Docker Commands

Question 1

What is “docker run” command?

Answer 1

The Docker run command is used
to run a container from an image. Running the docker run nginx command will run an instance of the nginx application on the Docker host if it already exists. If the image is not present on the host, it will go out to Docker hub and pull that image down.

Question 2

What is the “docker ps” command?

Answer 2

The docker ps command lists all running containers and some basic information about them such as the container lD., the name of the image we used to run the containers, the current status, and the name of the container.

Question 3

How is the ID and name created for the containers in docker?

Answer 3

Each container automatically gets a random lD. and name created for it by Docker

Question 4

what is “docker stop” command?

Answer 4

To stop a running container, use the docker stop command, but you must provide either the container l.D. or the container name in the stop command. If you’re not sure of the name, run the docker ps command to get it.

Question 5

What is the “docker rm” command?

Answer 5

Use the docker rm command to remove a stopped or exited container permanently.

Question 6

How long does a container live?

Answer 6

Container only lives or is alive as long as the process running inside it.
Once the task is complete, the container exits. A container only lives as long as the process inside it is alive.
If the web service inside the container is stopped or crashed, then the container exits.

Question 7

What command to use if you just want the image, but do not want to run a container using that image?

Answer 7

docker pull <image-name>
eg. docker pull ubuntu</image-name>

Question 8

Docker command to remove an image?

Answer 8

docker rmi <image-name></image-name>

Question 9

what does “docker images” command do?

Answer 9

Lists all the downloaded or locally available images

Question 10

What are the two modes of running the “docker run” command

Answer 10

1. Foreground or attached mode
2. Detached mode

Question 11

which is the default docker repository which has the official images?

Answer 11

library

Question 12

what is the difference between exec and -it

Answer 12

docker exec is used to execute a command in a container and get the output in the std out.

-it option is used with docker run command and is used to get into the bash or get inside the container

Question 13

What is docker run in detached mode

Answer 13

use that using -d option with docker run. That is used to have the docker container running in the background. You can get back to the prompt to run other commands in detached mode. In attached mode you will be attache dto the container not coming out of prompt to enter any other commands

Question 14

Command to force kill a docker container?

Answer 14

docker stop <container-name></container-name>

Question 15

command to remove a stopped or exited container permanently

Answer 15

docker rm <container-name></container-name>

Question 16

what option to use in docker run command when you want to name the container?

Answer 16

–name
The order is important. eg
docker run –name webapp nginx:1.14