# Please update your Logstash mutate split documentation example

**URL:** https://discuss.elastic.co/t/please-update-your-logstash-mutate-split-documentation-example/196893
**Category:** Logstash
**Created:** [August 27, 2019, 7:27am UTC](https://discuss.elastic.co/t/please-update-your-logstash-mutate-split-documentation-example/196893 "2019-08-27T07:27:37Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![MrFrost](https://avatars.discourse-cdn.com/v4/letter/m/ecc23a/32.png) [@MrFrost](https://discuss.elastic.co/u/MrFrost)
#### Post date: [August 27, 2019, 7:27am UTC](https://discuss.elastic.co/t/please-update-your-logstash-mutate-split-documentation-example/196893/1 "2019-08-27T07:27:37Z")

</div>

I was browsing mutate -\> split documentation and example is messed up, took me a while to find the solution what was wrong.

Deprecated doc link:  
[https://www.elastic.co/guide/en/logstash/current/plugins-filters-mutate.html#plugins-filters-mutate-split](https://www.elastic.co/guide/en/logstash/current/plugins-filters-mutate.html#plugins-filters-mutate-split)

Example:

```
filter {
    mutate {
        split => ["hostname", "."]
        add_field => { "shortHostname" => "%{hostname[0]}" }
    }
...
}

```

This does not work and throws: Invalid FieldReference: `hostname[0]`" in Logstash 7.3.0

The snippet that worked for me is:

```
filter {
    mutate {
        split => ["hostname", "."]
        add_field => { "shortHostname" => "%{[hostname][0]}" }
    }
...
}
```

---

<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: [September 24, 2019, 7:27am UTC](https://discuss.elastic.co/t/please-update-your-logstash-mutate-split-documentation-example/196893/2 "2019-09-24T07:27:38Z")

</div>

This topic was automatically closed 28 days after the last reply. New replies are no longer allowed.