Some useful docker commands
docker pull ubuntu:latest
docker start CONTAINER_ID
create a container from image and access it's terminal
docker run -it --entrypoint "/bin/bash" ubuntu
access terminal from a running container
docker exec -it CONTAINER_ID bash
example setting environment variables
docker run --name postgres -e POSTGRES_PASSWORD=123456 -d -p 5432:5432 postgres
docker cp file.txt CONTAINER_ID:/tmp/
create image from a container
docker commit CONTAINER_ID
docker tag CONTAINER_ID tag_name
docker commit CONTAINER_ID tag_name
docker save image_name -o file.tar