🐧 Linux Basics

Common Commands

pwd                  # show current directory
ls -lh               # list files and folders
cd /path/to/dir      # change directory
cd ..                # go one level up

File & Folder Management

mkdir backups                # create a new folder
rmdir empty_folder           # remove empty folder
rm file.txt                  # delete file
rm -r old_data               # delete folder with contents
cp source.txt /tmp/          # copy file
mv oldname.txt newname.txt   # rename or move file

Editing Files

nano config.toml   # simple text editor
vim config.toml    # advanced editor (ESC :wq — save & exit)

System Commands

top          # show active processes
ps aux       # list all processes
kill <PID>   # stop a process
df -h        # check disk usage
free -h      # check memory usage

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Node.js Reference

Installation & Setup

# install Node.js via nvm
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/master/install.sh | bash
nvm install --lts
node -v
npm -v

Create a Project

mkdir myproject
cd myproject
npm init    # initialize package.json

Install Packages

npm install express               # regular dependency
npm install nodemon --save-dev    # development dependency

Run Project

node app.js     # run directly
npm start       # run via npm (if defined in package.json)

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Docker Essentials

Basic Commands

docker --version          # check Docker version
docker pull <image>       # pull image
docker images             # list images
docker rmi <image>        # remove image
docker run <image>        # run container
docker ps                 # show active containers
docker ps -a              # show all containers
docker stop <id>          # stop container
docker rm <id>            # remove container

Example Dockerfile

FROM node:18-alpine
WORKDIR /app
COPY . .
RUN npm install
CMD ["node", "app.js"]

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Docker Cleanup & Removal

Remove Docker (Ubuntu/Debian)

sudo systemctl stop docker                 # stop Docker service
sudo apt-get purge -y docker-ce docker-ce-cli containerd.io   # remove Docker packages
sudo rm -rf /var/lib/docker                # remove Docker data
sudo rm -rf /etc/docker                    # remove config files
sudo apt-get autoremove -y                 # remove dependencies
sudo apt-get autoclean                     # clean package cache

Clean up Docker containers and images

sudo docker system prune -a --volumes      # remove unused containers, images, and volumes

Clear system cache

rm -rf /root/.cache/*                      # clear root cache

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🧭 Conclusion

This quick reference guide provides essential commands for Linux, Node.js, and Docker — everything a validator or system administrator needs for setup, management, and automation in production environments.