# Mutate fields

**URL:** <https://discuss.elastic.co/t/mutate-fields/175489>\
**Category:** Logstash\
**Created:** [April 4, 2019, 10:20pm UTC](https://discuss.elastic.co/t/mutate-fields/175489 "2019-04-04T22:20:10Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![therealtoby](https://avatars.discourse-cdn.com/v4/letter/t/ea666f/32.png) [@therealtoby](https://discuss.elastic.co/u/therealtoby)\
**Post date:** [April 4, 2019, 10:20pm UTC](https://discuss.elastic.co/t/mutate-fields/175489/1 "2019-04-04T22:20:10Z")

</div>

Hello,

I need to change the below. I'm using mutate and rename within.

When I do

```
mutate {
update => {
"source-address" => "source.ip"
        }
}

```

I get the result

"source.ip" =\> "0.0.0.0" --\> this works the way it is expected.

What I want is source-address becoming [source][ip] in the square brackets. I tried rename, update, etc. but I'm not able to figure it out. What's the best possible way to achieve this?

"source-address" =\> "[source][ip]"

Thank you

---

<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 5, 2019, 12:47pm UTC](https://discuss.elastic.co/t/mutate-fields/175489/2 "2019-04-05T12:47:29Z")

</div>

```
mutate { rename => { "source-address" => "[source][ip]" } }
```

---

<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 3, 2019, 12:47pm UTC](https://discuss.elastic.co/t/mutate-fields/175489/3 "2019-05-03T12:47:45Z")

</div>

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