> For the complete documentation index, see [llms.txt](https://ret2basic.gitbook.io/ctfnote/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ret2basic.gitbook.io/ctfnote/web3-security-research/foundry/remappings.md).

# Remappings

{% embed url="<https://youtu.be/7DK75j8csTA>" %}

## Solmate (forge remappings)

Install solmate:

```bash
forge install rari-capital/solmate
```

Create an ERC20 contract:

```solidity
pragma solidity ^0.8.17;

import "solmate/tokens/ERC20.sol";

contract Token is ERC20("name", "symbol", 18) {}
```

Build:

```bash
forge build
```

See what libraries have been installed:

```bash
$ forge remappings

ds-test/=lib/forge-std/lib/ds-test/src/
forge-std/=lib/forge-std/src/
solmate/=lib/solmate/src/
```

Here `solmate` is remapped to `lib/solmate/src/`.

## OpenZeppelin Contracts (remappings.txt)

Some libraries, such as OpenZeppelin contracts, should be installed via npm:

```bash
mkdir node_modules && npm i @openzeppelin/contracts
```

We run `mkdir` first because node modules can be install locally or globally. Reference:

{% embed url="<https://stackoverflow.com/questions/14032160/npm-install-module-in-current-directory>" %}

In contract, import OpenZeppelin `Ownable`:

```solidity
import "@openzeppelin/contracts/access/Ownable.sol";
```

We have to create a `remappings.txt` file for this import statement to make sense:

```
@openzeppelin/=node_modules/@openzeppelin
```

Update our contract:

```solidity
pragma solidity ^0.8.17;

import "solmate/tokens/ERC20.sol";

contract Token is ERC20("name", "symbol", 18) {}

import "@openzeppelin/contracts/access/Ownable.sol";

contract TestOz is Ownable {}
```

Build it:

```bash
forge build
```

<figure><img src="/files/7jYRq5mcxhoGE7DF5hCy" alt=""><figcaption><p>Build succeeded</p></figcaption></figure>


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