Python RegEx - Getting multiple pieces of information out of a string

Question

I'm trying to use python to parse a log file and match 4 pieces of information in one regex. (epoch time, SERVICE NOTIFICATION, hostname and CRITICAL) I can't seem to get this to work. So Far I've been able to only match two of the four. Is it possible to do this? Below is an example of a string from the log file and the code I've gotten to work thus far. Any help would make me a happy noob.

[1242248375] SERVICE ALERT: myhostname.com;DNS: Recursive;CRITICAL;SOFT;1;CRITICAL - Plugin timed out while executing system call

hostname = options.hostname

n = open('/var/tmp/nagios.log', 'r')
n.readline()
l = [str(x) for x in n]
for line in l:
    match = re.match (r'^\[(\d+)\] SERVICE NOTIFICATION: ', line)
    if match:
       timestamp = int(match.groups()[0])
       print timestamp

Alex Martelli · Accepted Answer · 2009-05-29 02:25:19Z

6

You can use | to match any one of various possible things, and re.findall to get all non-overlapping matches to some RE.

answered May 29, 2009 at 2:25

Alex Martelli

887k175 gold badges1.3k silver badges1.4k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Dietrich Epp · Accepted Answer · 2009-05-29 02:33:57Z

2

The question is a bit confusing. But you don't need to do everything with regular expressions, there are some good plain old string functions you might want to try, like 'split'.

This version will also refrain from loading the entire file in memory at once, and it will close the file even when an exception is thrown.

regexp = re.compile(r'\[(\d+)\] SERVICE NOTIFICATION: (.+)')
with open('var/tmp/nagios.log', 'r') as file:
    for line in file:
        fields = line.split(';')
        match = regexp.match(fields[0])
        if match:
            timestamp = int(match.group(1))
            hostname = match.group(2)

answered May 29, 2009 at 2:33

Dietrich Epp

216k39 gold badges366 silver badges426 bronze badges

Comments

Mike Kale · Accepted Answer · 2009-05-29 02:55:00Z

2

You can use more than one group at a time, e.g.:

import re

logstring = '[1242248375] SERVICE ALERT: myhostname.com;DNS: Recursive;CRITICAL;SOFT;1;CRITICAL - Plugin timed out while executing system call'
exp = re.compile('^\[(\d+)\] ([A-Z ]+): ([A-Za-z0-9.\-]+);[^;]+;([A-Z]+);')
m = exp.search(logstring)

for s in m.groups():
    print s

answered May 29, 2009 at 2:55

Mike Kale

4,1333 gold badges29 silver badges30 bronze badges

2 Comments

Jon-Eric Over a year ago

Just FYI, exp.match(logstring) works just as well in this example. I.e., the solution ISN'T use search() instead of match().

Mike Kale Over a year ago

Sure, good point. I'm in the habit of using search instead of match, but since we're starting at the beginning of the string it's the same thing. The key is adding four different grouping parens to grab the four things the OP wants.

user114075 · Accepted Answer · 2009-05-29 02:38:31Z

1

If you are looking to split out those particular parts of the line then.

Something along the lines of:

match = re.match(r'^\[(\d+)\] (.*?): (.*?);.*?;(.*?);',line)

Should give each of those parts in their respective index in groups.

answered May 29, 2009 at 2:38

user114075

111 bronze badge

Comments

Oddthinking · Accepted Answer · 2009-05-29 02:29:27Z

0

Could it be as simple as "SERVICE NOTIFICATION" in your pattern doesn't match "SERVICE ALERT" in your example?

answered May 29, 2009 at 2:29

Oddthinking

25.5k21 gold badges86 silver badges126 bronze badges

Collectives™ on Stack Overflow

Python RegEx - Getting multiple pieces of information out of a string

5 Answers 5

Comments

Comments

2 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

Comments

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related