topic Re: PCRE Regex not working in Splunk in Splunk Search

PCRE Regex not working in Splunk

eprince — Fri, 20 Dec 2019 11:04:47 GMT

Required API call, RegEx i tried in https://regex101.com/ and the Regex which works in Splunk are given below.

/Contact/v1/15965755/Order
\/Contact\/v1\/[0-9]{1,}/Order
/Contact/v1/*/Order

Why PCRE regex not working in Splunk? If i add $ at the end to limit the search, that also not working.
Somebody please throw some light on this.

Thanks...

Re: PCRE Regex not working in Splunk

bshuler_splunk — Fri, 20 Dec 2019 15:39:29 GMT

What isn't working for you?

| makeresults 
|  eval data = "/Contact/v1/15965755/Order"
| rex field=data "^\/Contact\/v1\/(?<field>[0-9]{1,})/Order$"

Re: PCRE Regex not working in Splunk

eprince — Fri, 20 Dec 2019 16:12:22 GMT

\/Contact\/v1\/[0-9]{1,}/Order is not working in Splunk to return /Contact/v1/15965755/Order.
But its working in RegEx101 online validation.

Re: PCRE Regex not working in Splunk

to4kawa — Sat, 21 Dec 2019 01:05:05 GMT

| makeresults 
| eval _raw="/Contact/v1/15965755/Order"
| rex "(?<=\/)(?<value>\d+)"

Hi, @eprince
Some strange signs may be in it, so what about this?

Re: PCRE Regex not working in Splunk

mydog8it — Sun, 22 Dec 2019 23:45:54 GMT

Line #2 is missing an escape on the backslash preceding "/Order".

Try this:
\/Contact\/v1\/[0-9]{1,}\/Order

Re: PCRE Regex not working in Splunk

to4kawa — Sun, 22 Dec 2019 23:55:00 GMT

That's right.

Re: PCRE Regex not working in Splunk

vnravikumar — Mon, 23 Dec 2019 06:26:58 GMT

Check this

| makeresults 
| eval temp="/Contact/v1/15965755/Order" 
| rex field=temp "(?P<result>\d+[^\/])"

Re: PCRE Regex not working in Splunk

jpolvino — Thu, 26 Dec 2019 16:51:09 GMT

I like to keep things simple with lookaround constructs. Very powerful, easy to maintain, and worth exploring for cases like this.

| rex "(?<orderNum>\d+)(?=\/Order)"

Translation: Grab the numbers that precede /Order. See https://regex101.com/r/Qq2qaV/1

Re: PCRE Regex not working in Splunk

woodcock — Thu, 26 Dec 2019 20:00:06 GMT

Be aware that RegEx101.com does not start our in PCRE mode, you have to SET IT THAT WAY by selecting the PCRE (PHP) option under the Flavors menu in the left pane! Also note on the very right edge of the RegEx text input it shows some REGEX FLAGS of which g and m are set by default but only the g is always correct for Splunk. For example, rex and regex commands DO NOT use m by default (but LINE_BREAKER does), so you must prefix your RegEx with (?m) to make it work the same way in Splunk (or de-select the m flag on RegEx101.com).

Also be aware that splunk has both pcregextest and regextest CLI tools that you can use:
https://docs.splunk.com/Documentation/Splunk/latest/Admin/CLIadmincommands