Terminal Commands Reference

A comprehensive reference of all terminal commands used across your DevOps labs.

JonC 2026-02-24

Git Commands

Command Explanation
git init Initializes a new Git repository in the current directory, creating a hidden .git folder to track changes.
git add . Stages all new and modified files in the current directory for the next commit.
git add README.md Stages a specific file (README.md) for the next commit.
git commit -m "message" Saves a snapshot of all staged changes with a descriptive message.
git status Shows the current branch, staged changes, unstaged changes, and untracked files.
git push origin main Uploads commits from your local main branch to the remote repository on GitHub.
git push origin feature-branch Uploads a specific branch to the remote repository.
git push Uploads commits to the remote repository for the currently tracked branch.
git pull origin main Downloads and merges changes from the remote main branch into your current local branch.
git pull Downloads and merges changes from the remote for the currently tracked branch.
git clone https://github.com/username/repo.git Downloads a full copy of a remote repository to your local machine, including all history.
git clone git@github.com:username/repo.git Clones a repository using SSH authentication instead of HTTPS.
git remote add origin https://github.com/username/repo.git Links your local repository to a remote GitHub repository so you can push and pull.
git branch feature-branch Creates a new branch called feature-branch without switching to it.
git checkout feature-branch Switches to an existing branch named feature-branch.
git checkout master Switches back to the master (or main) branch.
git switch feature-branch Modern alternative to git checkout for switching branches.
git merge feature-branch Merges the specified branch into the currently active branch.
git log Displays the commit history for the current branch.
ssh-keygen -t rsa -b 4096 -C your_email@example.com Generates a new RSA SSH key pair (public and private) used for authenticating with GitHub or other servers.
eval "$(ssh-agent -s)" Starts the SSH authentication agent in the background so it can manage your keys.
ssh-add ~/.ssh/id_rsa Adds your private SSH key to the running SSH agent so it can be used for authentication.
cat ~/.ssh/id_rsa.pub Prints the contents of your public SSH key to the terminal — copy this to add to GitHub.
ssh -T git@github.com Tests whether your SSH key is correctly authenticated with GitHub.
git config --global user.name "Your Name" Sets your name globally in Git, which appears on all commits you make.
git config --global user.email "you@email.com" Sets your email globally in Git, which must match your GitHub account for contributions to be attributed correctly.

Docker Commands

Command Explanation
docker pull mysql:latest Downloads the latest MySQL image from DockerHub to your local machine without running it.
docker pull mysql:8.0 Downloads a specific version (8.0) of the MySQL image from DockerHub.
docker run --name mysql-server -e MYSQL_ROOT_PASSWORD=student99 -d mysql:latest Creates and starts a MySQL container named mysql-server, running in the background (-d) with the root password set via an environment variable (-e).
docker run --name mysql-server -e MYSQL_ROOT_PASSWORD=student99 -v mysql-data:/var/lib/mysql -d mysql:latest Same as above, but also maps the mysql-data volume to persist database files across container restarts or deletions.
docker run -d -p 8080:80 --name nginx-server -v nginx-data:/usr/share/nginx/html nginx Runs an nginx container in the background, maps host port 8080 to container port 80, names it nginx-server, and mounts a volume for the web files.
docker ps Lists all currently running containers, showing their IDs, images, status, and port mappings.
docker ps -a Lists all containers, including those that are stopped.
docker stop mysql-server Gracefully stops a running container named mysql-server.
docker rm mysql-server Removes a stopped container named mysql-server. The container must be stopped first.
docker exec -it mysql-server mysql -uroot -p Opens an interactive MySQL session inside the running mysql-server container, logging in as root and prompting for a password.
docker exec -it nginx-server bash Opens an interactive bash shell inside the running nginx-server container.
docker exec -it nginx-server sh Opens an interactive sh shell — used for containers that do not include bash (common in lightweight images).
docker volume create mysql-data Creates a named Docker volume called mysql-data for persisting data outside of containers.
docker volume rm nginx-data Deletes the named volume nginx-data. The volume must not be in use by any container.
docker container inspect mysql-server Displays detailed configuration and networking information for the mysql-server container, including its IP address.
docker compose up -d Reads the docker-compose.yml file in the current directory and starts all defined services in the background.
docker compose down Stops and removes all containers, networks, and (by default) volumes defined in the docker-compose.yml file.

Docker Compose File Structure

The following is a reference template. Replace values in < > brackets with your own.

services:
  <service-name>:
    image: <image-name:version>
    container_name: <container-name>
    ports:
      - "<host-port>:<container-port>"
    volumes:
      - <volume-or-path>:<container-path>
    environment:
      - VARIABLE=value
    networks:
      - <network-name>
    restart: unless-stopped
    depends_on:
      - <other-service-name>

networks:
  <network-name>:
    driver: bridge

volumes:
  <volume-name>:
    driver: local

SQL Commands (Inside MySQL Container)

Command Explanation
show databases; Lists all databases on the connected MySQL server.
use mysql; Switches the active database to the one named mysql.
show tables; Lists all tables in the currently selected database.
select * from tables_priv; Returns all rows from the tables_priv table in the current database.
create database wordpress; Creates a new database named wordpress.
exit; Closes the MySQL connection and returns to the container shell.

Linux File System & Navigation

Command Explanation
pwd Prints the full path of the current working directory.
ls Lists files and directories in the current directory.
ls -la Lists all files (including hidden) with detailed info: permissions, owner, size, and modification date.
cd /etc Changes the current directory to /etc (absolute path).
cd ~ Changes to the current user's home directory regardless of where you are in the filesystem.
cd .. Moves up one level to the parent directory.
cd lab03 Changes to a subdirectory called lab03 within the current directory (relative path).
mkdir devops_practice Creates a new directory named devops_practice in the current location.
mkdir -p newfolder/subfolder Creates both the parent and child directories at once, without error if they already exist.
touch filename.txt Creates a new empty file named filename.txt without opening it.
cp file1 file2 Copies the contents of file1 into a new file named file2.
cp folderA/file* folderB/ Copies all files starting with "file" from folderA into folderB using a wildcard.
cp -r A/SubFolder* C Recursively copies all folders matching the pattern from A into C.
mv file2 fileB Renames file2 to fileB (move within the same directory acts as a rename).
rm file1 Permanently deletes file1 with no confirmation prompt.
rm -d folderA Removes an empty directory named folderA.
rm -rf folderB Forcefully and recursively deletes folderB and all its contents without any prompts. Use with caution.
cat /etc/passwd Prints the contents of /etc/passwd to the terminal — useful for viewing user account info.
tree Displays the directory structure in a visual tree format. Must be installed first.
vi newfile.txt Opens newfile.txt in the vi text editor. Press i to insert, ESC to exit insert mode, :wq to save and quit.
vim index.html Opens index.html in the improved vi editor (vim). Same key commands as vi.

Linux User & Permission Management

Command Explanation
sudo useradd devops_user -c "DevOps User" Creates a new system user named devops_user with the full name "DevOps User" stored in the account info.
sudo passwd devops_user Prompts you to set or change the password for devops_user.
sudo groupadd devops Creates a new group named devops.
sudo usermod devops_user -aG devops Appends (-a) devops_user to the devops group (-G) without removing them from other groups.
sudo chmod 740 A Sets folder A permissions: owner has read/write/execute (7), group has read only (4), others have no access (0).
sudo chmod u+rx devops_practice Adds read and execute permissions for the file owner without changing group or other permissions.
sudo chmod g=rx foldername Sets the group permissions to read and execute only, leaving user and other permissions unchanged.
sudo chown devops_user devops_practice Changes the owner of the devops_practice directory to devops_user.
sudo chgrp devops devops_practice Changes the group ownership of devops_practice to the devops group.
ls -la Shows permissions, ownership, size, and modification date for all files including hidden ones.

Permission Reference Chart:

Octal Binary Meaning
7 rwx Read, Write, Execute
6 rw- Read, Write
5 r-x Read, Execute
4 r-- Read only
0 --- No permissions

Example: chmod 754 = owner rwx (7), group r-x (5), others r-- (4)

Linux Networking

Command Explanation
ip addr Displays all network interfaces and their assigned IP addresses.
ifconfig Older command for displaying network interface configuration. May need to be installed.
ping google.com Sends ICMP packets to google.com to test network connectivity. Press CTRL+C to stop.
ping 172.17.0.2 Pings a specific IP address — useful for testing container-to-container connectivity.
wget https://example.com/file.tar.gz Downloads a file from the given URL directly to the current directory.
curl https://example.com/file Transfers data from a URL. More flexible than wget — can send and receive data.
netstat Displays active network connections, routing tables, and interface statistics.
ss Modern replacement for netstat — shows socket statistics and active connections.

Linux Package Management (Red Hat / RHEL / Amazon Linux)

Command Explanation
sudo dnf update Updates the local package index with the latest available package versions.
sudo dnf upgrade Installs all available upgrades to currently installed packages.
sudo dnf -y update Updates the package index and automatically answers yes (-y) to all prompts.
sudo dnf install nginx Installs the nginx web server package.
sudo dnf -y install tree Installs the tree utility, automatically confirming the install.
sudo dnf install -y stress Installs the stress tool for generating CPU/memory load.
sudo yum install httpd Installs the Apache HTTP server using yum (used on older Amazon Linux versions).
sudo yum install -y epel-release Installs the EPEL repository, expanding the available package list.
sudo amazon-linux-extras enable epel Enables the EPEL extra repository on Amazon Linux instances.
apt update Updates the package index on Debian/Ubuntu-based systems.
apt install -y vim Installs vim on Debian/Ubuntu-based systems, auto-confirming the install.

Linux Service Management (systemctl)

Command Explanation
sudo systemctl enable nginx Configures nginx to start automatically on system boot.
sudo systemctl start nginx Starts the nginx service immediately.
sudo systemctl status nginx Displays the current running status of the nginx service, including recent log output.
sudo systemctl start httpd Starts the Apache HTTP server (httpd) service.
sudo service httpd start Older-style command to start the httpd service — equivalent to systemctl start on supported systems.

Linux Monitoring & System Info

Command Explanation
uname -a Prints detailed system information: kernel name, version, hostname, architecture, and OS.
df -h Shows disk space usage for all mounted filesystems in human-readable format (KB, MB, GB).
ps Lists processes running in the current shell session.
top Displays a real-time, continuously updating list of running processes and resource usage.
sudo stress --cpu 1 --timeout 120 Runs a CPU stress test using 1 core for 120 seconds — used to generate load and test CloudWatch alarms.
sudo poweroff Shuts down the Linux system immediately.

SSH Commands

Command Explanation
ssh -l ec2-user -i ~/.ssh/Western-Student ec2-XX-XX.compute-1.amazonaws.com Connects via SSH to an AWS EC2 instance using a specific username (-l) and private key file (-i).
ssh -o StrictHostKeyChecking=no -i private_key.pem ec2-user@hostname Connects via SSH while skipping the host key verification prompt — used in automated scripts.

AWS CLI / Workflow Commands

Command Explanation
git push In a CI/CD context, pushing code to the main branch triggers the GitHub Actions workflow automatically.
aws s3 sync . s3://bucket-name --exclude ".git/*" Syncs local files to an S3 bucket, excluding the .git directory — used in deployment pipelines.
tar -xzvf wordpress-6.7.1.tar.gz Extracts a compressed .tar.gz archive, showing each file as it is extracted (-v for verbose).
npm test Runs the test script defined in package.json — in a CI/CD pipeline this must pass before deployment.
chmod 600 private_key.pem Sets the private key file to owner-read-only permissions, required by SSH before using the key.

Node.js / npm Commands

Command Explanation
npm test Executes the test script defined in the scripts section of package.json.
node test.js Runs the test.js file directly using Node.js.