Commands

Commands Table

Command	Description	Usage	Example	More Info
#WORKDIR	Specify the working directory of the project in the docker file system	WORKDIR <folderPath>	WORKDIR /app	null
#CMD	The initial command to execute when the container is build, this command executes only when the container is up	CMD ["cmd1", "cmd2"]	CMD ["node", "app.js"]	null
#RUN	This is another way to specify the commands to execute while building the image, this command executes when the image is being build	RUN <command>	RUN npm install	null
docker #build	#Docker command to build specific images	docker build <pathToDockerfile>	docker build .	#docker_build
docker run	#Docker command to run the image specified alias start the container	docker run <imageID>	docker run node	#docker_run
docker ps	#Docker command to list all the containers that are currently up and running	docker ps	docker ps	#docker_ps
docker stop	#Docker command to stop the running container	docker stop <containerID>	docker stop node	null
docker logs	#Docker command to see the logs of the container	docker logs <containerID>	docker logs node	null
docker inspect	#Docker command to display information about the images and containers	docker container inspect <containerID>	docker container inspect explainlike5/users-app	#docker_inspect
docker cp	#Docker command to copy files from container/image to local system	docker cp <source> <dest>	docker cp <Local_rel_path> <contID>:<path_in_container_fileSystem>	#docker_cp

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Info

For all docker commands where ID can be used, you dont always have to copy/write the full id

You can also just use the first few characters - just enough to have a unique identifier from the containers that you have

All the containers generated will be virtualized from your host system

Most of the images have #docker_run command in interactive mode But the #docker_start command runs the process in background

You can ==name== docker container using the ==--name== tag in the #docker_run command

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#CMD vs #RUN

Consider an example of #NodeJs application, we want to run the server only when the container is up not every time the image is created hence we use #CMD to specify the commands to execute them when the container is up, But for that image/application we require npm modules in our code as dependencies, to get all the #npm_modules in our code, we execute the #RUN command to execute the command every time the image is build

#CMD is little bit similar to #GRUB bootloader system in operating systems

#docker_build

1. This creates a new docker image with a image id hash number specific to that image

2. We can add custom names to our image using ==-t== or ==--tag== flag

#docker_run

1. ==-p== (port) flag

   1. this flag is used to expose the application to host system from the docker engine

   2. usage: -p <ExposedPort>:<InternalDockerPort>

   3. this exposed port is from the local system

   4. InternalDockerPort is from which port to connect to in the docker engine

2. If you dont have that image specified in the command locally in your system then docker reaches docker hub and searches for this image and downloads it for you then it fires up the container

3. To interact with the container example node container you have to use the ==-it== flag along with the command

#docker_inspect

1. you can inspect images also using the ==docker images inspect== command

#docker_cp

1. This command can be replaced by [[Volumes#Bind Mounts]]

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#Important_Docker

-> To execute the system command, we can use the #CMD command in the [[Dockerfile]], if you don't specify a #CMD , the CMD of the base image will be executed.

With no base image and no #CMD , you will get an error

You cannot remove a running container, to delete that particular container you need to stop the container and then remove the container

Similarly you cannot remove the images that are being used by containers that are up and running, for that you need to stop the container then you can delete the image