# setEnv

Description: setEnv cheatcode documentation

Note: This document was authored using MDX

  Source: https://github.com/NomicFoundation/hardhat-website/tree/main/src/content/docs/docs/reference/cheatcodes/External/set-env.mdx

  Components used in this page:
    - :::note: An informational callout block. Supports custom title `:::note[Title]` and icon `:::note{icon="name"}` syntax.

{/* This document contains content copied/adapted from the Foundry Book (MIT licensed). See LICENSE in the parent directory. */}

### Signature

```solidity
function setEnv(string calldata key, string calldata value) external;
```

### Description

Set an environment variable `key=value`.

:::note
Environment variables set by a process are only accessible by itself and its child
processes. Thus, calling `setEnv` will only modify environment variables of the currently running
process, and won't affect the shell (parent process), i.e., they won't persist after the
current process exits.
:::

### Tips

- The environment variable key can't be empty.
- The environment variable key can't contain the equal sign `=` or the NUL character `\0`.
- The environment variable value can't contain the NUL character `\0`.

### Examples

```solidity
string memory key = "hello";
string memory val = "world";
cheats.setEnv(key, val);
```