Extract error log information from logfle

exlog.py

#!/usr/bin/env python
# coding: utf-8

'''
Extract error log information from logfle

run:
$ python exlog.py file.log
Please enter an integer, last n (n > 1) day you want to extract:
Exactract finished.

and see the result: E_file.log

Log Template:
[INFO 2015-09-06 15:46:06,206 ....
[WARNING 2015-09-06 15:05:08,525 .....
[ERROR 2015-09-06 13:56:44,398 .......
Traceback (most recent call last):
  File ".....
TypeError: '......
'''

import sys
import re
from datetime import datetime, timedelta

def parse_log_file(file_name, result_file, start_date):
    enter_error_line = False
    with open(file_name, 'r') as f:
        for line in f:
            if re.match('\[ERROR', line) != None or re.match('\[WARNING', line):
                line_date_re = re.search(r'\b\d{4}[-]\d{2}[-]\d{2}\b', line)
                if line_date_re:
                    line_date = datetime.strptime(line_date_re.group(), '%Y-%m-%d')
                    line_date = line_date.date()
                    if line_date >= start_date:
                        if enter_error_line is True:
                            result_file.write('\n')
                        else:
                            enter_error_line = True
                        result_file.write(line)
                else:
                    if enter_error_line is True:
                        result_file.write('\n')
                    else:
                        enter_error_line = True
                    result_file.write(line)
                

            elif enter_error_line == True and re.match('\[INFO', line) == None:
                result_file.write(line) 

            elif re.match('\[INFO', line) != None:
                if enter_error_line == True:
                    result_file.write('\n')
                enter_error_line = False  


if __name__ == "__main__":

    file_path = sys.argv[1]

    n = int(raw_input("Please enter an integer, last n (n > 1) day you want to extract: "))
    start_date = datetime.now().date() - timedelta(days=n)

    print 'Try to exatract error logs from:'
    print file_path

    result_file = open('E_'+file_path, 'w')

    parse_log_file(file_path, result_file, start_date)
    parse_log_file(file_path+'.1', result_file, start_date)
    
    result_file.close()

    print 'Exactract finished.'