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_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:

const sandbox = await Sandbox.create()
const result = await sandbox.commands.run('echo $E2B_SANDBOX_ID')

user@e2b:~$ ls -a /run/e2b/
.E2B_SANDBOX  .E2B_SANDBOX_ID  .E2B_TEMPLATE_ID

Setting environment variables

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

1. Global environment variables when creating the sandbox.
2. When running code in the sandbox.
3. When running commands in the sandbox.

1. Global environment variables

You can set global environment variables when creating a sandbox.

const sandbox = await Sandbox.create({
  envs: {
    MY_VAR: 'my_value',
  },
})

2. Setting environment variables when running code

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

const sandbox = await Sandbox.create()
const result = await sandbox.runCode('import os; print(os.environ.get("MY_VAR"))', {
  envs: {
    MY_VAR: 'my_value',
  },
})

3. Setting environment variables when running commands

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

const sandbox = await Sandbox.create()
sandbox.commands.run('echo $MY_VAR', {
  envs: {
    MY_VAR: '123',
  },
})