path: root/Doc/library/shutil.rst

:mod:`shutil` --- High-level file operations
============================================

.. module:: shutil
   :synopsis: High-level file operations, including copying.
.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
.. partly based on the docstrings

.. index::
   single: file; copying
   single: copying files

**Source code:** :source:`Lib/shutil.py`

--------------

The :mod:`shutil` module offers a number of high-level operations on files and
collections of files.  In particular, functions are provided  which support file
copying and removal. For operations on individual files, see also the
:mod:`os` module.

.. warning::

   Even the higher-level file copying functions (:func:`shutil.copy`,
   :func:`shutil.copy2`) cannot copy all file metadata.

   On POSIX platforms, this means that file owner and group are lost as well
   as ACLs.  On Mac OS, the resource fork and other metadata are not used.
   This means that resources will be lost and file type and creator codes will
   not be correct. On Windows, file owners, ACLs and alternate data streams
   are not copied.


.. _file-operations:

Directory and files operations
------------------------------

.. function:: copyfileobj(fsrc, fdst[, length])

   Copy the contents of the file-like object *fsrc* to the file-like object *fdst*.
   The integer *length*, if given, is the buffer size. In particular, a negative
   *length* value means to copy the data without looping over the source data in
   chunks; by default the data is read in chunks to avoid uncontrolled memory
   consumption. Note that if the current file position of the *fsrc* object is not
   0, only the contents from the current file position to the end of the file will
   be copied.


.. function:: copyfile(src, dst, symlinks=False)

   Copy the contents (no metadata) of the file named *src* to a file named
   *dst* and return *dst*.  *dst* must be the complete target file name; look at
   :func:`shutil.copy` for a copy that accepts a target directory path.  If
   *src* and *dst* are the same files, :exc:`Error` is raised.

   The destination location must be writable; otherwise,  an :exc:`OSError` exception
   will be raised. If *dst* already exists, it will be replaced.   Special files
   such as character or block devices and pipes cannot be copied with this
   function.  *src* and *dst* are path names given as strings.

   If *symlinks* is true and *src* is a symbolic link, a new symbolic link will
   be created instead of copying the file *src* points to.

   .. versionchanged:: 3.3
      :exc:`IOError` used to be raised instead of :exc:`OSError`.
      Added *symlinks* argument.

   .. versionchanged:: 3.3
      Added return of the *dst*.

.. function:: copymode(src, dst, symlinks=False)

   Copy the permission bits from *src* to *dst*.  The file contents, owner, and
   group are unaffected.  *src* and *dst* are path names given as strings.  If
   *symlinks* is true, *src* a symbolic link and the operating system supports
   modes for symbolic links (for example BSD-based ones), the mode of the link
   will be copied.

   .. versionchanged:: 3.3
      Added *symlinks* argument.

.. function:: copystat(src, dst, symlinks=False)

   Copy the permission bits, last access time, last modification time, and flags
   from *src* to *dst*.  The file contents, owner, and group are unaffected.  *src*
   and *dst* are path names given as strings.  If *src* and *dst* are both
   symbolic links and *symlinks* true, the stats of the link will be copied as
   far as the platform allows.

   .. versionchanged:: 3.3
      Added *symlinks* argument.

.. function:: copy(src, dst, symlinks=False))

   Copy the file *src* to the file or directory *dst* and return the file's
   destination.  If *dst* is a directory, a
   file with the same basename as *src*  is created (or overwritten) in the
   directory specified.  Permission bits are copied.  *src* and *dst* are path
   names given as strings.  If *symlinks* is true, symbolic links won't be
   followed but recreated instead -- this resembles GNU's :program:`cp -P`.

   .. versionchanged:: 3.3
      Added *symlinks* argument.

   .. versionchanged:: 3.3
      Added return of the *dst*.

.. function:: copy2(src, dst, symlinks=False)

   Similar to :func:`shutil.copy`, including that the destination is
   returned, but metadata is copied as well. This is
   similar to the Unix command :program:`cp -p`.  If *symlinks* is true,
   symbolic links won't be followed but recreated instead -- this resembles
   GNU's :program:`cp -P`.

   .. versionchanged:: 3.3
      Added *symlinks* argument, try to copy extended file system attributes
      too (currently Linux only).

   .. versionchanged:: 3.3
      Added return of the *dst*.

.. function:: ignore_patterns(\*patterns)

   This factory function creates a function that can be used as a callable for
   :func:`copytree`\'s *ignore* argument, ignoring files and directories that
   match one of the glob-style *patterns* provided.  See the example below.


.. function:: copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2, ignore_dangling_symlinks=False)

   Recursively copy an entire directory tree rooted at *src*, returning the
   destination directory.  The destination
   directory, named by *dst*, must not already exist; it will be created as
   well as missing parent directories.  Permissions and times of directories
   are copied with :func:`copystat`, individual files are copied using
   :func:`shutil.copy2`.

   If *symlinks* is true, symbolic links in the source tree are represented as
   symbolic links in the new tree and the metadata of the original links will
   be copied as far as the platform allows; if false or omitted, the contents
   and metadata of the linked files are copied to the new tree.

   When *symlinks* is false, if the file pointed by the symlink doesn't
   exist, a exception will be added in the list of errors raised in
   a :exc:`Error` exception at the end of the copy process.
   You can set the optional *ignore_dangling_symlinks* flag to true if you
   want to silence this exception. Notice that this option has no effect
   on platforms that don't support :func:`os.symlink`.

   If *ignore* is given, it must be a callable that will receive as its
   arguments the directory being visited by :func:`copytree`, and a list of its
   contents, as returned by :func:`os.listdir`.  Since :func:`copytree` is
   called recursively, the *ignore* callable will be called once for each
   directory that is copied.  The callable must return a sequence of directory
   and file names relative to the current directory (i.e. a subset of the items
   in its second argument); these names will then be ignored in the copy
   process.  :func:`ignore_patterns` can be used to create such a callable that
   ignores names based on glob-style patterns.

   If exception(s) occur, an :exc:`Error` is raised with a list of reasons.

   If *copy_function* is given, it must be a callable that will be used to copy
   each file. It will be called with the source path and the destination path
   as arguments. By default, :func:`shutil.copy2` is used, but any function
   that supports the same signature (like :func:`shutil.copy`) can be used.

   .. versionchanged:: 3.2
      Added the *copy_function* argument to be able to provide a custom copy
      function.

   .. versionchanged:: 3.2
      Added the *ignore_dangling_symlinks* argument to silent dangling symlinks
      errors when *symlinks* is false.

   .. versionchanged:: 3.3
      Copy metadata when *symlinks* is false.

   .. versionchanged:: 3.3
      Added return of the *dst*.

.. function:: rmtree(path, ignore_errors=False, onerror=None)

   .. index:: single: directory; deleting

   Delete an entire directory tree; *path* must point to a directory (but not a
   symbolic link to a directory).  If *ignore_errors* is true, errors resulting
   from failed removals will be ignored; if false or omitted, such errors are
   handled by calling a handler specified by *onerror* or, if that is omitted,
   they raise an exception.

   .. note::

      On platforms that support the necessary fd-based functions a symlink
      attack resistant version of :func:`rmtree` is used by default. On other
      platforms, the :func:`rmtree` implementation is susceptible to a
      symlink attack: given proper timing and circumstances, attackers can
      manipulate symlinks on the filesystem to delete files they wouldn't
      be able to access otherwise. Applications can use the :data:`rmtree.avoids_symlink_attacks` function attribute to
      determine which case applies.

   If *onerror* is provided, it must be a callable that accepts three
   parameters: *function*, *path*, and *excinfo*.

   The first parameter, *function*, is the function which raised the exception;
   it depends on the platform and implementation.  The second parameter,
   *path*, will be the path name passed to *function*.  The third parameter,
   *excinfo*, will be the exception information returned by
   :func:`sys.exc_info`.  Exceptions raised by *onerror* will not be caught.

   .. versionchanged:: 3.3
      Added a symlink attack resistant version that is used automatically
      if platform supports fd-based functions.

   .. data:: rmtree.avoids_symlink_attacks

      Indicates whether the current platform and implementation provides a
      symlink attack resistant version of :func:`rmtree`. Currently this is
      only true for platforms supporting fd-based directory access functions.

      .. versionadded:: 3.3

.. function:: move(src, dst)

   Recursively move a file or directory (*src*) to another location (*dst*)
   and return the destination.

   If the destination is a directory or a symlink to a directory, then *src* is
   moved inside that directory.

   The destination directory must not already exist.  If the destination already
   exists but is not a directory, it may be overwritten depending on
   :func:`os.rename` semantics.

   If the destination is on the current filesystem, then :func:`os.rename` is
   used.  Otherwise, *src* is copied (using :func:`shutil.copy2`) to *dst* and
   then removed. In case of symlinks, a new symlink pointing to the target of
   *src* will be created in or as *dst* and *src* will be removed.

   .. versionchanged:: 3.3
      Added explicit symlink handling for foreign filesystems, thus adapting
      it to the behavior of GNU's :program:`mv`.

   .. versionchanged:: 3.3
      Added return of the *dst*.

.. function:: disk_usage(path)

   Return disk usage statistics about the given path as a :term:`named tuple`
   with the attributes *total*, *used* and *free*, which are the amount of
   total, used and free space, in bytes.

   .. versionadded:: 3.3

   Availability: Unix, Windows.

.. function:: chown(path, user=None, group=None)

   Change owner *user* and/or *group* of the given *path*.

   *user* can be a system user name or a uid; the same applies to *group*. At
   least one argument is required.

   See also :func:`os.chown`, the underlying function.

   Availability: Unix.

   .. versionadded:: 3.3

.. function:: which(cmd, mode=os.F_OK | os.X_OK, path=None)

   Return the path to an executable which would be run if the given *cmd*
   was called. If no *cmd* would be called, return ``None``.

   *mode* is a permission mask passed a to :func:`os.access`, by default
   determining if the file exists and executable.

   When no *path* is specified, the results of :func:`os.environ` are
   used, returning either the "PATH" value or a fallback of :attr:`os.defpath`.

   On Windows, the current directory is always prepended to the *path*
   whether or not you use the default or provide your own, which
   is the behavior the command shell uses when finding executables.
   Additionaly, when finding the *cmd* in the *path*, the
   ``PATHEXT`` environment variable is checked. For example, if you
   call ``shutil.which("python")``, :func:`which` will search
   ``PATHEXT`` to know that it should look for ``python.exe`` within
   the *path* directories.

      >>> print(shutil.which("python"))
      'c:\\python33\\python.exe'

   .. versionadded:: 3.3

.. exception:: Error

   This exception collects exceptions that are raised during a multi-file
   operation. For :func:`copytree`, the exception argument is a list of 3-tuples
   (*srcname*, *dstname*, *exception*).


.. _shutil-copytree-example:

copytree example
::::::::::::::::

This example is the implementation of the :func:`copytree` function, described
above, with the docstring omitted.  It demonstrates many of the other functions
provided by this module. ::

   def copytree(src, dst, symlinks=False):
       names = os.listdir(src)
       os.makedirs(dst)
       errors = []
       for name in names:
           srcname = os.path.join(src, name)
           dstname = os.path.join(dst, name)
           try:
               if symlinks and os.path.islink(srcname):
                   linkto = os.readlink(srcname)
                   os.symlink(linkto, dstname)
               elif os.path.isdir(srcname):
                   copytree(srcname, dstname, symlinks)
               else:
                   copy2(srcname, dstname)
               # XXX What about devices, sockets etc.?
           except (IOError, os.error) as why:
               errors.append((srcname, dstname, str(why)))
           # catch the Error from the recursive copytree so that we can
           # continue with other files
           except Error as err:
               errors.extend(err.args[0])
       try:
           copystat(src, dst)
       except WindowsError:
           # can't copy file access times on Windows
           pass
       except OSError as why:
           errors.extend((src, dst, str(why)))
       if errors:
           raise Error(errors)

Another example that uses the :func:`ignore_patterns` helper::

   from shutil import copytree, ignore_patterns

   copytree(source, destination, ignore=ignore_patterns('*.pyc', 'tmp*'))

This will copy everything except ``.pyc`` files and files or directories whose
name starts with ``tmp``.

Another example that uses the *ignore* argument to add a logging call::

   from shutil import copytree
   import logging

   def _logpath(path, names):
       logging.info('Working in %s' % path)
       return []   # nothing will be ignored

   copytree(source, destination, ignore=_logpath)


.. _archiving-operations:

Archiving operations
--------------------

High-level utilities to create and read compressed and archived files are also
provided.  They rely on the :mod:`zipfile` and :mod:`tarfile` modules.

.. function:: make_archive(base_name, format, [root_dir, [base_dir, [verbose, [dry_run, [owner, [group, [logger]]]]]]])

   Create an archive file (such as zip or tar) and return its name.

   *base_name* is the name of the file to create, including the path, minus
   any format-specific extension. *format* is the archive format: one of
   "zip", "tar", "bztar" (if the :mod:`bz2` module is available) or "gztar".

   *root_dir* is a directory that will be the root directory of the
   archive; for example, we typically chdir into *root_dir* before creating the
   archive.

   *base_dir* is the directory where we start archiving from;
   i.e. *base_dir* will be the common prefix of all files and
   directories in the archive.

   *root_dir* and *base_dir* both default to the current directory.

   *owner* and *group* are used when creating a tar archive. By default,
   uses the current owner and group.

   *logger* must be an object compatible with :pep:`282`, usually an instance of
   :class:`logging.Logger`.

   .. versionadded:: 3.2


.. function:: get_archive_formats()

   Return a list of supported formats for archiving.
   Each element of the returned sequence is a tuple ``(name, description)``

   By default :mod:`shutil` provides these formats:

   - *gztar*: gzip'ed tar-file
   - *bztar*: bzip2'ed tar-file (if the :mod:`bz2` module is available.)
   - *tar*: uncompressed tar file
   - *zip*: ZIP file

   You can register new formats or provide your own archiver for any existing
   formats, by using :func:`register_archive_format`.

   .. versionadded:: 3.2


.. function:: register_archive_format(name, function, [extra_args, [description]])

   Register an archiver for the format *name*. *function* is a callable that
   will be used to invoke the archiver.

   If given, *extra_args* is a sequence of ``(name, value)`` pairs that will be
   used as extra keywords arguments when the archiver callable is used.

   *description* is used by :func:`get_archive_formats` which returns the
   list of archivers. Defaults to an empty list.

   .. versionadded:: 3.2


.. function:: unregister_archive_format(name)

   Remove the archive format *name* from the list of supported formats.

   .. versionadded:: 3.2


.. function:: unpack_archive(filename[, extract_dir[, format]])

   Unpack an archive. *filename* is the full path of the archive.

   *extract_dir* is the name of the target directory where the archive is
   unpacked. If not provided, the current working directory is used.

   *format* is the archive format: one of "zip", "tar", or "gztar". Or any
   other format registered with :func:`register_unpack_format`. If not
   provided, :func:`unpack_archive` will use the archive file name extension
   and see if an unpacker was registered for that extension. In case none is
   found, a :exc:`ValueError` is raised.

   .. versionadded:: 3.2


.. function:: register_unpack_format(name, extensions, function[, extra_args[, description]])

   Registers an unpack format. *name* is the name of the format and
   *extensions* is a list of extensions corresponding to the format, like
   ``.zip`` for Zip files.

   *function* is the callable that will be used to unpack archives. The
   callable will receive the path of the archive, followed by the directory
   the archive must be extracted to.

   When provided, *extra_args* is a sequence of ``(name, value)`` tuples that
   will be passed as keywords arguments to the callable.

   *description* can be provided to describe the format, and will be returned
   by the :func:`get_unpack_formats` function.

   .. versionadded:: 3.2


.. function:: unregister_unpack_format(name)

   Unregister an unpack format. *name* is the name of the format.

   .. versionadded:: 3.2


.. function:: get_unpack_formats()

   Return a list of all registered formats for unpacking.
   Each element of the returned sequence is a tuple
   ``(name, extensions, description)``.

   By default :mod:`shutil` provides these formats:

   - *gztar*: gzip'ed tar-file
   - *bztar*: bzip2'ed tar-file (if the :mod:`bz2` module is available.)
   - *tar*: uncompressed tar file
   - *zip*: ZIP file

   You can register new formats or provide your own unpacker for any existing
   formats, by using :func:`register_unpack_format`.

   .. versionadded:: 3.2


.. _shutil-archiving-example:

Archiving example
:::::::::::::::::

In this example, we create a gzip'ed tar-file archive containing all files
found in the :file:`.ssh` directory of the user::

    >>> from shutil import make_archive
    >>> import os
    >>> archive_name = os.path.expanduser(os.path.join('~', 'myarchive'))
    >>> root_dir = os.path.expanduser(os.path.join('~', '.ssh'))
    >>> make_archive(archive_name, 'gztar', root_dir)
    '/Users/tarek/myarchive.tar.gz'

The resulting archive contains::

    $ tar -tzvf /Users/tarek/myarchive.tar.gz
    drwx------ tarek/staff       0 2010-02-01 16:23:40 ./
    -rw-r--r-- tarek/staff     609 2008-06-09 13:26:54 ./authorized_keys
    -rwxr-xr-x tarek/staff      65 2008-06-09 13:26:54 ./config
    -rwx------ tarek/staff     668 2008-06-09 13:26:54 ./id_dsa
    -rwxr-xr-x tarek/staff     609 2008-06-09 13:26:54 ./id_dsa.pub
    -rw------- tarek/staff    1675 2008-06-09 13:26:54 ./id_rsa
    -rw-r--r-- tarek/staff     397 2008-06-09 13:26:54 ./id_rsa.pub
    -rw-r--r-- tarek/staff   37192 2010-02-06 18:23:10 ./known_hosts


Querying the size of the output terminal
----------------------------------------

.. versionadded:: 3.3

.. function:: get_terminal_size(fallback=(columns, lines))

   Get the size of the terminal window.

   For each of the two dimensions, the environment variable, ``COLUMNS``
   and ``LINES`` respectively, is checked. If the variable is defined and
   the value is a positive integer, it is used.

   When ``COLUMNS`` or ``LINES`` is not defined, which is the common case,
   the terminal connected to :data:`sys.__stdout__` is queried
   by invoking :func:`os.get_terminal_size`.

   If the terminal size cannot be successfully queried, either because
   the system doesn't support querying, or because we are not
   connected to a terminal, the value given in ``fallback`` parameter
   is used. ``fallback`` defaults to ``(80, 24)`` which is the default
   size used by many terminal emulators.

   The value returned is a named tuple of type :class:`os.terminal_size`.

   See also: The Single UNIX Specification, Version 2,
   `Other Environment Variables`_.

.. _`Other Environment Variables`:
   http://pubs.opengroup.org/onlinepubs/7908799/xbd/envvar.html#tag_002_003