Category: Docker

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Some Docker commands

Create an image linux centos from docker repository : docker run -it centos

and run into a container

docker run -i -t centos

OR

create your custom centos image like this:

  1. create a folder mkdir centos1, and go inside cd centos1
  2. download the image from here into the folder centos1
  3. create the file Dockerfile into the folder centos1

FROM scratch
ADD CentOS-7-20140625-x86_64-docker_01.img.tar.xz /
LABEL name=”CentOS Base Image” \
vendor=”CentOS” \
license=”GPLv2″ \
build-date=”20190426″
CMD [“/bin/bash”]

4. run this command into the folder centos1 : docker build -t name_of_image .

5. run the command for view list of your images : docker images

6. run this command to enter into the image : docker run -it name_of_image

  1. To save an image to any file path or shared NFS place see the following example.Get the image id by doing: 
    sudo docker images

    Say you have an image with id “matrix-data”.

    Save the image with id:

    sudo docker save -o /home/matrix/matrix-data.tar matrix-data

    Copy the image from the path to any host. Now import to your local Docker installation using:

    sudo docker load -i <path to copied image file>

Remove images

docker image ls

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The output should look something like this:

REPOSITORY              TAG                 IMAGE ID            CREATED             SIZE
centos                  latest              75835a67d134        7 days ago          200MB
ubuntu                  latest              2a4cca5ac898        2 months ago        111MB
linuxize/fedora         latest              a45d6dca3361        3 months ago        311MB
java                    8-jre               e44d62cf8862        3 months ago        311MB

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Once you’ve located the images you want to remove, pass their IMAGE ID to the docker image rm command. For example to remove the first two images listed in the output above run:

docker image rm 75835a67d134 2a4cca5ac898

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If you get an error similar to the following, it means that the image is used by an existing container. To remove the image you will have to remove the container first.

To remove one or more Docker images use the docker container rmcommand followed by the ID of the containers you want to remove.

You can get a list of all active and inactive containers by passing the -a flag to the docker container ls command:

docker container ls -a

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The output should look something like this:

CONTAINER ID        IMAGE                   COMMAND                  CREATED             STATUS                      PORTS               NAMES
cc3f2ff51cab        centos                  "/bin/bash"              2 months ago        Created                                         competent_nightingale
cd20b396a061        solita/ubuntu-systemd   "/bin/bash -c 'exec …"   2 months ago        Exited (137) 2 months ago                       systemd
fb62432cf3c1        ubuntu                  "/bin/bash"              3 months ago        Exited (130) 3 months ago                       jolly_mirzakhani

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Once you know the CONTAINER ID of the containers you want to delete, pass it to the docker container rm command. For example to remove the first two containers listed in the output above run:

docker container rm cc3f2ff51cab cd20b396a061

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If you get an error similar to the following, it means that the container is running. You’ll need to stop the container before removing it.