# Rename doc\_id in logstash output

**URL:** <https://discuss.elastic.co/t/rename-doc-id-in-logstash-output/207479>\
**Category:** Logstash\
**Created:** [November 12, 2019, 9:36am UTC](https://discuss.elastic.co/t/rename-doc-id-in-logstash-output/207479 "2019-11-12T09:36:35Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Anuwa\_A](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/anuwa_a/32/47533_2.png) [@Anuwa\_A](https://discuss.elastic.co/u/Anuwa_A)\
**Post date:** [November 12, 2019, 9:36am UTC](https://discuss.elastic.co/t/rename-doc-id-in-logstash-output/207479/1 "2019-11-12T09:36:35Z")

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i want to sub-string id and ädd it in front of the id with \_ and store that as doc\_id in es out put.  
i tried below but doesn't work

id = %{id}[0..1]+"_"+%{id}  
elasticsearch {  
document\_id =\> "%{id}[0..1]+"_"+%{id}"  
}

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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:** [December 10, 2019, 9:36am UTC](https://discuss.elastic.co/t/rename-doc-id-in-logstash-output/207479/2 "2019-12-10T09:36:38Z")

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