10.10. "shutil" — High-level file operations
********************************************

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

======================================================================

The "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 "os" module.

警告: Even the higher-level file copying functions ("shutil.copy()",
  "shutil.copy2()") can’t 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.


10.10.1. Directory and files operations
=======================================

shutil.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.

shutil.copyfile(src, dst)

   Copy the contents (no metadata) of the file named *src* to a file
   named *dst*.  *dst* must be the complete target file name; look at
   "shutil.copy()" for a copy that accepts a target directory path.
   If *src* and *dst* are the same files, "Error" is raised. The
   destination location must be writable; otherwise,  an "IOError"
   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.

shutil.copymode(src, dst)

   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.

shutil.copystat(src, dst)

   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.

shutil.copy(src, dst)

   Copy the file *src* to the file or directory *dst*.  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.

shutil.copy2(src, dst)

   Identical to "copy()" except that "copy2()" also attempts to
   preserve file metadata.

   "copy2()" uses "copystat()" to copy the file metadata. Please see
   "copystat()" for more information.

shutil.ignore_patterns(*patterns)

   This factory function creates a function that can be used as a
   callable for "copytree()"’s *ignore* argument, ignoring files and
   directories that match one of the glob-style *patterns* provided.
   See the example below.

   2.6 新版功能.

shutil.copytree(src, dst, symlinks=False, ignore=None)

   Recursively copy an entire directory tree rooted at *src*.  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 "copystat()", individual
   files are copied using "shutil.copy2()".

   If *symlinks* is true, symbolic links in the source tree are
   represented as symbolic links in the new tree, but the metadata of
   the original links is NOT copied; if false or omitted, the contents
   and metadata of the linked files are copied to the new tree.

   If *ignore* is given, it must be a callable that will receive as
   its arguments the directory being visited by "copytree()", and a
   list of its contents, as returned by "os.listdir()".  Since
   "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.
   "ignore_patterns()" can be used to create such a callable that
   ignores names based on glob-style patterns.

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

   The source code for this should be considered an example rather
   than the ultimate tool.

   在 2.3 版更改: "Error" is raised if any exceptions occur during
   copying, rather than printing a message.

   在 2.5 版更改: Create intermediate directories needed to create
   *dst*, rather than raising an error. Copy permissions and times of
   directories using "copystat()".

   在 2.6 版更改: Added the *ignore* argument to be able to influence
   what is being copied.

shutil.rmtree(path[, ignore_errors[, onerror]])

   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.

   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 will be
   "os.path.islink()", "os.listdir()", "os.remove()" or "os.rmdir()".
   The second parameter, *path*, will be the path name passed to
   *function*.  The third parameter, *excinfo*, will be the exception
   information return by "sys.exc_info()".  Exceptions raised by
   *onerror* will not be caught.

   在 2.6 版更改: Explicitly check for *path* being a symbolic link
   and raise "OSError" in that case.

shutil.move(src, dst)

   Recursively move a file or directory (*src*) to another location
   (*dst*).

   If the destination is an existing directory, then *src* is moved
   inside that directory. If the destination already exists but is not
   a directory, it may be overwritten depending on "os.rename()"
   semantics.

   If the destination is on the current filesystem, then "os.rename()"
   is used.  Otherwise, *src* is copied (using "shutil.copy2()") to
   *dst* and then removed.

   2.3 新版功能.

exception shutil.Error

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

   2.3 新版功能.


10.10.1.1. copytree example
---------------------------

This example is the implementation of the "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, ignore=None):
       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 symlinks and os.path.islink(srcname):
                   linkto = os.readlink(srcname)
                   os.symlink(linkto, dstname)
               elif os.path.isdir(srcname):
                   copytree(srcname, dstname, symlinks, ignore)
               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 "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)


10.10.2. Archiving operations
=============================

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

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

   Create an archive file (eg. zip or tar) and returns 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” (if the "zlib" module or external "zip"
   executable is available), “tar”, “gztar” (if the "zlib" module is
   available), or “bztar” (if the "bz2" module is available).

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

   *base_dir* is the directory where we start archiving from; ie.
   *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 "logging.Logger".

   2.7 新版功能.

shutil.get_archive_formats()

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

   By default "shutil" provides these formats:

   * *zip*: ZIP file (if the "zlib" module or external "zip"
     executable is available).

   * *tar*: uncompressed tar file.

   * *gztar*: gzip’ed tar-file (if the "zlib" module is available).

   * *bztar*: bzip2’ed tar-file (if the "bz2" module is available).

   You can register new formats or provide your own archiver for any
   existing formats, by using "register_archive_format()".

   2.7 新版功能.

shutil.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)" that will
   be used as extra keywords arguments when the archiver callable is
   used.

   *description* is used by "get_archive_formats()" which returns the
   list of archivers. Defaults to an empty list.

   2.7 新版功能.

shutil.unregister_archive_format(name)

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

   2.7 新版功能.


10.10.2.1. Archiving example
----------------------------

In this example, we create a gzip’ed tar-file archive containing all
files found in the ".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
