> ## Documentation Index
> Fetch the complete documentation index at: https://e2b.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Environment variables

This page covers how to set and use environment variables in a sandbox, and default environment variables inside the sandbox.

## Default environment variables

### Knowing if you are inside a sandbox

Sometimes it's useful to know if the code is running inside a sandbox. Upon creating a sandbox, useful sandbox metadata is set as environment variables for commands:

* `E2B_SANDBOX` is set to `true` for processes to know if they are inside our VM.
* `E2B_SANDBOX_ID` to know the ID of the sandbox.
* `E2B_TEAM_ID` to know the team ID that created the sandbox.
* `E2B_TEMPLATE_ID` to know what template was used for the current sandbox.

You can try it out by running the following code in the sandbox:

<CodeGroup>
  ```js JavaScript & TypeScript theme={"theme":{"light":"github-light","dark":"github-dark-default"}}
  const sandbox = await Sandbox.create()
  const result = await sandbox.commands.run('echo $E2B_SANDBOX_ID')
  ```

  ```python Python theme={"theme":{"light":"github-light","dark":"github-dark-default"}}
  sandbox = Sandbox.create()
  result = sandbox.commands.run("echo $E2B_SANDBOX_ID")
  ```
</CodeGroup>

<Note>
  These default environment variables are only accessible via the SDK, when using the CLI you can find them in the form of dot files in the `/run/e2b/` dir:

  ```sh theme={"theme":{"light":"github-light","dark":"github-dark-default"}}
  user@e2b:~$ ls -a /run/e2b/
  .E2B_SANDBOX  .E2B_SANDBOX_ID  .E2B_TEAM_ID  .E2B_TEMPLATE_ID
  ```
</Note>

***

## Setting environment variables

There are 3 ways to set environment variables in a sandbox:

1. [Global environment variables when creating the sandbox](/docs/sandbox/environment-variables#1-global-environment-variables).
2. [When running code in the sandbox](/docs/sandbox/environment-variables#2-setting-environment-variables-when-running-code).
3. [When running commands in the sandbox](/docs/sandbox/environment-variables#3-setting-environment-variables-when-running-commands).

### 1. Global environment variables

You can set global environment variables when creating a sandbox.

<CodeGroup>
  ```js JavaScript & TypeScript highlight={2-4} theme={"theme":{"light":"github-light","dark":"github-dark-default"}}
  const sandbox = await Sandbox.create({
    envs: {
      MY_VAR: 'my_value',
    },
  })
  ```

  ```python Python highlight={2-4} theme={"theme":{"light":"github-light","dark":"github-dark-default"}}
  sandbox = Sandbox.create(
    envs={
      'MY_VAR': 'my_value',
    },
  )
  ```
</CodeGroup>

### 2. Setting environment variables when running code

You can set environment variables for specific code execution call in the sandbox.

<Note>
  * These environment variables are scoped to the command but are not private in the OS.
  * If you had a global environment variable with the same name, it will be overridden only for the command.
</Note>

<CodeGroup>
  ```js JavaScript & TypeScript highlight={3-5} theme={"theme":{"light":"github-light","dark":"github-dark-default"}}
  const sandbox = await Sandbox.create()
  const result = await sandbox.runCode('import os; print(os.environ.get("MY_VAR"))', {
    envs: {
      MY_VAR: 'my_value',
    },
  })
  ```

  ```python Python highlight={4-6} theme={"theme":{"light":"github-light","dark":"github-dark-default"}}
  sandbox = Sandbox.create()
  result = sandbox.run_code(
      'import os; print(os.environ.get("MY_VAR"))',
      envs={
          'MY_VAR': 'my_value'
      }
  )
  ```
</CodeGroup>

### 3. Setting environment variables when running commands

You can set environment variables for specific command execution in the sandbox.

<Note>
  * These environment variables are scoped to the command but are not private in the OS.
  * If you had a global environment variable with the same name, it will be overridden only for the command.
</Note>

<CodeGroup>
  ```js JavaScript & TypeScript highlight={3-5} theme={"theme":{"light":"github-light","dark":"github-dark-default"}}
  const sandbox = await Sandbox.create()
  sandbox.commands.run('echo $MY_VAR', {
    envs: {
      MY_VAR: '123',
    },
  })
  ```

  ```python Python highlight={4-6} theme={"theme":{"light":"github-light","dark":"github-dark-default"}}
  sandbox = Sandbox.create()
  sandbox.commands.run(
      'echo $MY_VAR',
      envs={
          'MY_VAR': '123'
      }
  )
  ```
</CodeGroup>