# atmos toolchain aliases

List effective built-in and configured tool aliases, with table, JSON, or YAML output.

## Usage

```shell
atmos toolchain aliases [--format table|json|yaml]
```

List the effective tool aliases from built-in defaults and the merged Atmos configuration. Configured aliases override built-in aliases with the same name. The default table is sorted by alias name.

The command displays each alias target as defined. It does not resolve alias chains, search registries, install tools, or modify toolchain files.

## Examples

Configure aliases in `atmos.yaml`:

```yaml
toolchain:
  aliases:
    tf: hashicorp/terraform
    infra: opentofu/opentofu
```

Inspect the effective aliases:

```shell
atmos toolchain aliases
atmos toolchain aliases --format=json
atmos toolchain aliases --format=yaml
```

JSON and YAML output are mappings from alias names to their targets, including built-in aliases. For example, the configuration above adds `infra` and sets `tf` in that mapping.

## Flags

| Flag | Description | Default |
|------|-------------|---------|
| `--format`, `-f` | Output format: `table`, `json`, or `yaml` | `table` |

Set `ATMOS_TOOLCHAIN_ALIASES_FORMAT` to select the default output format. An explicit flag takes precedence over the environment variable.

See [Toolchain aliases configuration](/cli/configuration/toolchain/aliases) for configuration examples and resolution behavior.