filecmp 是否进行精确比较？

Question

filecmp.cmp documentation 状态（强调我的）

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.

这里的似乎是什么意思？我的理解是 shallow=False 比较文件的内容，因此文件明确地相同或不同。

Answer 1

源代码相当简单； filecmp 模块的文档页面中有一个 link，在顶部：

def cmp(f1, f2, shallow=True):
    """Compare two files.
    Arguments:
    f1 -- First file name
    f2 -- Second file name
    shallow -- Just check stat signature (do not read the files).
               defaults to True.
    Return value:
    True if the files are the same, False otherwise.
    This function uses a cache for past comparisons and the results,
    with cache entries invalidated if their stat information
    changes.  The cache may be cleared by calling clear_cache().
    """

    s1 = _sig(os.stat(f1))
    s2 = _sig(os.stat(f2))
    if s1[0] != stat.S_IFREG or s2[0] != stat.S_IFREG:
        return False
    if shallow and s1 == s2:
        return True
    if s1[1] != s2[1]:
        return False

    outcome = _cache.get((f1, f2, s1, s2))
    if outcome is None:
        outcome = _do_cmp(f1, f2)
        if len(_cache) > 100:      # limit the maximum size of the cache
            clear_cache()
        _cache[f1, f2, s1, s2] = outcome
    return outcome

def _sig(st):
    return (stat.S_IFMT(st.st_mode),
            st.st_size,
            st.st_mtime)

def _do_cmp(f1, f2):
    bufsize = BUFSIZE
    with open(f1, 'rb') as fp1, open(f2, 'rb') as fp2:
        while True:
            b1 = fp1.read(bufsize)
            b2 = fp2.read(bufsize)
            if b1 != b2:
                return False
            if not b1:
                return True

是的，它会比较文件内容。

filecmp 是否进行精确比较？

Does filecmp do an exact comparison?

python

compare

file

python-3.x