A Pocket Guide to Docker Commands and Container Management

Docker has revolutionized the way applications are developed, deployed, and managed. It provides a lightweight and portable environment for running containers, which are self-contained instances of an application and its dependencies. Docker commands offer a powerful means to manage and interact with these containers.

Updating and Listing Container Images

The provided Bash commands demonstrate the process of updating and listing Docker container images.

sudo docker container run -it centos:7 bash
sudo yum -y update
ls -l

This script first creates a new container based on the centos:7 image. Inside the container, it updates the system packages using the yum command. Finally, it lists the contents of the current directory.

sudo docker cantainer run -it rockylinux:9 bash
dnf install sudo
sudo dnf update -y

Similar to the previous example, this script creates a container based on the rockylinux:9 image. However, instead of using yum, it utilizes the dnf package manager for updating and installing software.

Creating and Managing Files Within a Container

The following commands illustrate file creation and management within a container.

echo "We are here" > example.txt
ls -l
cat example.txt
exit

This script creates a file named example.txt and writes the text "We are here" to it. Subsequently, it lists the contents of the current directory, displays the file content using cat, and exits the container.

Monitoring and Interacting with Running Containers

The provided commands demonstrate how to monitor and interact with running containers.

sudo docker ps
sudo docker ps -a
sudo docker container run -it rockylinux:9 bash
ls -l
exit
sudo docker ps -a
sudo docker container start container_id
sudo docker ps
sudo docker container exec container_id ps -ef
sudo docker container exec container_id bash
sudo docker container exec -it container_id bash
ls -l
cat example.txt

This script starts by listing all running containers using docker ps. It then lists all containers, including stopped ones, using docker ps -a. Next, it creates and enters a new container based on the rockylinux:9 image. It then lists the contents of the directory, exits the container, and lists all containers again. Subsequently, it starts a specific container using docker container start container~id~, lists containers again, and executes the ps -ef command within the container to view its processes. Finally, it enters the container interactively using docker container exec -it container~id~ bash and lists the contents of the directory, displaying the file content using cat.

These commands demonstrate the versatility of Docker commands in managing and interacting with containers. They provide insights into updating container images, creating and managing files within containers, and monitoring and interacting with running containers.