使用open打开文本都后一行

读取日志最后一行的实现方法：

1.txt内容

2017-1-23 falkdfj0coveenfhi;'aodjf
2017-1-24 adsfl;jka;dfixnjkla;f;jkncvhjfnbhdjknb
2017-1-25 aldkfjlakdfjosjjiangjiangkdjf;kj;flkjdlkjlkajf
2017-1-25 aldkfjlakdfjosjjiangjiangkdjf;kj;flkjdlkjlkajf
2017-1-25 aldkfjlakdfjosjjiangjiangkdjf;kj;flkjdlkjlkajf
2017-1-25 aldkfjlakdfjosjjiangjiangkdjf;kj;flkjdlkjlkajf
2017-1-25 aldkfjlakdfjosjjiangjiangkdjf;kj;flkjdlkjlkajf65
2017-1-25 aldkfjlakdfjosjjiangjiangkdjf;kj;flkjdlkjlkajf65
2017-1-25 aldkfjlakdfjosjjiangjiangkdjf;kj;flkjdlkjlkajf56
2017-1-25 aldkfjlakdfjosjjiangjiangkdjf;kj;flkjdlkjlkajf324
2017-1-25 aldkfjlakdfjosjjiangjiangkdjf;kj;flkjdlkjlkajf435
2017-1-25 aldkfjlakdfjosjjiangjiangkdjf;kj;flkjdlkjlkajf234
2017-1-25 aldkfjlakdfjosjjiangjiangkdjf;kj;flkjdlkjlkajf34
2017-1-25 aldkfjlakdfjosjjiangjiangkdjf;kj;flkjdlkjlkajf454
2017-1-25 023i;kjglkcojngkdjf;kj;flkjdlkjlkajf343
2017-1-25 aldkfjlakdfjosjsdfwsdjf;kj;flkjdlkjlkajf21312
2017-1-25 aladf;alksjd02fx90g;kj;flkjdlkjlkajf123123
2017/1/26 aing;lkfj; ojiangjiang';lkj;l,mn

代码如下：

f = open('1.txt','rb')
for i in f:
    offer = -10
    while 1:

        f.seek(offer,2)
        data = f.readlines()
        if len(data) > 1:
            print("last lines is :%s"%data[-1].decode("utf8"))
            break
        offer*=2