Day 7 Task: Understanding package manager and systemctl

What is a package manager in Linux?

A package manager is a software tool that allows users to install, remove, upgrade, configure and manage software packages on an operating system. It automates the installation process, upgrading process, configuration process, and removal process of the computer programs for an operating system of the computer efficiently. A package manager works with packages, data within archive files, and software distributions.

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.

APT

(Advanced Package Tool) is a package manager used in Linux-based operating systems such as Debian, Ubuntu, and their derivatives? It is a command-line tool that simplifies the installation, removal, and updating of software packages in the system.

To update the package list from repositories.	Sudo apt update
To upgrade all installed packages to the latest version	Sudo apt upgrade
To install any package	Sudo apt install <package_name>
To remove any package	Sudo apt remove <package_name>
To search for a package that contains the keyword	Sudo apt search <keyword>
To Show package information	Sudo apt show <package_name

YUM:

(Yellowdog Updater, Modified) YUM is the default package manager for Red Hat-based distributions like CentOS and Fedora.

To update the package list from repositories.	Sudo yum update
To upgrade any installed packages to the latest version	Sudo yum upgrade
To install any package	Sudo yum install <package_name>
To remove any package	Sudo yum remove <package_name>
To search for a package that contains the keyword	Sudo yum search <keyword>
To Show package information	Sudo yum info <package_name>

Pacman :-

Pacman is the default package manager for Arch Linux and its derivatives. It is a command-line tool that allows you to search, install, update, and remove packages.

To update the package list from repositories.	Sudo pacman -syu
To install any package	sudo pacman -S package_name
To remove any package	sudo pacman -R package_name
To search for a package that contains the keyword	sudo pacman -Ss keyword
To Show package information	sudo pacman -Si package_name

Zypper :-

Zypper is the default package manager for SUSE Linux and openSUSE distributions.

To update the package list from repositories.	sudo zypper refresh
To upgrade any installed packages to the latest version	sudo zypper update
To install any package	sudo zypper install package_name
To remove any package	sudo zypper remove package_name
To search for a package that contains the keyword	sudo zypper search keyword
To Show package information	sudo zypper info package_name

systemd is a system and service manager that is used to start, stop, and manage services and daemons in the background.

To start a service	sudo systemctl start <service_name>
To stop any service	sudo systemctl stop <service_name>
To restart any service	sudo systemctl restart <service_name>
To enable a service to start automatically at boot time.	sudo systemctl enable <service_name>
To disable service to start automatically at boot time.	sudo systemctl disable <service_name>
To show the status of a service including whether it is running, stopped, or failed.	sudo systemctl status <service_name>
To reload any service	sudo systemctl reload <service_name>
To list all installed services in the system, along with their status and whether they are enabled or disabled.	systemctl list-unit-files --type=service
To list all available services on the system and their status.	service --status-all

You have to install docker and Jenkins in your system from your terminal using package managers.

install docker
sudo apt-get update #Update the package manager's cache
sudo apt-get install apt-transport-https ca-certificates curl gnupg lsb-release # Install the necessary dependencies
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg #Add the Docker GPG key to the system
echo "deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null #Add the Docker repository to the system
sudo apt-get update #Update the package manager's cache again
sudo apt-get install docker-ce docker-ce-cli containerd.io #Install Docker
sudo docker run hello-world #Verify that Docker is installed correctly by running the hello-world image

cat /etc/apt/sources.list #To check docker downloaded files

cat /etc/apt/sources.list | grep -G "#" #To check files

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Install Jenkins:

sudo apt-get update #Update the package manager's cache

sudo apt-get install -y openjdk-11-jdk #Install Java

wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key | sudo apt-key add - #Add the Jenkins repository key to the system

sudo sh -c 'echo deb https://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list' #Add the Jenkins repository to the system

sudo apt-get update #Update the package manager's cache again

sudo apt-get install jenkins #Install Jenkins

sudo systemctl start jenkins #Start the Jenkins service

sudo systemctl status jenkins #Check the status of the Jenkins service

Open a web browser and navigate to http://localhost:8080 to access the Jenkins web interface.

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check the status of the docker service in your system (make sure you completed the above tasks, else docker won't be installed)

stop the service Jenkins and post before and after screenshots

read about the commands systemctl vs service

eg. systemctl status docker vs service docker status

systemctl status docker provides more detailed information and is the preferred command on modern Linux systems that use systemd. However, service docker status can still be used on older Linux systems that use init.d scripts.

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Will appreciate your feedback :) #90daysofdevops

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Happy learning!-

Day 7 Task: Understanding package manager and systemctl

Table of contents

What is a package manager in Linux?

What is a package?

Different kinds of package managers

You have to install docker and Jenkins in your system from your terminal using package managers.

install docker

Install Jenkins:

check the status of the docker service in your system (make sure you completed the above tasks, else docker won't be installed)

stop the service Jenkins and post before and after screenshots

read about the commands systemctl vs service