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slug: /1222/core-actions-reference
displayed_sidebar: '0.2'
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# Core Actions Reference

Core Actions are primitives implemented by the Dagger Engine itself. They can be combined into higher-level composite actions. Their definitions can be imported in the `dagger.io/dagger/core` package.

For more information about Dagger Actions, see [Dagger Actions](../core-concepts/1221-action.md).

The following core actions are available:

## Core Actions related to filesystem trees

| Definition   | File                                                                                    | Description                                                           |
| :----------- | :-------------------------------------------------------------------------------------- | :-------------------------------------------------------------------- |
| `#Copy`      | [fs.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/fs.cue) | Copy files between two filesystem trees                               |
| `#Diff`      | [fs.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/fs.cue) | Extract the difference between two filesystems as its own file system |
| `#Merge`     | [fs.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/fs.cue) | Merge multiple filesystem trees                                       |
| `#Mkdir`     | [fs.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/fs.cue) | Create a directory in a filesystem tree                               |
| `#ReadFile`  | [fs.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/fs.cue) | Read a file from a filesystem tree                                    |
| `#Source`    | [fs.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/fs.cue) | Access the source for the current CUE package                         |
| `#Subdir`    | [fs.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/fs.cue) | Read a subdirectory from a filesystem tree                            |
| `#WriteFile` | [fs.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/fs.cue) | Write a file to a filesystem tree                                     |

## Core Actions related to secrets

| Definition      | File                                                                                              | Description                                              |
| :-------------- | :------------------------------------------------------------------------------------------------ | :------------------------------------------------------- |
| `#DecodeSecret` | [secrets.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/secrets.cue) | Decode a secret without leaking its contents             |
| `#NewSecret`    | [secrets.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/secrets.cue) | Create a new a secret from a filesystem tree             |
| `#TrimSecret`   | [secrets.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/secrets.cue) | Trim leading and trailing space characters from a secret |

## Core Actions related to containers

| Definition    | File                                                                                          | Description                                        |
| :------------ | :-------------------------------------------------------------------------------------------- | :------------------------------------------------- |
| `#Dockerfile` | [image.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/image.cue) | Build a container image using a Dockerfile         |
| `#Exec`       | [exec.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/exec.cue)   | Execute a command in a docker-compatible container |
| `#Export`     | [image.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/image.cue) | Export a docker image as a tar archive             |
| `#Pull`       | [image.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/image.cue) | Download an image from a docker registry           |
| `#Push`       | [image.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/image.cue) | Upload an image to a docker registry               |
| `#Set`        | [image.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/image.cue) | Modify a docker image config                       |

## Core Actions related to remote data sources

| Definition   | File                                                                                        | Description                                    |
| :----------- | :------------------------------------------------------------------------------------------ | :--------------------------------------------- |
| `#GitPull`   | [git.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/git.cue)   | Download a repository from a remote git server |
| `#HTTPFetch` | [http.cue](https://github.com/dagger/dagger/blob/v0.2.4/pkg/dagger.io/dagger/core/http.cue) | Get a file from an HTTP server                 |
