python不打开文件情况下如何获得大文件md5值的方法，pythonmd5,用hashlib.md5

def md5_for_file(f, block_size=2**20):    md5 = hashlib.md5()    while True:        data = f.read(block_size)        if not data:            break        md5.update(data)    return md5.digest()

def md5(f):

cmd = "md5sum " + fimport subprocessfp = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)(s,e) = fp.communicate()result = (s.decode()).strip()e = (e.decode()).strip()return (result, e)