Python 3.6.5 Documentation >  "filecmp" — File and Directory Comparisons

"filecmp" — File and Directory Comparisons
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**Source code:** Lib/filecmp.py

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The "filecmp" module defines functions to compare files and
directories, with various optional time/correctness trade-offs. For
comparing files, see also the "difflib" module.

The "filecmp" module defines the following functions:

filecmp.cmp(f1, f2, shallow=True)

Compare the files named *f1* and *f2*, returning "True" if they
seem equal, "False" otherwise.

If *shallow* is true, files with identical "os.stat()" signatures
are taken to be equal. Otherwise, the contents of the files are
compared.

Note that no external programs are called from this function,
giving it portability and efficiency.

This function uses a cache for past comparisons and the results,
with cache entries invalidated if the "os.stat()" information for
the file changes. The entire cache may be cleared using
"clear_cache()".

filecmp.cmpfiles(dir1, dir2, common, shallow=True)

Compare the files in the two directories *dir1* and *dir2* whose
names are given by *common*.

Returns three lists of file names: *match*, *mismatch*, *errors*.
*match* contains the list of files that match, *mismatch* contains
the names of those that don’t, and *errors* lists the names of
files which could not be compared. Files are listed in *errors* if
they don’t exist in one of the directories, the user lacks
permission to read them or if the comparison could not be done for
some other reason.

The *shallow* parameter has the same meaning and default value as
for "filecmp.cmp()".

For example, "cmpfiles('a', 'b', ['c', 'd/e'])" will compare "a/c"
with "b/c" and "a/d/e" with "b/d/e". "'c'" and "'d/e'" will each
be in one of the three returned lists.

filecmp.clear_cache()

Clear the filecmp cache. This may be useful if a file is compared
so quickly after it is modified that it is within the mtime
resolution of the underlying filesystem.

New in version 3.4.

The "dircmp" class
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class filecmp.dircmp(a, b, ignore=None, hide=None)

Construct a new directory comparison object, to compare the
directories *a* and *b*. *ignore* is a list of names to ignore,
and defaults to "filecmp.DEFAULT_IGNORES". *hide* is a list of
names to hide, and defaults to "[os.curdir, os.pardir]".

The "dircmp" class compares files by doing *shallow* comparisons as
described for "filecmp.cmp()".

The "dircmp" class provides the following methods:

report()

Print (to "sys.stdout") a comparison between *a* and *b*.

report_partial_closure()

Print a comparison between *a* and *b* and common immediate
subdirectories.

report_full_closure()

Print a comparison between *a* and *b* and common subdirectories
(recursively).

The "dircmp" class 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 "__getattr__()" hooks, all attributes are computed
lazily, so there is no speed penalty if only those attributes which
are lightweight to compute are used.

left

The directory *a*.

right

The directory *b*.

left_list

Files and subdirectories in *a*, filtered by *hide* and
*ignore*.

right_list

Files and subdirectories in *b*, filtered by *hide* and
*ignore*.

common

Files and subdirectories in both *a* and *b*.

left_only

Files and subdirectories only in *a*.

right_only

Files and subdirectories only in *b*.

common_dirs

Subdirectories in both *a* and *b*.

common_files

Files in both *a* and *b*.

common_funny

Names in both *a* and *b*, such that the type differs between
the directories, or names for which "os.stat()" reports an
error.

same_files

Files which are identical in both *a* and *b*, using the class’s
file comparison operator.

diff_files

Files which are in both *a* and *b*, whose contents differ
according to the class’s file comparison operator.

funny_files

Files which are in both *a* and *b*, but could not be compared.

subdirs

A dictionary mapping names in "common_dirs" to "dircmp" objects.

filecmp.DEFAULT_IGNORES

New in version 3.4.

List of directories ignored by "dircmp" by default.

Here is a simplified example of using the "subdirs" attribute to
search recursively through two directories to show common different
files:

>>> from filecmp import dircmp
>>> def print_diff_files(dcmp):
... for name in dcmp.diff_files:
... print("diff_file %s found in %s and %s" % (name, dcmp.left,
... dcmp.right))
... for sub_dcmp in dcmp.subdirs.values():
... print_diff_files(sub_dcmp)
...
>>> dcmp = dircmp('dir1', 'dir2') # doctest: +SKIP
>>> print_diff_files(dcmp) # doctest: +SKIP