# What is Logstash regex engine?

**URL:** <https://discuss.elastic.co/t/what-is-logstash-regex-engine/271387>\
**Category:** Logstash\
**Created:** [April 27, 2021, 1:48pm UTC](https://discuss.elastic.co/t/what-is-logstash-regex-engine/271387 "2021-04-27T13:48:04Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![grumo35](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/grumo35/32/59451_2.png) [@grumo35](https://discuss.elastic.co/u/grumo35)\
**Post date:** [April 27, 2021, 1:48pm UTC](https://discuss.elastic.co/t/what-is-logstash-regex-engine/271387/1 "2021-04-27T13:48:04Z")

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Hi,

Just came across some regex in config files today and i cannot figure out which engine it is based on and documentation about the syntax i should use in my config.

the thing i've stumbled across :

```auto
if [field] !~ /.+\.dll/

```

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<div class="post-metadata">

**Author:** ![Badger](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/badger/32/25190_2.png) [@Badger](https://discuss.elastic.co/u/Badger)\
**Post date:** [April 27, 2021, 2:06pm UTC](https://discuss.elastic.co/t/what-is-logstash-regex-engine/271387/2 "2021-04-27T14:06:09Z")

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grok is built upon [Oniguruma](https://www.elastic.co/guide/en/logstash/current/plugins-filters-grok.html#_regular_expressions), but I think the rest of logstash uses standard [Ruby](https://ruby-doc.org/core-3.0.1/Regexp.html) expressions.

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<div class="post-metadata">

**Author:** ![grumo35](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/grumo35/32/59451_2.png) [@grumo35](https://discuss.elastic.co/u/grumo35)\
**Post date:** [April 27, 2021, 3:10pm UTC](https://discuss.elastic.co/t/what-is-logstash-regex-engine/271387/3 "2021-04-27T15:10:08Z")

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Thanks for you fast reply as usual 😉

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [May 25, 2021, 3:10pm UTC](https://discuss.elastic.co/t/what-is-logstash-regex-engine/271387/4 "2021-05-25T15:10:27Z")

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