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cpython/Doc/library/shutil.rst
Serhiy Storchaka 2ba095c6c5 Fix shutil.which() test for issue #16993.
2013-01-22 10:32:16 +02:00

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: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, *, follow_symlinks=True)
Copy the contents (no metadata) of the file named *src* to a file named
*dst* and return *dst*. *src* and *dst* are path names given as strings.
*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*
specify the same file, :exc:`SameFileError` 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.
If *follow_symlinks* is false 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 *follow_symlinks* argument.
Now returns *dst*.
.. versionchanged:: 3.4
Raise :exc:`SameFileError` instead of :exc:`Error`. Since the former is
a subclass of the latter, this change is backward compatible.
.. exception:: SameFileError
This exception is raised if source and destination in :func:`copyfile`
are the same file.
.. versionadded:: 3.4
.. function:: copymode(src, dst, *, follow_symlinks=True)
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 *follow_symlinks* is false, and both *src* and *dst* are symbolic links,
:func:`copymode` will attempt to modify the mode of *dst* itself (rather
than the file it points to). This functionality is not available on every
platform; please see :func:`copystat` for more information. If
:func:`copymode` cannot modify symbolic links on the local platform, and it
is asked to do so, it will do nothing and return.
.. versionchanged:: 3.3
Added *follow_symlinks* argument.
.. function:: copystat(src, dst, *, follow_symlinks=True)
Copy the permission bits, last access time, last modification time, and
flags from *src* to *dst*. On Linux, :func:`copystat` also copies the
"extended attributes" where possible. The file contents, owner, and
group are unaffected. *src* and *dst* are path names given as strings.
If *follow_symlinks* is false, and *src* and *dst* both
refer to symbolic links, :func:`copystat` will operate on
the symbolic links themselves rather than the files the
symbolic links refer to--reading the information from the
*src* symbolic link, and writing the information to the
*dst* symbolic link.
.. note::
Not all platforms provide the ability to examine and
modify symbolic links. Python itself can tell you what
functionality is locally available.
* If ``os.chmod in os.supports_follow_symlinks`` is
``True``, :func:`copystat` can modify the permission
bits of a symbolic link.
* If ``os.utime in os.supports_follow_symlinks`` is
``True``, :func:`copystat` can modify the last access
and modification times of a symbolic link.
* If ``os.chflags in os.supports_follow_symlinks`` is
``True``, :func:`copystat` can modify the flags of
a symbolic link. (``os.chflags`` is not available on
all platforms.)
On platforms where some or all of this functionality
is unavailable, when asked to modify a symbolic link,
:func:`copystat` will copy everything it can.
:func:`copystat` never returns failure.
Please see :data:`os.supports_follow_symlinks`
for more information.
.. versionchanged:: 3.3
Added *follow_symlinks* argument and support for Linux extended attributes.
.. function:: copy(src, dst, *, follow_symlinks=True)
Copies the file *src* to the file or directory *dst*. *src* and *dst*
should be strings. If *dst* specifies a directory, the file will be
copied into *dst* using the base filename from *src*. Returns the
path to the newly created file.
If *follow_symlinks* is false, and *src* is a symbolic link,
*dst* will be created as a symbolic link. If *follow_symlinks*
is true and *src* is a symbolic link, *dst* will be a copy of
the file *src* refers to.
:func:`copy` copies the file data and the file's permission
mode (see :func:`os.chmod`). Other metadata, like the
file's creation and modification times, is not preserved.
To preserve all file metadata from the original, use
:func:`~shutil.copy2` instead.
.. versionchanged:: 3.3
Added *follow_symlinks* argument.
Now returns path to the newly created file.
.. function:: copy2(src, dst, *, follow_symlinks=True)
Identical to :func:`~shutil.copy` except that :func:`copy2`
also attempts to preserve all file metadata.
When *follow_symlinks* is false, and *src* is a symbolic
link, :func:`copy2` attempts to copy all metadata from the
*src* symbolic link to the newly-created *dst* symbolic link.
However, this functionality is not available on all platforms.
On platforms where some or all of this functionality is
unavailable, :func:`copy2` will preserve all the metadata
it can; :func:`copy2` never returns failure.
:func:`copy2` uses :func:`copystat` to copy the file metadata.
Please see :func:`copystat` for more information
about platform support for modifying symbolic link metadata.
.. versionchanged:: 3.3
Added *follow_symlinks* argument, try to copy extended
file system attributes too (currently Linux only).
Now returns path to the newly created file.
.. 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:: 3.3
Copy metadata when *symlinks* is false.
Now returns *dst*.
.. versionchanged:: 3.2
Added the *copy_function* argument to be able to provide a custom copy
function.
Added the *ignore_dangling_symlinks* argument to silent dangling symlinks
errors when *symlinks* is false.
.. 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.
.. attribute:: 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`.
Now returns *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. For example, on Windows::
>>> 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 OSError 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 OSError as why:
# can't copy file access times on Windows
if why.winerror is None:
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
--------------------
.. versionadded:: 3.2
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`.
.. 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`.
.. 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.
.. function:: unregister_archive_format(name)
Remove the archive format *name* from the list of supported formats.
.. 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.
.. 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.
.. function:: unregister_unpack_format(name)
Unregister an unpack format. *name* is the name of the format.
.. 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`.
.. _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
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