从文件中读取行并选择python

Question

the problem is, there is a log file that contains: path /var/log/iptraf/logi

Fri Mar 23 12:42:19 2012; TCP; eth0; 52 bytes; 
Fri Mar 23 12:43:21 2012; TCP; eth0; 52 bytes; 
Fri Mar 23 12:44:28 2012; TCP; eth0; 52 bytes; 
Fri Mar 23 12:45:29 2012; TCP; eth0; 52 bytes;
Fri Mar 23 12:46:30 2012; TCP; eth0; 52 bytes; 
Fri Mar 23 12:47:31 2012; TCP; eth0; 52 bytes;

I need to know the traffic spent the last two minutes of the date of this Code

#!/usr/bin/env python
#-*- coding: utf-8 -*-
import re, sys, datetime

cutoff = datetime.datetime.now() - datetime.timedelta(minutes=2)
timestr = str(cutoff)[11:19]

# Open files:
data = open('/var/log/iptraf/logi', 'r')
output = open('/var/log/iptraf/logs', 'w')
dd=data.find('timestr')
output.write("%s" %dd)

But i got mistake

dd=data.find('timestr')
AttributeError: 'file' object has no attribute 'find'

how do I optimize the code so that he was looking for a string in the last two minutes and wrote down traffic like this in other file /var/log/iptraf/logs

Fri Mar 23 12:46:30 2012; TCP; eth0; 52 bytes; 
Fri Mar 23 12:47:31 2012; TCP; eth0; 52 bytes;

Answer 1

Indeed, the open() function does not return a String. Rather, it returns a File . Files are iterable, so it would be possible to consider every line like this:

for line in data:
    if timestr in line:
        output.write(line)

Thing is, your most recent times will be at the end of your log file, so to save time you'd rather read backwards. I recommend taking a look at this page from the Python Cookbook for a nice way to do that.

Answer 2

open doesn't return a string. Use data.read().find('timestr') if you're OK with reading the whole file at once. If not, I'd suggest a loop, see http://www.yak.net/fqa/171.html