What is a package?

In Linux, a package refers to a compressed file archive that contains software, along with metadata and instructions for its installation. Packages are a standardized way of distributing and installing applications, libraries, and other software components on Linux systems. Different Linux distributions use package management systems to handle the installation, removal, and updating of software packages. Two common package management systems are Advanced Package Tool (APT) used by Debian and Ubuntu, and Yellowdog Updater, Modified (YUM) used by Red Hat and its derivatives.

Key aspects of Linux packages include:

1. Format:

   • Packages are typically compressed archives, often in formats like tar, gzip, or other archive formats.

2. Metadata:

   • Each package contains metadata providing information about the software, such as version, dependencies, and maintainer details.

3. Dependencies:

   • Packages often specify dependencies, which are other software components or libraries required for the proper functioning of the installed software.

4. Installation:

   • Package management tools handle the installation process, resolving dependencies and ensuring that the software is correctly configured on the system.

5. Updates and Removal:

   • Package managers facilitate the updating of installed software to newer versions and allow for the removal of unwanted packages.

6. Repository:

   • Packages are usually stored in repositories, which are centralized locations where users can access a collection of pre-compiled and tested software packages.

Examples of package management commands:

• For Debian/Ubuntu systems (APT):

    sudo apt-get install package_name
    sudo apt-get remove package_name
    sudo apt-get update
  

• For Red Hat-based systems (YUM/DNF):

    sudo yum install package_name
    sudo yum remove package_name
    sudo yum update
  

Using packages simplifies the process of software management on Linux systems, enhancing efficiency and ensuring consistency across different installations. It also aids in maintaining system security by providing a centralized and controlled method for software deployment and updates.

What is a package manager in Linux?

A package manager in Linux is a software tool or system that automates the process of installing, updating, configuring, and removing software packages on a Linux system. It streamlines the management of software by handling dependencies, resolving conflicts, and ensuring a consistent and efficient way to install and maintain applications.

Key features of package managers in Linux:

1. Repository Management:

   • Package managers use repositories, which are centralized databases of software packages. These repositories contain pre-compiled and pre-configured software ready for installation.

2. Dependency Resolution:

   • Package managers automatically identify and install any additional software libraries or components required for a given package to function correctly. This helps prevent compatibility issues.

3. Installation and Removal:

   • Package managers handle the installation and removal of software packages. Users can easily install new software or remove existing ones without dealing with manual configurations.

4. Updates:

   • Package managers provide mechanisms for updating installed software to newer versions. This ensures that the system is up-to-date with the latest features and security patches.

5. Configuration Management:

   • Package managers often include tools for configuring software after installation. This may involve setting up default configurations or prompting the user for specific settings.

6. Conflict Resolution:

   • In cases where multiple packages have conflicting requirements or files, package managers resolve conflicts by selecting appropriate versions or managing file locations.

Common package managers in Linux include:

• Advanced Package Tool (APT):

  • Used by Debian and Ubuntu-based systems. Commands include apt-get and apt.

• Yellowdog Updater, Modified (YUM) / DNF (Dandified YUM):

  • Used by Red Hat, CentOS, and Fedora-based systems. Commands include yum (for older systems) and dnf (for newer systems).

• Pacman:

  • Used by Arch Linux. Commands include pacman.

• Zypper:

  • Used by openSUSE. Commands include zypper.

• Emerging Package System (Portage):

  • Used by Gentoo Linux. Commands include emerge.

Package managers significantly simplify the process of software management on Linux systems, making it easier for users to install, update, and maintain software packages in a consistent and controlled manner. They contribute to system stability, security, and ease of use.

What is systemctl and systemd?

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

Tasks

Task1: Install to the Docker, Start to the Docker and check the status of Docker service in your system.

Install to the Docker:

sudo apt-get install docker.io

Start the Docker:

sudo systemctl start docker

Check the Status of Docker Service:

sudo systemctl status docker

Stop the Docker Service:

sudo systemctl stop docker

Check the Status of Docker Service :

sudo systemctl status docker

Task2: Install to the Jenkins, Start to the Jenkins and check the status of Jenkins service in your system.

Install to the Jenkins:

sudo apt-get update
sudo apt-get install openjdk-8-jdk
wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key | sudo apt-key add -
sudo sh -c 'echo deb https://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'
sudo apt-get update
sudo apt-get install jenkins

Start the Jenkins:

Sudo systemctl start jenkins

Check the status of Jenkins service:

sudo systemctl status jenkins

Stop the Jenkins Service:

sudo systemctl stop jenkins

Check the status of Jenkins service:

sudo systemctl status jenkins