Package Manager and Systemctl Basics

What is a Package Manager in Linux?

In simpler words, a package manager is a tool that allows users to install, remove, upgrade, configure, and manage software packages on an operating system. The package manager can be a graphical application like a software center or a command-line tool like apt-get or pacman.

You’ll often find me using the term ‘package’ in tutorials and articles. To understand a package manager, you must understand what a package is.

What is a Package?

A package is usually referred to as an application, but it could be a GUI application, command-line tool, or a software library (required by other software programs). A package is essentially an archive file containing the binary executable, configuration file, and sometimes information about the dependencies.

Different Kinds of Package Managers

Package managers differ based on the packaging system, but the same packaging system may have more than one package manager.

For example, RPM has Yum and DNF package managers. For DEB, you have apt-get, aptitude command-line-based package managers.

Tasks

Install Docker and Jenkins:
- Install Docker and Jenkins on your system from your terminal using package managers.
- Docker installation proof :
- Jenkins installation proof :
Write a Blog or Article:
- Write a small blog or article on how to install these tools using package managers on Ubuntu and CentOS.
- Checkout blog here: Docker and Jenkins Installation

Systemctl and Systemd

Systemctl is used to examine and control the state of the “systemd” system and service manager. Systemd is a system and service manager for Unix-like operating systems (most distributions, but not all).

Tasks

Check Docker Service Status:
- Check the status of the Docker service on your system (ensure you have completed the installation tasks above).

Answer

Manage Jenkins Service:
- Stop the Jenkins service and post before and after screenshots.
- Before stopping:
- After stopping:
Read About Systemctl vs. Service:
- Read about the differences between the systemctl and service commands.
- Example: systemctl status docker vs. service docker status.

Answer

For detail understanding of Systemctl and Service, read this blog: Understanding the Differences Between Systemctl and Service Commands in Linux

Additional Tasks

Automate Service Management:

Write a script to automate the starting and stopping of Docker and Jenkins services.
Stopped both Docker and Jenkins:

stop_services.sh:

  #!/bin/bash

  <<Info
  Author : Amitabh Soni
  date : 30/11/24
  description : This script is used to automate the stopping of Docker and Jenkins services.
  Info

  # Stopping Docker service
  sudo systemctl stop docker

  # Stopping Jenkins service
  sudo systemctl stop jenkins

  # Checking if the previous commands ran successfully
  if [[ $? -eq 0 ]]; then
     echo "Docker and Jenkins services have been stopped successfully."
  else
     echo "An error occurred while stopping Docker and Jenkins services."
  fi

start_services.sh:

  #!/bin/bash

  <<Info
  Author : Amitabh Soni
  date : 30/11/24
  description : This script is used to automate the starting of Docker and Jenkins services.
  Info

  # Starting Docker service
  sudo systemctl start docker

  # Starting Jenkins service
  sudo systemctl start jenkins

  # Checking if the previous commands ran successfully
  if [[ $? -eq 0 ]]; then
      echo "Docker and Jenkins services have been started successfully."
  else
      echo "An error occurred while starting Docker and Jenkins services."
  fi