# FAQ about the \*\*pattern\_definitions\*\* option in grok

**URL:** <https://discuss.elastic.co/t/faq-about-the-pattern-definitions-option-in-grok/87871>\
**Category:** Logstash\
**Created:** [June 1, 2017, 9:23am UTC](https://discuss.elastic.co/t/faq-about-the-pattern-definitions-option-in-grok/87871 "2017-06-01T09:23:38Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Fly](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/fly/32/17992_2.png) [@Fly](https://discuss.elastic.co/u/Fly)\
**Post date:** [June 1, 2017, 9:23am UTC](https://discuss.elastic.co/t/faq-about-the-pattern-definitions-option-in-grok/87871/1 "2017-06-01T09:23:38Z")

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Hi all  
Can give me more description of **pattern\_definitions** option.  
When I read it in the configuration of the pipeline logstash with filebeat module.  
I do not yet understand its functionality in the configuration ☹

> pattern\_definitions =\> {  
> "GREEDYMULTILINE"=\> "(.|\n)\*"  
> }  
> ☹ ☹ ☹

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**Author:** ![magnusbaeck](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/magnusbaeck/32/44943_2.png) [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)\
**Post date:** [June 1, 2017, 8:24pm UTC](https://discuss.elastic.co/t/faq-about-the-pattern-definitions-option-in-grok/87871/2 "2017-06-01T20:24:24Z")

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I'm not sure what is unclear. It allows you to define extra grok patterns that you can use in your grok expressions. Like a grok pattern file but inside your Logstash configuration file.

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [June 29, 2017, 8:24pm UTC](https://discuss.elastic.co/t/faq-about-the-pattern-definitions-option-in-grok/87871/3 "2017-06-29T20:24:29Z")

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