# Referencing an Environment Variable when existing field content is part of the name
**URL:** https://discuss.elastic.co/t/referencing-an-environment-variable-when-existing-field-content-is-part-of-the-name/158709
**Category:** Logstash
**Created:** [November 29, 2018, 8:22am UTC](https://discuss.elastic.co/t/referencing-an-environment-variable-when-existing-field-content-is-part-of-the-name/158709 "2018-11-29T08:22:59Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@Krobar](https://discuss.elastic.co/u/Krobar)
#### Post date: [November 29, 2018, 8:22am UTC](https://discuss.elastic.co/t/referencing-an-environment-variable-when-existing-field-content-is-part-of-the-name/158709/1 "2018-11-29T08:22:59Z")
Is this possible?
I have tried various configs including the one below:
mutate {
add\_field =\> {
"BRAND\_VERSION\_NAME" =\> "BRAND\_VERSION\_%{Region}\_%{Language}"
"BRAND\_VERSION" =\> "'${%{BRAND\_VERSION\_NAME}}'"
}
}
BRAND\_VERSION\_NAME does contain the correct environment variable name but the variable name just gets printed for BRAND\_VERSION (Rather than the contents of the environment variable)
---
### Author:  [@Eniqmatic](https://discuss.elastic.co/u/Eniqmatic)
#### Post date: [November 29, 2018, 8:25am UTC](https://discuss.elastic.co/t/referencing-an-environment-variable-when-existing-field-content-is-part-of-the-name/158709/2 "2018-11-29T08:25:37Z")
That's because I think you are adding them within the same add\_field function, so technically the field does not exist yet when processing. Try splitting it out into a different mutate filter to test first. Also do you need the "$" in the brand\_version field name?
---
### Author:  [@Krobar](https://discuss.elastic.co/u/Krobar)
#### Post date: [November 29, 2018, 11:30am UTC](https://discuss.elastic.co/t/referencing-an-environment-variable-when-existing-field-content-is-part-of-the-name/158709/3 "2018-11-29T11:30:14Z")
Thank you for the reply. I tried separating out the adds as hown below but the result is still the same:
add\_field =\> {
"BRAND\_VERSION\_NAME" =\> "BRAND\_VERSION\_%{Region}\_%{Language}"
}
add\_field =\> {
"BRAND\_VERSION" =\> "'${%{BRAND\_VERSION\_NAME}}'"
}
Any more ideas on how to fix this?
---
### Author:  [@Eniqmatic](https://discuss.elastic.co/u/Eniqmatic)
#### Post date: [November 29, 2018, 12:12pm UTC](https://discuss.elastic.co/t/referencing-an-environment-variable-when-existing-field-content-is-part-of-the-name/158709/4 "2018-11-29T12:12:37Z")
Try them in different mutate filters as above! Also I ask again, did you mean to put the dollar symbol in the field?
```
mutate {
add_field => {
"BRAND_VERSION_NAME" => "BRAND_VERSION_%{Region}_%{Language}"
}
}
mutate {
add_field => {
"BRAND_VERSION" => "'${%{BRAND_VERSION_NAME}}'"
}
}
```
---
### Author:  [@Krobar](https://discuss.elastic.co/u/Krobar)
#### Post date: [November 29, 2018, 12:48pm UTC](https://discuss.elastic.co/t/referencing-an-environment-variable-when-existing-field-content-is-part-of-the-name/158709/5 "2018-11-29T12:48:58Z")
Thanks again but no luck. I think I do want the dollar symbol because I think this needs to be there to refer to the Environment variable.
So for example the fields could be:
Region="cn"
Lanuage="en"
I would be looking to get the content of an environment variable called BRAND\_VERSION\_cn\_en.
---
### Author:  [@Eniqmatic](https://discuss.elastic.co/u/Eniqmatic)
#### Post date: [November 29, 2018, 1:29pm UTC](https://discuss.elastic.co/t/referencing-an-environment-variable-when-existing-field-content-is-part-of-the-name/158709/6 "2018-11-29T13:29:21Z")
No to refer to the field it is just %{BRAND\_VERSION\_NAME}
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [December 27, 2018, 1:29pm UTC](https://discuss.elastic.co/t/referencing-an-environment-variable-when-existing-field-content-is-part-of-the-name/158709/7 "2018-12-27T13:29:22Z")
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