[syslog-ng] Python help

[chris packham]

On Wed, 2009-09-16 at 11:03 +0530, Jain, Vaibhav (GE Healthcare) wrote:
> Hi,
>  
> I am using a python parser for parsing the incoming message from
> syslog-ng. In my log messages some fields are optional and some are
> not.I want to know how to handle these optional parameters in the
> python regual expression.
>  

Your question is about python not syslog so you might have more luck
from a python forum/mailing list. 

Having said that, the standard way of making a group optional in a regex
is to add ? after it e.g. \d(\w+)? means a single digit followed by and
optional string of word characters.

Here's a small snippet I whipped up based on your example data.

---

import re;

data = ['Sep 15 22:23:37 ecis007 codeSystemName=5 UserID="Admin"',
    'Sep 15 22:23:37 ecis007 UserID="Admin"']

r = re.compile (r'(\w+)\s+(\d+)\s+(\d\d:\d\d:\d\d)\s+([^\s]+)\s+(codeSystemName=(\d+)\s+)?(.*)')

for d in data:
    print "d="+d
    m = r.match(d);
    if m:
        print repr(m.groups())

---

# python test.py 
d=Sep 15 22:23:37 ecis007 codeSystemName=5 UserID="Admin"
('Sep', '15', '22:23:37', 'ecis007', 'codeSystemName=5 ', '5',
'UserID="Admin"')
d=Sep 15 22:23:37 ecis007 UserID="Admin"
('Sep', '15', '22:23:37', 'ecis007', None, None, 'UserID="Admin"')