parse date/time from a log entry with only strftime (and no regexen)

[Simon Mullis]

Hi All

I'm writing a script to help with analyzing log files timestamps and have a
very specific question on which I'm momentarily stumped....

I'd like the script to support multiple log file types, so allow a strftime
format to be passed in as a cli switch (default is %Y-%m-%d %H:%M:%S).

When it comes to actually doing the analysis I want to store or discard the
log entry based on certain criteria. In fact, I only need the log line
timestamp.

I'd like to do this in one step and therefore not require the user to supply
a regex aswell as a strftime format:

>>> import datetime
>>> p = datetime.datetime.strptime("2008-07-23 12:18:28 this is the
remainder of the log line that I do not care about", "%Y-%m-%d %H:%M:%S")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/local/lib/python2.5/_strptime.py", line 333, in strptime
    data_string[found.end():])
ValueError: unconverted data remains:  this is the remainder of the log line
that I do not care about

>>> repr(p)
NameError: name 'p' is not defined

Clearly the strptime method above can grab the right bits of data but the
string "p" is not created due to the error.

So, my options are:

1 - Only support one log format.

2 - Support any log format but require a regex as well as a strftime format
so I can extract the "timestamp" portion.

3 - Create another class/method with a lookup table for the strftime options
that automagically creates the correct regex to extract the right string
from the log entry... (or is this overly complicated)

4 - Override the method above (strptime) to allow what I'm trying to do).

4 - Some other very clever and elegant solution that I would not ever manage
to think of myself....


Am I making any sense whatsoever?

Thanks

SM

(P.S The reason I don't want the end user to supply a regex for the
timestamin he log-entry is that we're already using 2 other regexes as cli
switches to select the file glob and log line to match....)
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