Reading log file last 5 minutes python 2.6

Question

i making a script in python for reading the last 5 minutes of a log file, this is my code so far

from datetime import datetime, timedelta

now = datetime.now()
before = timedelta(minutes=5)
now = now.replace(microsecond=0)
before = (now-before)
now = (now.strftime("%b %d %X"))
before = (before.strftime("%b %d %X"))
print(before)
print(now)

with open('user.log','r') as f:
    for line in f:
        if before in line:
            break

    for line in f:
        if now in line:
            break
        print (line.strip())

the output is Sep 03 11:47:25 Sep 03 11:52:25 which is the print to check if the time is correct, nearly 100 lines in the log that has it but dont bring me nothing, if i take the ifs out then print all the lines which proves the problem is on the if...

any ideas?

here is a exemple of my log file content:

Sep 03 10:18:47 bni..........teagagfaesa.....
Sep 03 10:18:48 bni..........teagagfaesa.....2

Answer 1

I managed to find a Python even older than yours.

#!/usr/bin/env python

from __future__ import with_statement
from datetime import datetime, timedelta

before = timedelta(minutes=5)
now = datetime.now().replace(microsecond=0, year=1900)
before = (now-before)

with open('user.log','r') as f:
    for line in f:
        if datetime.strptime(line[0:15], '%b %d %X') < before:
            continue
        print line.strip()

The change compared to your code is that we convert each time stamp from the file into a datetime object; then we can trivially compare these properly machine-readable representations the way you'd expect (whereas without parsing the dates, it can't work, except by chance -- "Sep" comes after "Aug" but "Sep" comes after "Oct", too; so it seems to work if you run it in a suitable month, but then breaks the next month!)

The year=1900 hack is because strptime() defaults to year 1900 for inputs which don't have a year.