cpython/Doc/library/filecmp.rst
2007-08-15 14:28:22 +00:00

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:mod:`filecmp` --- File and Directory Comparisons
=================================================
.. module:: filecmp
:synopsis: Compare files efficiently.
.. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>
The :mod:`filecmp` module defines functions to compare files and directories,
with various optional time/correctness trade-offs.
The :mod:`filecmp` module defines the following functions:
.. function:: cmp(f1, f2[, shallow])
Compare the files named *f1* and *f2*, returning ``True`` if they seem equal,
``False`` otherwise.
Unless *shallow* is given and is false, files with identical :func:`os.stat`
signatures are taken to be equal.
Files that were compared using this function will not be compared again unless
their :func:`os.stat` signature changes.
Note that no external programs are called from this function, giving it
portability and efficiency.
.. function:: cmpfiles(dir1, dir2, common[, shallow])
Returns three lists of file names: *match*, *mismatch*, *errors*. *match*
contains the list of files match in both directories, *mismatch* includes the
names of those that don't, and *errros* lists the names of files which could not
be compared. Files may be listed in *errors* because the user may lack
permission to read them or many other reasons, but always that the comparison
could not be done for some reason.
The *common* parameter is a list of file names found in both directories. The
*shallow* parameter has the same meaning and default value as for
:func:`filecmp.cmp`.
Example::
>>> import filecmp
>>> filecmp.cmp('undoc.rst', 'undoc.rst')
True
>>> filecmp.cmp('undoc.rst', 'index.rst')
False
.. _dircmp-objects:
The :class:`dircmp` class
-------------------------
:class:`dircmp` instances are built using this constructor:
.. class:: dircmp(a, b[, ignore[, hide]])
Construct a new directory comparison object, to compare the directories *a* and
*b*. *ignore* is a list of names to ignore, and defaults to ``['RCS', 'CVS',
'tags']``. *hide* is a list of names to hide, and defaults to ``[os.curdir,
os.pardir]``.
The :class:`dircmp` class provides the following methods:
.. method:: dircmp.report()
Print (to ``sys.stdout``) a comparison between *a* and *b*.
.. method:: dircmp.report_partial_closure()
Print a comparison between *a* and *b* and common immediate subdirectories.
.. method:: dircmp.report_full_closure()
Print a comparison between *a* and *b* and common subdirectories (recursively).
The :class:`dircmp` offers a number of interesting attributes that may be used
to get various bits of information about the directory trees being compared.
Note that via :meth:`__getattr__` hooks, all attributes are computed lazily, so
there is no speed penalty if only those attributes which are lightweight to
compute are used.
.. attribute:: dircmp.left_list
Files and subdirectories in *a*, filtered by *hide* and *ignore*.
.. attribute:: dircmp.right_list
Files and subdirectories in *b*, filtered by *hide* and *ignore*.
.. attribute:: dircmp.common
Files and subdirectories in both *a* and *b*.
.. attribute:: dircmp.left_only
Files and subdirectories only in *a*.
.. attribute:: dircmp.right_only
Files and subdirectories only in *b*.
.. attribute:: dircmp.common_dirs
Subdirectories in both *a* and *b*.
.. attribute:: dircmp.common_files
Files in both *a* and *b*
.. attribute:: dircmp.common_funny
Names in both *a* and *b*, such that the type differs between the directories,
or names for which :func:`os.stat` reports an error.
.. attribute:: dircmp.same_files
Files which are identical in both *a* and *b*.
.. attribute:: dircmp.diff_files
Files which are in both *a* and *b*, whose contents differ.
.. attribute:: dircmp.funny_files
Files which are in both *a* and *b*, but could not be compared.
.. attribute:: dircmp.subdirs
A dictionary mapping names in :attr:`common_dirs` to :class:`dircmp` objects.