Splunk Search

RegEx for variable message field extraction

johnebgood
Path Finder

Hello, I have logs coming in that look like the following:

(Tab between columns)

server1.something.com ApacheLog 0 10.0.0.1

server2.something.com ApacheLog 0 10.0.0.2

server3.something.com GenericLog 0 0 0 0

server4.something.com GenericLog 0 0 0 0

Using the IPs to have splunk generate a pattern results in this regex:

(?i)^(?:[^\t]*\t){3}(?P<FIELDNAME>[^ ]+)

The IP will be in the same place every time ApacheLog is present... so basically I want my RegEx to be something like the following which doesn't work:

^*\t*ApacheLog*\t*\t(?P<FIELDNAME>[^ ]+)

Any assistance would be appreciated.

Thanks,
John

Tags (3)
1 Solution

Rob
Splunk Employee
Splunk Employee

Hi John,

Try the following regex:

\s+ApacheLog\s+\d\s+(?<MyFieldName>(?:\d{1,3}\.){3}\d{1,3})

You can test that by using the rex command on your events and seeing if the field contains what you expect. For example:

|rex field=_raw "\s+ApacheLog\s+\d\s+(?<MyFieldName>(?:\d{1,3}\.){3}\d{1,3})"

View solution in original post

Rob
Splunk Employee
Splunk Employee

Hi John,

Try the following regex:

\s+ApacheLog\s+\d\s+(?<MyFieldName>(?:\d{1,3}\.){3}\d{1,3})

You can test that by using the rex command on your events and seeing if the field contains what you expect. For example:

|rex field=_raw "\s+ApacheLog\s+\d\s+(?<MyFieldName>(?:\d{1,3}\.){3}\d{1,3})"

johnebgood
Path Finder

Perfect, thanks!

0 Karma

Rob
Splunk Employee
Splunk Employee

Using the interactive field extractor, the syntax its looking for will be slightly different. Try the following there:

.*\s+ApacheLog\s+\d\s+(?P<MyFieldName>(?:\d{1,3}\.){3}\d{1,3})

johnebgood
Path Finder

This works in the search field however when I attempt to edit the pattern in "Extract Fields" I get a "Invalid regex: syntax error". Any thoughts there?

Thanks!

0 Karma
Get Updates on the Splunk Community!

Why You Can't Miss .conf25: Unleashing the Power of Agentic AI with Splunk & Cisco

The Defining Technology Movement of Our Lifetime The advent of agentic AI is arguably the defining technology ...

Deep Dive into Federated Analytics: Unlocking the Full Power of Your Security Data

In today’s complex digital landscape, security teams face increasing pressure to protect sprawling data across ...

Your summer travels continue with new course releases

Summer in the Northern hemisphere is in full swing, and is often a time to travel and explore. If your summer ...