.path.islink(src) and os.path.islink(dst):
    if hasattr(os,'lchmod'):
      stat_func,chmod_func = os.lstat,os.lchmod
    else:
      return
  elif hasattr(os,'chmod'):
    stat_func,chmod_func = os.stat,os.chmod
  else:
    return
  st = stat_func(src)
  chmod_func(dst,stat.S_IMODE(st.st_mode))

先看两个文件的权限

[root@slyoyo python_test]# ls -l
total 4
-rw-r--r--. 1 root root 79 May 14 05:17 test1
-rwxr-xr-x. 1 root root 0 May 14 19:10 test2

运行命令

>>> import shutil
>>> shutil.copymode('test1','test2')

查看结果

[root@slyoyo python_test]# ls -l
total 4
-rw-r--r--. 1 root root 79 May 14 05:17 test1
-rw-r--r--. 1 root root 0 May 14 19:10 test2

当我们将目标文件换为一个不存在的文件时报错

>>> shutil.copymode('test1','test3')  
Traceback (most recent call last):
 File "<stdin>",line 1,in <module>
 File "/usr/local/python/lib/python3.4/shutil.py",line 132,in copymode
  chmod_func(dst,stat.S_IMODE(st.st_mode))
FileNotFoundError: [Errno 2] No such file or directory: 'test233'

4  shutil.copystat(src,dst)   
复制所有的状态信息，包括权限，组，用户，时间等

def copystat(src,follow_symlinks=True):

  def _nop(*args,ns=None,follow_symlinks=None):
    pass
  # follow symlinks (aka don't not follow symlinks)
  follow = follow_symlinks or not (os.path.islink(src) and os.path.islink(dst))
  if follow:
    # use the real function if it exists
    def lookup(name):
      return getattr(os,name,_nop)
  else:
    # use the real function only if it exists
    # *and* it supports follow_symlinks
    def lookup(name):
      fn = getattr(os,_nop)
      if fn in os.supports_follow_symlinks:
        return fn
      return _nop
  st = lookup("stat")(src,follow_symlinks=follow)
  mode = stat.S_IMODE(st.st_mode)
  lookup("utime")(dst,ns=(st.st_atime_ns,st.st_mtime_ns),follow_symlinks=follow)
  try:
    lookup("chmod")(dst,mode,follow_symlinks=follow)
  except NotImplementedError:
    # if we got a NotImplementedError,it's because
    #  * follow_symlinks=False,#  * lchown() is unavailable,and
    #  * either
    #    * fchownat() is unavailable or
    #    * fchownat() doesn't implement AT_SYMLINK_NOFOLLOW.
    #     (it returned ENOSUP.)
    # therefore we're out of options--we simply cannot chown the
    # symlink. give up,suppress the error.
    # (which is what shutil always did in this circumstance.)
    pass
  if hasattr(st,'st_flags'):
    try:
      lookup("chflags")(dst,st.st_flags,follow_symlinks=follow)
    except OSError as why:
      for err in 'EOPNOTSUPP','ENOTSUP':
        if hasattr(errno,err) and why.errno == getattr(errno,err):
          break
      else:
        raise
  _copyxattr(src,follow_symlinks=follow)

 
5  shutil.copy(src,dst)  
复制文件的内容以及权限，先copyfile后copymode

 def copy(src,follow_symlinks=True):

  if os.path.isdir(dst):
    dst = os.path.join(dst,os.path.basename(src))
  copyfile(src,follow_symlinks=follow_symlinks)
  copymode(src,follow_symlinks=follow_symlinks)
  return dst

6  shutil.copy2(src,dst)   
复制文件的内容以及文件的所有状态信息。先copyfile后copystat

def copy2(src,follow_symlinks=True):
  """Copy data and all stat info ("cp -p src dst"). Return the file's
  destination."
  The destination may be a directory.
  If follow_symlinks is false,symlinks won't be followed. This
  resembles GNU's "cp -P src dst".
  """
  if os.path.isdir(dst):
    dst = os.path.join(dst,follow_symlinks=follow_symlinks)
  copystat(src,follow_symlinks=follow_symlinks)
  return dst

 
7  shutil.copytree(src,symlinks=False,ignore=None,copy_function=copy2,ignore_dangling_symlinks=False)  
递归的复制文件内容及状态信息

def copytree(src,ignore_dangling_symlinks=False):

  names = os.listdir(src)
  if ignore is not None:
    ignored_names = ignore(src,names)
  else:
    ignored_names = set()
  os.makedirs(dst)
  errors = []
  for name in names:
    if name in ignored_names:
      continue
    srcname = os.path.join(src,name)
    dstname = os.path.join(dst,name)
    try:
      if os.path.islink(srcname):
        linkto = os.readlink(srcname)
        if symlinks:
          # We can't just leave it to `copy_function` because legacy
          # code with a custom `copy_function` may rely on copytree
          # doing the right thing.
          os.symlink(linkto,dstname)
          copystat(srcname,dstname,follow_symlinks=not symlinks)
        else:
          # ignore dangling symlink if the flag is on
          if not os.path.exists(linkto) and ignore_dangling_symlinks:
            continue
          # otherwise let the copy occurs. copy2 will raise an error
          if os.path.isdir(srcname):
            copytree(srcname,symlinks,ignore,copy_function)
          else:
            copy_function(srcname,dstname)
      elif os.path.isdir(srcname):
        copytree(srcname,copy_function)
      else:
        # Will raise a SpecialFileError for unsupported file types
        copy_function(srcname,dstname)
    # catch the Error from the recursive copytree so that we can
    # continue with other files
    except Error as err:
      errors.extend(err.args[0])
    except OSError as why:
      errors.append((srcname,str(why)))
  try:
    copystat(src,dst)
  except OSError as why:
    # Copying file access times may fail on Windows
    if getattr(why,'winerror',None) is None:
      errors.append((src,str(why)))
  if errors:
    raise Error(errors)
  return dst
# version vulnerable to race conditions

[root@slyoyo python_test]# tree copytree_test/
copytree_test/
└── test
  ├── test1
  ├── test2
  └── hahaha
[root@slyoyo test]# ls -l
total 0
-rw-r--r--. 1 python python 0 May 14 19:36 hahaha
-rw-r--r--. 1 python python 0 May 14 19:36 test1
-rw-r--r--. 1 root  root  0 May 14 19:36 test2
>>> shutil.copytree('copytree_test','copytree_copy')
'copytree_copy'
[root@slyoyo python_test]# ls -l
total 12
drwxr-xr-x. 3 root  root  4096 May 14 19:36 copytree_copy
drwxr-xr-x. 3 root  root  4096 May 14 19:36 copytree_test
-rw-r--r--. 1 python python  79 May 14 05:17 test1
-rw-r--r--. 1 root  root   0 May 14 19:10 test2
[root@slyoyo python_test]# tree copytree_copy/
copytree_copy/
└── test
  ├── hahaha
  ├── test1
  └── test2

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