> For the complete documentation index, see [llms.txt](https://startower.gitbook.io/star-tower-chain/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://startower.gitbook.io/star-tower-chain/untitled/env-variables.md).

# ENV Variables

StarTower uses ENVs for setting hundreds of different parameters. Please see the various sections for ENV names, descriptions, default values and versioning.

* Backend ENVs: Common
* Backend ENVs: Chain Specific
* Backend ENVs: Integrations
* Frontend ENVs: Common

{% hint style="info" %}
You will find deprecated ENV vars on the Deprecated ENV Variables page.
{% endhint %}

### Set ENV Variables with CLI <a href="#set-env-variables-with-cli" id="set-env-variables-with-cli"></a>

Use the export command to set variables. For example:

Copy

```
$ export ETHEREUM_JSONRPC_VARIANT=nethermind
$ export COIN=POA
$ export NETWORK=POA
```

### Required ENV variables <a href="#required-env-variables" id="required-env-variables"></a>

Please see the Backend ENVs page for details. Required variables are located in the General Management section and marked with a ✅

### Time format <a href="#time-format" id="time-format"></a>

Can be set in format `1h` for 1 hour, `1m` for 1 minute, `1s` or `1` for 1 second, `1ms` for 1 millisecond

{% hint style="info" %}
*Note*: **Before release 5.1.2, all environment variables of time format supported only integers in seconds (without dimensions) as values.**
{% endhint %}