Python读取文件后n行的代码示例

# -*- coding:utf8-*-
import os
import time
import datetime
import math
import string
def get_last_line(inputfile) :
 filesize = os.path.getsize(inputfile)
 blocksize = 1024
 dat_file = open(inputfile, &＃39;r&＃39;)
 last_line = ""
 lines = dat_file.readlines()
 count = len(lines)
 if count>60:
   num=60
 else:
   num=count
 i=1;
 lastre = []
 for i in range(1,(num+1)):
   if lines :
     n = -i
     last_line = lines[n].strip()
     #print "last line : ", last_line
     dat_file.close()
     #print i
     lastre.append(last_line)
 return lastre
#获取最后一行的结果
re = get_last_line(&＃39;../update/log/rtime/rtime20130805.log&＃39;)
print len(re)
for n in re:
  strlist = n.split(&＃39;  &＃39;)
  if strlist[1] == &＃39;ok&＃39; and string.atoi(strlist[2])>1000:
     print &＃39;数据条数正常&＃39;
     print &＃39;OK&＃39;
  else:
     print &＃39;数据太少，检查发邮件&＃39;

以上处理和日志文件格式为

2013-08-05 16:09:30  ok  1673
2013-08-05 16:10:34  ok  1628
2013-08-05 16:11:55  ok  71
2013-08-05 16:13:02  ok  1441
2013-08-05 16:14:06  ok  1634
2013-08-05 16:15:10  ok  1717
2013-08-05 16:16:14  ok  1687
2013-08-05 16:17:18  ok  1642
2013-08-05 16:18:27  ok  1655
2013-08-05 16:19:33  ok  1655

读取最后一行：

#返回文件最后一行函数
def get_last_line(inputfile) :
 filesize = os.path.getsize(inputfile)
 blocksize = 1024
 dat_file = open(inputfile, &＃39;r&＃39;)
 last_line = ""
 if filesize > blocksize :
   maxseekpoint = (filesize // blocksize)
   dat_file.seek((maxseekpoint-1)*blocksize)
 elif filesize :
   #maxseekpoint = blocksize % filesize
   dat_file.seek(0, 0)
 lines = dat_file.readlines()
 if lines :
   last_line = lines[-1].strip()
 #print "last line : ", last_line
 dat_file.close()
 return last_line