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

# zb update

> Update package formula cache

The `zb update` command clears the locally cached formula definitions, forcing zerobrew to fetch the latest package metadata on the next operation.

## Usage

```bash theme={null}
zb update
```

## Description

This command clears zerobrew's API cache, which stores formula information. After running `zb update`, the next time you check for outdated packages or install new software, zerobrew will fetch fresh metadata from the remote repository.

Unlike Homebrew's `brew update` which updates the tap repository itself, `zb update` simply clears the cached formula entries to ensure you get the latest information.

## Examples

Update the formula cache:

```bash theme={null}
zb update
```

After updating, check which packages have new versions available:

```bash theme={null}
zb update
zb outdated
```

## Output

When cache entries are cleared:

```
==> Cleared 42 cached formula entries.
Run `zb outdated` to check for updates.
```

When the cache is already empty:

```
==> No cached entries to clear.
Run `zb outdated` to check for updates.
```

## Related Commands

* [zb outdated](/commands/outdated) - List packages with available updates
* [zb install](/commands/install) - Install or upgrade packages