Command Reference

Docker and Docker Compose Guide Introduction Docker is a platform for developing, shipping, and running applications inside containers. Docker Compose is a tool for defining and running multi-container Docker applications using YAML files. This guide covers essential Docker and Docker Compose commands, with practical examples, to help you manage containers effectively. What is Docker? Docker allows you to package applications with their dependencies into containers, ensuring consistency across different environments. Containers are lightweight, portable, and run independently of the host system. ...

Git and Gitflow Guide Introduction Git is a distributed version control system that enables multiple developers to collaborate on projects efficiently. Gitflow is a popular branching model that organizes Git branches for streamlined development and release management. This guide covers essential Git commands, introduces the Gitflow workflow, and provides practical examples for managing code repositories. What is Git? Git tracks changes to files, allowing multiple users to work on the same project without conflicts. It supports branching, merging, and version history, making it ideal for software development and collaborative projects. ...

Linux Sysadmin Commands Guide Introduction As a Linux system administrator, mastering essential commands is crucial for managing servers, monitoring systems, and troubleshooting issues. This guide covers fundamental Linux commands for system administration, focusing on user management, process control, network diagnostics, and system monitoring, with practical examples. Prerequisites A Linux system (e.g., Ubuntu, CentOS, or Debian). Root or sudo privileges. Basic familiarity with the terminal. System Information Hardware and System Overview # Display system information uname -a # Show CPU details lscpu cat /proc/cpuinfo # Display memory usage free -h cat /proc/meminfo # List block devices (disks) lsblk fdisk -l # Requires sudo # Show mounted filesystems df -h System Uptime and Load # Display system uptime and load average uptime # Show load average cat /proc/loadavg # Interactive system monitoring top htop # If installed User and Group Management Managing Users # Add a new user sudo useradd -m -s /bin/bash username # Set a password for the user sudo passwd username # Modify user details sudo usermod -aG groupname username # Add user to a group sudo usermod -s /bin/zsh username # Change shell # Delete a user sudo userdel -r username # Remove user and home directory Managing Groups # Create a new group sudo groupadd groupname # Add user to a group sudo usermod -aG groupname username # List groups getent group # Delete a group sudo groupdel groupname Example: Creating a User with Specific Permissions Create a user devuser with sudo privileges: ...

QEMU Disk Image and VM Management Guide Introduction QEMU is a powerful open-source emulator and virtualizer for running virtual machines (VMs) and managing disk images on Linux systems. It supports a wide range of architectures and provides tools for creating, manipulating, and running VMs with flexible configurations. This guide covers essential QEMU commands for disk image management and VM operations, with practical examples for system administrators and developers. Prerequisites QEMU installed on a Linux system (qemu-system-x86_64 --version to verify). Root or sudo privileges for certain operations (e.g., installing QEMU or accessing KVM). Basic understanding of Linux terminal commands and virtualization concepts. Install QEMU on Ubuntu/Debian: ...

SSH Forward Tunneling Guide Introduction SSH forward tunneling (also known as local port forwarding) allows you to securely connect to a remote service through an SSH server, making it appear as if the service is running on your local machine. This is useful for accessing services on a remote server or another machine in a secure network that aren’t directly accessible. In this guide, we’ll cover the basics of SSH forward tunneling, explain how it works, and provide practical examples. ...

Ubuntu UFW Firewall Guide Introduction UFW (Uncomplicated Firewall) is a user-friendly interface for managing iptables firewall rules on Ubuntu systems. It simplifies the process of configuring firewall settings, making it accessible for beginners and efficient for advanced users. This guide covers essential UFW commands, practical examples, and tips for securing your Ubuntu server. What is UFW? UFW is a front-end for iptables, designed to make firewall configuration straightforward. It allows you to manage inbound and outbound network traffic by defining rules based on ports, protocols, and IP addresses. ...

Introduction In this tutorial, we’ll explore fundamental Bash commands that every developer should master. We’ll start with disk space analysis and expand to cover essential file operations. Disk Space Analysis Basic Command Here’s a useful command to list files by size: du -sh * | sort -h Command Breakdown du -sh *: du = disk usage -s = summary (total only for directories) -h = human-readable format (KB, MB, GB) * = all files/directories in current folder sort -h: sorts human-readable values numerically ...