# How do I use variables in .yml files?

**URL:** <https://discuss.elastic.co/t/how-do-i-use-variables-in-yml-files/73237>\
**Category:** Elasticsearch\
**Created:** [January 30, 2017, 4:02pm UTC](https://discuss.elastic.co/t/how-do-i-use-variables-in-yml-files/73237 "2017-01-30T16:02:31Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Airn5475](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/airn5475/32/13757_2.png) [@Airn5475](https://discuss.elastic.co/u/Airn5475)\
**Post date:** [January 30, 2017, 4:02pm UTC](https://discuss.elastic.co/t/how-do-i-use-variables-in-yml-files/73237/1 "2017-01-30T16:02:31Z")

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How do you declare and use variables inside elasticsearch.yml?? I'm running on Windows Server.

I've read this article about Environment variables, but find it to be a bit lacking.  
[https://www.elastic.co/guide/en/elasticsearch/reference/current/settings.html#\_environment\_variable\_subsitution](https://www.elastic.co/guide/en/elasticsearch/reference/current/settings.html#_environment_variable_subsitution)

Do they get passed in via the command line?  
Can they be declared and initialized at the top of the file?  
Are they the Environment Variables set under System Properties \> Advanced \> Environment Variables?

This is probably a very basic question, but I'm not familiar with .yml files and how they work.

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**Author:** ![spinscale](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/spinscale/32/25011_2.png) [@spinscale](https://discuss.elastic.co/u/spinscale)\
**Post date:** [January 31, 2017, 9:31am UTC](https://discuss.elastic.co/t/how-do-i-use-variables-in-yml-files/73237/2 "2017-01-31T09:31:34Z")

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Hey,

those are environment variables - and probably they need to set under windows as you mentioned (sorry, no windows expertise on my side), under a Linux shell you would use the `export` keyword to do that.

Hope this helps.

--Alex

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [February 28, 2017, 9:31am UTC](https://discuss.elastic.co/t/how-do-i-use-variables-in-yml-files/73237/3 "2017-02-28T09:31:35Z")

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