How can time be compared

[Dave Elfers]

Hello,

I am writing a script that is going to download and read XML data from a server. The server updates the xml data every 4 hours. Instead of downloading a new copy of the xml everytime the script runs, I want to look at the timestamp of the local file to see if it is less than 4 hours old. If it is, I will read the local copy, but if not I will download a new copy and read it. I can't seem to find any good way of doing this. Any help would be appreciated.

[dwblas]

Try os.stat() and use either ctime, mtime, or stime, depending on your requirements http://docs.python.org/library/os.html. Note that all times must be in the same units, seconds since the epoch, or datetime format.

[bvdet]

Here's a simple example using os.path.getmtime and time.time:

import time, os
 
def mtime_diff(fn):
    '''
    Return the difference between the current time and the time of
    last modification of a given file name in seconds.'''
    return time.time() - os.path.getmtime(fn)
 
diff = mtime_diff('file_name')
fourhours = 60*60*4.
print "The file was last modified %.2f hours ago." % (diff/fourhours)

[Dave Elfers]

thank you sir. That did the trick!