Commands & Use Cases

About

This page provides commonly used Docker commands organized by real-world scenarios. It serves as a quick reference for tasks such as managing images, containers, volumes, and performing system cleanups. Each command is explained with its purpose to help streamline day-to-day Docker usage.

Docker Image

List all the images

To list all the docker images available:

docker images

Remove Dangling Images

To remove Docker images with the tag <none>, we can use the following command in our terminal or command prompt:

docker rmi $(docker images -f "dangling=true" -q)

This command first lists all dangling images (images without a tag) using docker images -f "dangling=true" -q, then removes them using docker rmi

Back up Specific Docker images

If we want to back up our Docker images to our local system, we can use the docker save command to export the images to a tar archive file.

1. List all the images we want to back up:

docker images

1. Identify the image IDs or names we want to back up.

2. Use the docker save command to export the images to a tar archive. We can specify multiple images by separating them with spaces:

docker save -o backup.tar IMAGE_ID_1 IMAGE_ID_2 ...

Replace IMAGE_ID_1, IMAGE_ID_2, etc., with the IDs or names of the images we want to back up.

For example, if we want to back up two images with IDs 123abc and 456def, we would run:

docker save -o backup.tar 123abc 456def

This command will create a file named backup.tar containing the specified Docker images.

After creating the backup, we can transfer the backup.tar file to our desired location for safekeeping.

Note: The docker save command exports Docker images without preserving their tags.

If we want to retain the tags along with the images, we can use a combination of docker save and docker inspect commands.

1. List all the images we want to back up:

docker images

1. Identify the image IDs or names we want to back up.

2. Use the docker inspect command to get the tags associated with the images:

docker inspect --format='{{.Id}} {{.RepoTags}}' IMAGE_ID_1 IMAGE_ID_2 ...

Replace IMAGE_ID_1, IMAGE_ID_2, etc., with the IDs or names of the images we want to back up.

1. Combine the docker save and docker inspect commands to export the images with their tags:

docker inspect --format='{{.Id}} {{.RepoTags}}' IMAGE_ID_1 IMAGE_ID_2 ... | \
    awk '{print $1,$2}' | \
    xargs -n2 sh -c 'docker save -o backup_${1//\//_}_${2//:/_}.tar $0:$1' 

This command will create tar files with names like backup_REPOSITORY_TAG.tar for each image, preserving both repository and tag information.

Replace IMAGE_ID_1, IMAGE_ID_2, etc., with the IDs or names of the images we want to back up.