python 读取大文件，按照字节读取

def read_bigFile():

    f = open("123.dat",'r')

    cont = f.read()

    while len(cont) > :

        print(cont)

        cont = f.read()

　　f.close()

read_bigFile()

def copyFile():

    f1 = "123.dat"

    f2 = "123.dat.bak"

    #大文件复制

    fs1 = open(f1,'r')

    fs2 = open(f2,'w')

    cont1 = fs1.readline()

    while len(cont1)>:

        #写入

        fs2.write(cont1)

        cont1 = fs1.readline()

    fs1.close()

    fs2.close()

copyFile()