90DaysOfDevops

Day 7 Task: Understanding Package Manager and Systemctl

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Manav Raut
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4 min read

Table of contents

What is a Package Manager in Linux? 🐧

A package manager is a tool that simplifies installing, updating, and removing software on Linux. Instead of manually downloading and installing software, you can use a package manager to automatically manage everything, including dependencies (other software the program might need to run). 🔧

There are two main types of package managers: Graphical (with a user interface) 🖥️ and Command-Line (operated using terminal commands) 💻.

What is a Package? 📦

A package is a compressed archive that contains:

  • The program's binary files (the files you run). ⚙️

  • Configuration files. 🛠️

  • Information about dependencies (other packages required for the software to run). 🔗

Examples of Package Managers in Linux 🐧

1. apt (Advanced Package Tool)

Used in Debian-based systems like Ubuntu, apt handles .deb packages.

  • Install a package: 📥
  •   sudo apt install package_name

    Example: 🌟

      sudo apt install nginx

    This command installs the NGINX web server, downloading and configuring all necessary components and dependencies automatically. 🌐✨

  • Update all packages: 🔄✨

      sudo apt update && sudo apt upgrade

  • Remove a package: 🗑️

      sudo apt remove package_name

    Example:

      sudo apt remove nginx

2. yum (Yellowdog Updater Modified) / dnf 🐾

Used in RPM-based systems like Red Hat, CentOS, or Fedora, yum and dnf handle .rpm packages. 📦

  • Install a package: 📥
  •   sudo yum install package_name  # For older versions
  sudo dnf install package_name  # For newer versions of Fedora

    Example:

      sudo dnf install httpd

    • This installs the Apache web server. 🌐

    • Update packages: 🔄✨

  •   sudo dnf update

  • Remove a package: 🗑️

      sudo dnf remove package_name

3. pacman 🎮

Used in Arch-based systems like Arch Linux and Manjaro, pacman handles .pkg.tar.xz packages. 🐧📦

  • Install a package: 📦✨

      sudo pacman -S package_name

    Example:

      sudo pacman -S firefox

  • Update all packages: 🔄✨

      sudo pacman -Syu

  • Remove a package: 🗑️

      sudo pacman -R package_name

Why Use a Package Manager? 🤔

  • Simplifies installation: You don’t have to manually download files and handle dependencies. 📦

  • Automatic updates: Package managers keep your software up-to-date. 🔄✨

  • Easier uninstallation: They handle removing software and cleaning up unnecessary files. 🧹

Task 1: Check Docker Service Status 🐳

To check the status of the Docker service on your system, use the following command: 🖥️

sudo systemctl status docker

This will provide information about whether the Docker daemon is running, its status, and any relevant logs. 📊🔍

Task 2: Manage Jenkins Service ⚙️

To stop the Jenkins service:

  1. Check the status of the Jenkins service before stopping it: 🔍

  2.   sudo systemctl status jenkins

  3. Stop the Jenkins service: ⏹️

     sudo systemctl stop jenkins

  4. Check the status of the Jenkins service after stopping it: 🔍

     sudo systemctl status jenkins

Make sure to capture screenshots both before and after stopping the Jenkins service to compare the changes. 📸🔄

Task 3: Read About systemctl vs. service 📚

  • systemctl: It’s a command used to manage services on systems that use systemd. systemctl can start, stop, restart services, and provide more control over services. ⚙️

    Example:

  •     sudo systemctl status docker

    • This will show the active status of the Docker service, with more detailed logs from systemd. 📄

    • service: This command is used to manage services on systems that don’t use systemd but instead use init or upstart. On systemd-based systems, service is often backward-compatible but provides less information than systemctl. 🔄

      Example: 📝

    sudo service docker status

This will provide basic service status information but with fewer details. 📋

Task 4: Automate Service Management 🤖

You can write a shell script to automate starting and stopping Docker and Jenkins services. 🚀

#!/bin/bash

# Check command-line arguments
if [ "$1" == "start" ]; then
    echo "Starting Docker and Jenkins services..."
    sudo systemctl start docker
    sudo systemctl start jenkins
elif [ "$1" == "stop" ]; then
    echo "Stopping Docker and Jenkins services..."
    sudo systemctl stop docker
    sudo systemctl stop jenkins
else
    echo "Usage: $0 {start|stop}"
    exit 1
fi

# Check service status
echo "Docker status:"
sudo systemctl status docker | grep "Active"

echo "Jenkins status:"
sudo systemctl status jenkins | grep "Active"

Save this as manage_services.sh and run it as follows: 💾▶️

chmod +x manage_services.sh
./manage_services.sh start    # To start services
./manage_services.sh stop     # To stop services

Task 5: Enable and Disable Services ⚙️

  • To enable Docker to start on boot: 🚀
sudo systemctl enable docker

  • To disable Jenkins from starting on boot:

      sudo systemctl disable jenkins

Task 6: Analyze Logs 🔍

To analyze logs using journalctl, use the following commands:

  1. View Docker service logs: 🐳📜
sudo journalctl -u docker

  1. View Jenkins service logs: 📜🛠️

     sudo journalctl -u jenkins

These commands will show detailed logs of the Docker and Jenkins services, including when they were started, stopped, and any errors that occurred. 📊🛠️ Post your findings based on the logs generated by journalctl. 📈🔍

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