File and Directory Commands:
ls: List files and directories. Syntax: ls [options] [directory]
cd: Change directory. Syntax: cd [directory]
pwd: Print working directory. Syntax: pwd
mkdir: Create a new directory. Syntax: mkdir [directory]
cp: Copy files or directories. Syntax: cp [options] source destination
mv: Move or rename files/directories. Syntax: mv [options] source destination
rm: Remove/delete files or directories. Syntax: rm [options] file

File Manipulation:
cat: Concatenate and display the content of files. Syntax: cat [file]
nano Text editors to create or edit files. Syntax (nano): nano [file]_
Vim_: Text editors to create or edit files.Syntax (vim): vim [file]
touch: Create an empty file or update timestamp. Syntax: touch [file]

System Information:
uname -a: Display system information. Syntax: uname -a
df -h: Show disk space usage. Syntax: df -h
free -h: Display RAM usage. Syntax: free -h
t_op or htop_: Display running processes. Syntax: top or htop

Debian/Ubuntu:
sudo apt update: Update package lists. Syntax: sudo apt update
sudo apt upgrade: Upgrade installed packages. Syntax: sudo apt upgrade
sudo apt install : Install a new package. Syntax: sudo apt install [package]

Red Hat/Fedora:
sudo yum update: Update packages. Syntax: sudo yum update
sudo yum install: Install a new package. Syntax: sudo yum install [package]

Node.js
node -v: Check Node.js version. Syntax: node -v
npm -v: Check npm version. Syntax: npm -v
npm init: Initialize a new Node.js project. Syntax: npm init
node app.js: Run a Node.js script. Syntax: node [script]

NPM:
npm install : Install a Node.js package.Syntax: npm install [package]
npm install -g : Install a global package.Syntax: npm install -g [package]
npm start: Start the application (as defined in package.json).Syntax: npm start
npm test: Run tests.Syntax: npm test
npm run <script>: Run a custom script.Syntax: npm run [script]

MongoDB Service:
Sudo service mongod start: Start MongoDB service. Syntax: sudo service mongod start
sudo service mongod stop: Stop MongoDB service.Syntax: sudo service mongod stop
sudo service mongod restart: Restart MongoDB service. Syntax: sudo service mongod restart

Mongo Shell:
mongo: Open the MongoDB shell. Syntax: mongo
show dbs: Show available databases.Syntax: show dbs
use <database>: Switch to a specific database.Syntax: use [database]
db.<collection>.find(): Retrieve documents from a collection. Syntax: db.[collection].find()

Repository Management:
git init: Initialize a new Git repository. Syntax: git init
git clone <repository>: Clone a repository. Syntax: git clone [repository]
git add .: Stage all changes for commit.Syntax: git add .
git commit -m “message”: Commit changes with a message. Syntax: git commit -m “message”

Branching:
git branch: List branches.Syntax: git branch
git checkout <branch>: Switch to a different branch.Syntax: git checkout [branch]
git merge <branch>: Merge a branch into the current branch.Syntax: git merge [branch]

Remote Repositories:
git remote add origin <repository>: Add a remote repository. Syntax: git remote add origin [repository]
git push -u origin <branch>: Push changes to a remote repository.Syntax: git push -u origin [branch]
git pull origin <branch>: Pull changes from a remote repository.Syntax: git pull origin [branch]

Container Management:
docker build -t <image-name>: Build a Docker image. Syntax: docker build -t [image-name]
docker run -p <host-port>: <container-port> <image>: Run a Docker container. Syntax: docker run -p [host-port]:[container-port] [image]
docker ps: List running containers.Syntax: docker ps
docker stop <container-id>: Stop a running container. Syntax: docker stop [container-id]

Image and Registry:
docker images: List Docker images.Syntax: docker images
docker rmi <image-id>: Remove a Docker image.Syntax: docker rmi [image-id]
docker push <image>: Push an image to a Docker registry. Syntax: docker push [image]