This is the AWS CDK v2 Developer Guide. The older CDK v1 entered maintenance on June 1, 2022 and ended support on June 1, 2023.

# Get a value from an environment variable
<a name="get-env-var"></a>

To get the value of an environment variable, use code like the following. This code gets the value of the environment variable `amzn-s3-demo-bucket`.

**Example**  

```
// Sets bucket_name to undefined if environment variable not set
var bucket_name = process.env.amzn-s3-demo-bucket;

// Sets bucket_name to a default if env var doesn't exist
var bucket_name = process.env.amzn-s3-demo-bucket || "DefaultName";
```

```
// Sets bucket_name to undefined if environment variable not set
var bucket_name = process.env.amzn-s3-demo-bucket;

// Sets bucket_name to a default if env var doesn't exist
var bucket_name = process.env.amzn-s3-demo-bucket || "DefaultName";
```

```
import os

# Raises KeyError if environment variable doesn't exist
bucket_name = os.environ["amzn-s3-demo-bucket"]

# Sets bucket_name to None if environment variable doesn't exist
bucket_name = os.getenv("amzn-s3-demo-bucket")

# Sets bucket_name to a default if env var doesn't exist
bucket_name = os.getenv("amzn-s3-demo-bucket", "DefaultName")
```

```
// Sets bucketName to null if environment variable doesn't exist
String bucketName = System.getenv("amzn-s3-demo-bucket");

// Sets bucketName to a default if env var doesn't exist
String bucketName = System.getenv("amzn-s3-demo-bucket");
if (bucketName == null) bucketName = "DefaultName";
```

```
using System;

// Sets bucket name to null if environment variable doesn't exist
string bucketName = Environment.GetEnvironmentVariable("amzn-s3-demo-bucket");

// Sets bucket_name to a default if env var doesn't exist
string bucketName = Environment.GetEnvironmentVariable("amzn-s3-demo-bucket") ?? "DefaultName";
```