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Python中shutil模块的常用文件操作函数用法示例

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Lepaskan: 2016-07-22 08:56:29
asal
2140 orang telah melayarinya

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。

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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)

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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

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import shutil

f1=open('name','r')

f2=open('name_copy','w+')

shutil.copyfileobj(f1,f2,length=16*1024)

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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

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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

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shutil.copyfile('name','name_copy_2')

#一句就可以实现复制文件内容

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

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def copymode(src, dst, *, 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))

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先看两个文件的权限

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[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

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运行命令

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>>> import shutil

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

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查看结果

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[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

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当我们将目标文件换为一个不存在的文件时报错

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>>> 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'

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

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def copystat(src, dst, *, 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, name, _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, dst, follow_symlinks=follow)

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

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def copy(src, dst, *, follow_symlinks=True):

 

 if os.path.isdir(dst):

   dst = os.path.join(dst, os.path.basename(src))

 copyfile(src, dst, follow_symlinks=follow_symlinks)

 copymode(src, dst, follow_symlinks=follow_symlinks)

 return dst

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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

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def copy2(src, dst, *, 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, os.path.basename(src))

  copyfile(src, dst, follow_symlinks=follow_symlinks)

  copystat(src, dst, follow_symlinks=follow_symlinks)

  return dst

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7 shutil.copytree(src, dst, 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

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def copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2,

       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, dstname, symlinks, ignore,

                 copy_function)

          else:

            copy_function(srcname, dstname)

      elif os.path.isdir(srcname):

        copytree(srcname, dstname, symlinks, ignore, 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, dstname, 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, dst, str(why)))

  if errors:

    raise Error(errors)

  return dst

# version vulnerable to race conditions

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[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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8 shutil.rmtree(path, ignore_errors=False, onerror=None)
递归地删除文件

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def rmtree(path, ignore_errors=False, onerror=None):

 

  if ignore_errors:

    def onerror(*args):

      pass

  elif onerror is None:

    def onerror(*args):

      raise

  if _use_fd_functions:

    # While the unsafe rmtree works fine on bytes, the fd based does not.

    if isinstance(path, bytes):

      path = os.fsdecode(path)

    # Note: To guard against symlink races, we use the standard

    # lstat()/open()/fstat() trick.

    try:

      orig_st = os.lstat(path)

    except Exception:

      onerror(os.lstat, path, sys.exc_info())

      return

    try:

      fd = os.open(path, os.O_RDONLY)

    except Exception:

      onerror(os.lstat, path, sys.exc_info())

      return

    try:

      if os.path.samestat(orig_st, os.fstat(fd)):

        _rmtree_safe_fd(fd, path, onerror)

        try:

          os.rmdir(path)

        except OSError:

          onerror(os.rmdir, path, sys.exc_info())

      else:

        try:

          # symlinks to directories are forbidden, see bug #1669

          raise OSError("Cannot call rmtree on a symbolic link")

        except OSError:

          onerror(os.path.islink, path, sys.exc_info())

    finally:

      os.close(fd)

  else:

    return _rmtree_unsafe(path, onerror)

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9 shutil.move(src, dst)
递归的移动文件

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def move(src, dst):

 

  real_dst = dst

  if os.path.isdir(dst):

    if _samefile(src, dst):

      # We might be on a case insensitive filesystem,

      # perform the rename anyway.

      os.rename(src, dst)

      return

    real_dst = os.path.join(dst, _basename(src))

    if os.path.exists(real_dst):

      raise Error("Destination path '%s' already exists" % real_dst)

  try:

    os.rename(src, real_dst)

  except OSError:

    if os.path.islink(src):

      linkto = os.readlink(src)

      os.symlink(linkto, real_dst)

      os.unlink(src)

    elif os.path.isdir(src):

      if _destinsrc(src, dst):

        raise Error("Cannot move a directory '%s' into itself '%s'." % (src, dst))

      copytree(src, real_dst, symlinks=True)

      rmtree(src)

    else:

      copy2(src, real_dst)

      os.unlink(src)

  return real_dst

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10 make_archive(base_name, format, root_dir=None, base_dir=None, verbose=0,dry_run=0, owner=None, group=None, logger=None)

压缩打包

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def make_archive(base_name, format, root_dir=None, base_dir=None, verbose=0,

         dry_run=0, owner=None, group=None, logger=None):

 

  save_cwd = os.getcwd()

  if root_dir is not None:

    if logger is not None:

      logger.debug("changing into '%s'", root_dir)

    base_name = os.path.abspath(base_name)

    if not dry_run:

      os.chdir(root_dir)

  if base_dir is None:

    base_dir = os.curdir

  kwargs = {'dry_run': dry_run, 'logger': logger}

  try:

    format_info = _ARCHIVE_FORMATS[format]

  except KeyError:

    raise ValueError("unknown archive format '%s'" % format)

  func = format_info[0]

  for arg, val in format_info[1]:

    kwargs[arg] = val

  if format != 'zip':

    kwargs['owner'] = owner

    kwargs['group'] = group

  try:

    filename = func(base_name, base_dir, **kwargs)

  finally:

    if root_dir is not None:

      if logger is not None:

        logger.debug("changing back to '%s'", save_cwd)

      os.chdir(save_cwd)

  return filename

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base_name: 压缩打包后的文件名或者路径名
format: 压缩或者打包格式 "zip", "tar", "bztar"or "gztar"
root_dir : 将哪个目录或者文件打包(也就是源文件)

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>>> shutil.make_archive('tarball','gztar',root_dir='copytree_test')

[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 root  root   0 May 14 21:12 tarball.tar.gz

-rw-r--r--. 1 python python  79 May 14 05:17 test1

-rw-r--r--. 1 root  root   0 May 14 19:10 test2

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