11.5. filecmp — File and Directory Comparisons
Source code: Lib/filecmp.py
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.
11.5.1. The dircmp class
-
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
-
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')
>>> print_diff_files(dcmp)