# 11.5 `filecmp` -- File and Directory Comparisons

The `filecmp` module defines functions to compare files and directories, with various optional time/correctness trade-offs.

The `filecmp` module defines the following functions:

`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 `os.stat()` signatures are taken to be equal.

  Files that were compared using this function will not be compared again unless their `os.stat()` signature changes.

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

`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 `filecmp.cmp()`.

Example:

    >>> import filecmp
    >>> filecmp.cmp('libundoc.tex', 'libundoc.tex')
    True
    >>> filecmp.cmp('libundoc.tex', 'lib.tex')
    False