mirror of https://github.com/docker/cli.git
255 lines
9.2 KiB
Markdown
255 lines
9.2 KiB
Markdown
---
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title: "pull"
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description: "The pull command description and usage"
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keywords: "pull, image, hub, docker"
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---
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<!-- This file is maintained within the docker/cli Github
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# pull
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```markdown
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Usage: docker pull [OPTIONS] NAME[:TAG|@DIGEST]
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Pull an image or a repository from a registry
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Options:
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-a, --all-tags Download all tagged images in the repository
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--disable-content-trust Skip image verification (default true)
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--help Print usage
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```
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## Description
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Most of your images will be created on top of a base image from the
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[Docker Hub](https://hub.docker.com) registry.
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[Docker Hub](https://hub.docker.com) contains many pre-built images that you
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can `pull` and try without needing to define and configure your own.
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To download a particular image, or set of images (i.e., a repository),
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use `docker pull`.
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### Proxy configuration
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If you are behind an HTTP proxy server, for example in corporate settings,
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before open a connect to registry, you may need to configure the Docker
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daemon's proxy settings, using the `HTTP_PROXY`, `HTTPS_PROXY`, and `NO_PROXY`
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environment variables. To set these environment variables on a host using
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`systemd`, refer to the [control and configure Docker with systemd](https://docs.docker.com/engine/admin/systemd/#http-proxy)
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for variables configuration.
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### Concurrent downloads
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By default the Docker daemon will pull three layers of an image at a time.
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If you are on a low bandwidth connection this may cause timeout issues and you may want to lower
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this via the `--max-concurrent-downloads` daemon option. See the
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[daemon documentation](dockerd.md) for more details.
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## Examples
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### Pull an image from Docker Hub
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To download a particular image, or set of images (i.e., a repository), use
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`docker pull`. If no tag is provided, Docker Engine uses the `:latest` tag as a
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default. This command pulls the `debian:latest` image:
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```bash
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$ docker pull debian
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Using default tag: latest
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latest: Pulling from library/debian
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fdd5d7827f33: Pull complete
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a3ed95caeb02: Pull complete
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Digest: sha256:e7d38b3517548a1c71e41bffe9c8ae6d6d29546ce46bf62159837aad072c90aa
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Status: Downloaded newer image for debian:latest
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```
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Docker images can consist of multiple layers. In the example above, the image
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consists of two layers; `fdd5d7827f33` and `a3ed95caeb02`.
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Layers can be reused by images. For example, the `debian:jessie` image shares
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both layers with `debian:latest`. Pulling the `debian:jessie` image therefore
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only pulls its metadata, but not its layers, because all layers are already
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present locally:
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```bash
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$ docker pull debian:jessie
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jessie: Pulling from library/debian
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fdd5d7827f33: Already exists
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a3ed95caeb02: Already exists
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Digest: sha256:a9c958be96d7d40df920e7041608f2f017af81800ca5ad23e327bc402626b58e
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Status: Downloaded newer image for debian:jessie
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```
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To see which images are present locally, use the [`docker images`](images.md)
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command:
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```bash
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$ docker images
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REPOSITORY TAG IMAGE ID CREATED SIZE
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debian jessie f50f9524513f 5 days ago 125.1 MB
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debian latest f50f9524513f 5 days ago 125.1 MB
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```
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Docker uses a content-addressable image store, and the image ID is a SHA256
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digest covering the image's configuration and layers. In the example above,
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`debian:jessie` and `debian:latest` have the same image ID because they are
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actually the *same* image tagged with different names. Because they are the
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same image, their layers are stored only once and do not consume extra disk
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space.
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For more information about images, layers, and the content-addressable store,
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refer to [understand images, containers, and storage drivers](https://docs.docker.com/engine/userguide/storagedriver/imagesandcontainers/).
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### Pull an image by digest (immutable identifier)
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So far, you've pulled images by their name (and "tag"). Using names and tags is
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a convenient way to work with images. When using tags, you can `docker pull` an
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image again to make sure you have the most up-to-date version of that image.
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For example, `docker pull ubuntu:14.04` pulls the latest version of the Ubuntu
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14.04 image.
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In some cases you don't want images to be updated to newer versions, but prefer
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to use a fixed version of an image. Docker enables you to pull an image by its
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*digest*. When pulling an image by digest, you specify *exactly* which version
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of an image to pull. Doing so, allows you to "pin" an image to that version,
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and guarantee that the image you're using is always the same.
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To know the digest of an image, pull the image first. Let's pull the latest
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`ubuntu:14.04` image from Docker Hub:
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```bash
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$ docker pull ubuntu:14.04
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14.04: Pulling from library/ubuntu
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5a132a7e7af1: Pull complete
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fd2731e4c50c: Pull complete
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28a2f68d1120: Pull complete
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a3ed95caeb02: Pull complete
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Digest: sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2
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Status: Downloaded newer image for ubuntu:14.04
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```
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Docker prints the digest of the image after the pull has finished. In the example
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above, the digest of the image is:
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sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2
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Docker also prints the digest of an image when *pushing* to a registry. This
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may be useful if you want to pin to a version of the image you just pushed.
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A digest takes the place of the tag when pulling an image, for example, to
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pull the above image by digest, run the following command:
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```bash
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$ docker pull ubuntu@sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2
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sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2: Pulling from library/ubuntu
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5a132a7e7af1: Already exists
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fd2731e4c50c: Already exists
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28a2f68d1120: Already exists
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a3ed95caeb02: Already exists
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Digest: sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2
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Status: Downloaded newer image for ubuntu@sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2
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```
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Digest can also be used in the `FROM` of a Dockerfile, for example:
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```Dockerfile
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FROM ubuntu@sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2
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MAINTAINER some maintainer <maintainer@example.com>
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```
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> **Note**: Using this feature "pins" an image to a specific version in time.
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> Docker will therefore not pull updated versions of an image, which may include
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> security updates. If you want to pull an updated image, you need to change the
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> digest accordingly.
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### Pull from a different registry
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By default, `docker pull` pulls images from [Docker Hub](https://hub.docker.com). It is also possible to
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manually specify the path of a registry to pull from. For example, if you have
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set up a local registry, you can specify its path to pull from it. A registry
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path is similar to a URL, but does not contain a protocol specifier (`https://`).
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The following command pulls the `testing/test-image` image from a local registry
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listening on port 5000 (`myregistry.local:5000`):
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```bash
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$ docker pull myregistry.local:5000/testing/test-image
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```
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Registry credentials are managed by [docker login](login.md).
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Docker uses the `https://` protocol to communicate with a registry, unless the
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registry is allowed to be accessed over an insecure connection. Refer to the
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[insecure registries](dockerd.md#insecure-registries) section for more information.
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### Pull a repository with multiple images
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By default, `docker pull` pulls a *single* image from the registry. A repository
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can contain multiple images. To pull all images from a repository, provide the
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`-a` (or `--all-tags`) option when using `docker pull`.
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This command pulls all images from the `fedora` repository:
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```bash
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$ docker pull --all-tags fedora
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Pulling repository fedora
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ad57ef8d78d7: Download complete
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105182bb5e8b: Download complete
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511136ea3c5a: Download complete
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73bd853d2ea5: Download complete
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....
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Status: Downloaded newer image for fedora
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```
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After the pull has completed use the `docker images` command to see the
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images that were pulled. The example below shows all the `fedora` images
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that are present locally:
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```bash
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$ docker images fedora
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REPOSITORY TAG IMAGE ID CREATED SIZE
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fedora rawhide ad57ef8d78d7 5 days ago 359.3 MB
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fedora 20 105182bb5e8b 5 days ago 372.7 MB
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fedora heisenbug 105182bb5e8b 5 days ago 372.7 MB
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fedora latest 105182bb5e8b 5 days ago 372.7 MB
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```
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### Cancel a pull
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Killing the `docker pull` process, for example by pressing `CTRL-c` while it is
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running in a terminal, will terminate the pull operation.
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```bash
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$ docker pull fedora
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Using default tag: latest
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latest: Pulling from library/fedora
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a3ed95caeb02: Pulling fs layer
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236608c7b546: Pulling fs layer
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^C
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```
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> **Note**: Technically, the Engine terminates a pull operation when the
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> connection between the Docker Engine daemon and the Docker Engine client
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> initiating the pull is lost. If the connection with the Engine daemon is
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> lost for other reasons than a manual interaction, the pull is also aborted.
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