Understanding package manager and systemctl
#90 Days of DevOps Challenge - Day 7
Table of contents
- What is a package manager in Linux?
- What is a package?
- Different kinds of package managers
- Install docker in your system from your terminal using package managers
- Install jenkins in your system from your terminal using package managers
- Systemctl and Systemd
- Check the status of docker service in your system
- Stop the service jenkins and post before and after screenshots
- Systemctl vs Service
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 package manager, you must understand what a package is.
What is a package?
In Linux a package is a compressed software archive file that contains all the files that comes with a software application delivers any kind of functionality, this can be any kind of command line utility,GUI application or a software library.
A package may consist of a binary executable, configuration file and other software dependencies. Common types of Linux packages include .deb, .rpm, and .tgz. Linux packages don't usually contain the dependencies necessary to install them, therefore Linux distributions use package managers to automatically read dependencies files and download the packages needed before proceeding with the installation.
The package usually includes a manifest of dependencies that must be satisfied for a software application to execute as expected on any give Linux computer.
Common Package Managers in Linux include:
dpkg (Debian Package Manager)
APT (Advanced Package Tool)
rpm (RedHat Package Manager)
yum (Yellowdog Update Modified)
dnf (Dandified Yum)
Different kinds of package managers
Package Managers differ based on packaging system but 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.
Install docker in your system from your terminal using package managers
Step 1:- Update your system packages by running the following command
sudo apt-get update
sudo apt-get upgrade -y
Step 2:- Need to Install Docker
sudo apt-get install docker.io -y
Step3:- To check the version ned to tun below command
docker --version
or
docker -v
Step 4:- To check the Docker service status
systemctl status docker
Step 5:- If the docker service not yet started then need to run below command to start docker service
systemctl start docker
Step 6:- Verify that Docker is running correctly by running the below command
sudo docker run hello-world
Install jenkins in your system from your terminal using package managers
Step 1:- Update your system packages by running the following command
sudo apt-get update
sudo apt-get upgrade -y
Step 2:- Need to install java by following command
sudo apt-get install openjdk-11-jdk -y
Step 3:- To check the java version
java --version
Step 4:- Then run the below command to install jenkins
curl -fsSL https://pkg.jenkins.io/debian/jenkins.io-2023.key | sudo tee \
/usr/share/keyrings/jenkins-keyring.asc > /dev/null
echo deb [signed-by=/usr/share/keyrings/jenkins-keyring.asc] \
https://pkg.jenkins.io/debian binary/ | sudo tee \
/etc/apt/sources.list.d/jenkins.list > /dev/null
sudo apt-get update
sudo apt-get install jenkins -y
Step 5:- You can enable the Jenkins service to start by following command
sudo systemctl enable jenkins
Step 6:- You can start and stop the Jenkins service with the command:
sudo systemctl start jenkins
sudo systemctl stop jenkins
Step 7:- Check the status of the Jenkins service using the command:
sudo systemctl status jenkins
Step 8:- To unlock the unlock Jenkins need to run below commands
sudo cat /var/lib/jenkins/secrets/initialAdminPassword
Systemctl and Systemd
Systemd is a system and service manager for Linux operating systems, which provides a range of features such as service management, process tracking, and logging.
One of the key components of systemd is the systemctl command-line tool, which is used to control and manage system services. systemctl allows users to start, stop, restart, enable, disable, and check the status of services.
Check the status of docker service in your system
systemctl status docker
Stop the service jenkins and post before and after screenshots
Before stopping service :-
After stopping service:-
Systemctl vs Service
| systemctl | service |
| The systemctl command is a utility which is responsible for examining and controlling the systemd system and service manager. It is a collection of system management libraries, utilities and daemons which function as a successor to the System V init daemon. The new systemctl commands have proven quite useful in managing a servers services. It provides detailed information about specific systemd services, and others that have server-wide utilization. | A variety of services run continuously on a Linux background, such as network and system services. Services running on Linux are also known as daemons, which refers to a group of processes working on the back-end. Services can be managed and listed through different methods and tools. The Systemd is a software suite of tools with the ability to manage Linux systems adopted by Linux distribution as a drop-in replacement of the init process. All system tasks can be controlled through Systemd. The process can be started or ended using this tool, and all enabled and disabled services information can also be listed with Systemd. |
Command:- sudo systemctl start apache2 | Command:- sudo service apache2 start |
Thank you for reading!! I hope you find this article helpful!!
if any query or if any correction to be done in this blog please let me know.
Happy Learning!!
Saikat Mukherjee