# Logstash if and Mutate hostname

**URL:** <https://discuss.elastic.co/t/logstash-if-and-mutate-hostname/90449>\
**Category:** Logstash\
**Created:** [June 22, 2017, 12:07pm UTC](https://discuss.elastic.co/t/logstash-if-and-mutate-hostname/90449 "2017-06-22T12:07:37Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Sinethra\_Seneviratne](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/sinethra_seneviratne/32/19417_2.png) [@Sinethra\_Seneviratne](https://discuss.elastic.co/u/Sinethra_Seneviratne)\
**Post date:** [June 22, 2017, 12:07pm UTC](https://discuss.elastic.co/t/logstash-if-and-mutate-hostname/90449/1 "2017-06-22T12:07:37Z")

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hi, im trying to filter my S3 logs and change Original value of the " cs\_host " field to a different one, This is the filter block of my Logstash conf. But this isn't working. Please let me know whats wrong here.

> filter {  
> grok {  
> match =\> { "message" =\> "%{S3\_ACCESS\_LOG}"}  
> }  
> date {  
> locale =\> "en"  
> match =\> ["timestamp", "d/MMM/YYYY:HH:mm:ss Z"]  
> }  
> if [cs\_host] == "[host1.example.com](http://host1.example.com)" {  
> mutate {  
> replace =\> ["cs\_host", "host1"]  
> }  
> }  
> if [cs\_host] == "[host2.example.com](http://host2.example.com)" {  
> mutate {  
> replace =\> ["cs\_host", "host2"]  
> }  
> }  
> }

---

<div class="post-metadata">

**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 22, 2017, 12:40pm UTC](https://discuss.elastic.co/t/logstash-if-and-mutate-hostname/90449/2 "2017-06-22T12:40:55Z")

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Please show an example event produced by Logstash. Use a `stdout { codec => rubydebug }` output.

---

<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:** [July 20, 2017, 12:40pm UTC](https://discuss.elastic.co/t/logstash-if-and-mutate-hostname/90449/3 "2017-07-20T12:40:58Z")

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