| Class time 2 h lecture + 2 h lab |
Study at home about 3 h |
Outcomes LO 1, 2, 6 (start of 11) |
Before this Week 1 + your VM |
| 1. What you will learn 2. Two minutes to remember Week 1 3. Two videos to watch 4. What is inside a distribution 5. Two ways to release a system 6. LTS and the version numbers 7. Repositories and the package manager |
8. The desktop is not the distribution 9. The families, one by one 10. How to choose a distribution 11. Download safely: the checksum 12. Practice terminal (try it here) 13. Command card |
14. Mistakes everybody makes 15. Small dictionary + abbreviations 16. Laboratory 2 — planning 17. Check yourself 18. Learning outcomes 19. Next week and extra videos |
After this session you will be able to:
apt to search and install a package.| Kernel | The engine. One project, written since 1991, the same in every distribution. |
| Distribution | The complete car built around that engine. This week is about the car. |
| Shell / terminal | The program that reads your command, inside the window that shows the letters. |
| root and sudo | root is the administrator. You work as a normal user and put sudo before a command that changes the system. You will need this today. |
A fast tour of the distributions, then a calm explanation of how to choose one.
There are hundreds of distributions and they all use the same kernel. So what is actually different? Six things — and when you compare two distributions, you compare these six:
This single decision explains most of the difference between distributions.
| Fixed release | Rolling release | |
|---|---|---|
| New version | On a known date (Ubuntu: every 6 months, LTS every 2 years) | Never — the system is always "the current one" |
| Software age | Older, but tested for months | The newest that exists |
| Risk | Low — a server can run for years untouched | Higher — an update can change or break something |
| Good for | Servers, companies, laboratories, students | Personal machines of experienced users |
Ubuntu numbers are not random. 26.04 means the version published in the fourth month of 2026. Every two years the April version is marked LTS — Long Term Support: it receives security updates for five years instead of nine months.
.1.
Other families do the same thing with other numbers:
| Distribution | New version arrives | Security updates last |
|---|---|---|
| Ubuntu LTS | every 2 years (April) | 5 years |
| Ubuntu normal | every 6 months | 9 months |
| Debian stable | about every 2 years | about 5 years |
| Fedora | every 6 months | about 13 months |
| RHEL / Rocky / Alma | every 3 years | 10 years |
| Arch | no versions (rolling) | always the newest |
In Windows you search the web, download a .exe from some site and hope it is clean. Linux does not work like that. Every distribution has its own repositories: official servers holding thousands of checked programs. The package manager — on Ubuntu it is called apt, the Advanced Package Tool — takes what you ask for from there.
The commands are simple, and they are the same idea in every family:
| You want to… | Ubuntu / Debian | Fedora / RHEL |
|---|---|---|
| refresh the list of software | sudo apt update substitute user do · Advanced Package Tool | sudo dnf check-update |
| search for a program | apt search htop | dnf search htop |
| read the details first | apt show htop | dnf info htop |
| install it | sudo apt install htop | sudo dnf install htop |
| remove it | sudo apt remove htop | sudo dnf remove htop |
| update the whole system | sudo apt upgrade Advanced Package Tool | sudo dnf upgrade |
| see what is installed | apt list --installed Advanced Package Tool | dnf list installed |
Two habits to build now: run apt update before you install anything, and read apt show before you accept a package you do not know.
Beginners think "Ubuntu looks like this and Fedora looks like that". Wrong. What you see — the panel, the menu, the windows — is a separate program called a desktop environment, and you can put almost any of them on almost any distribution.
Our laboratory machine is Ubuntu Server: no desktop at all. That is not poverty — it is the normal choice for a server. A desktop would eat memory, add programs nobody uses, and every extra program is one more door an attacker can try.
| Name | Family | Who uses it, and why |
|---|---|---|
| Ubuntu | Debian | The most common starting point. Huge amount of help on the internet, an LTS every two years, and most cloud servers run it. Our choice for the laboratory. |
| Debian | Debian | The father of Ubuntu. Run by volunteers, extremely stable, slower to add new software. Very common on servers that must simply keep working. |
| Linux Mint | Debian | Ubuntu with a friendlier desktop. A good first system for someone coming from Windows. |
| Kali Linux | Debian | Debian with six hundred security-testing tools already installed. You will meet it later in your programme. It is a working tool for authorised tests, not a daily system for a student — and installing it does not by itself make anybody a security engineer. |
| Fedora | Red Hat | Where Red Hat tests new ideas. Newest software, short support. Popular with developers. |
| RHEL | Red Hat | The paid enterprise system: ten years of support and a company to call. Banks, telecoms and ministries buy it. Rocky Linux and AlmaLinux are free rebuilds of it. |
| openSUSE | SUSE | Strong in European industry. Known for YaST, a single tool to configure the whole system. |
| Arch | Arch | You build the system yourself, piece by piece. Excellent documentation. Teaches a lot — after you already know the basics. |
There is no "best distribution". There is only the right one for a given job. Ask three questions in this order:
You are about to download a 2.6 GB file and then give it control of a whole computer. Two things can go wrong: the download breaks in the middle, or somebody gives you a modified image with something extra inside. Both are solved by the same tool.
A checksum (or fingerprint, or hash) — here SHA-256, the Secure Hash Algorithm with a 256-bit answer — is a long number calculated from every single byte of a file. Change one byte — one — and the number changes completely. The project publishes the correct number; you calculate yours and compare.
How you do it on each system:
There is one more level, which you will study later: the file of checksums is itself signed with a GPG key (GNU Privacy Guard) belonging to the project. The checksum proves the file did not change; the signature proves the checksum itself came from Ubuntu and not from an attacker who replaced both.
Install a package and verify a download here first — then do it for real on your virtual machine.
apt and the checksum command sha256sum. Nothing here touches a real computer. Type help to begin.
help = the list of commands · commands that change the system need sudo
Add this card to the one from Week 1.
| Command | What it does |
|---|---|
| lsb_release -a Linux Standard Base, all | Shows the distribution, its version and its codename |
| cat /etc/os-release concatenate | The same information, works on every distribution |
| sudo apt update | Refreshes the list of available software (does not install anything) |
| sudo apt upgrade | Installs the newer versions of what you already have |
| apt search <word> Advanced Package Tool | Searches the repositories for a program |
| apt show <package> Advanced Package Tool | Shows the details: version, size, what it is for |
| sudo apt install <p> Advanced Package Tool | Installs a package and everything it depends on |
| sudo apt remove <p> Advanced Package Tool | Removes a package |
| apt list --installed | Lists everything installed on the machine |
| apt list --upgradable Advanced Package Tool | Lists what has a newer version waiting |
| sha256sum <file> Secure Hash Algorithm, 256 bits | Calculates the fingerprint of a file |
| dnf / zypper / pacman Dandified YUM · SUSE tool · package manager | The same work on Fedora / SUSE / Arch |
Six problems you will certainly meet, and the answer to each.
| What you see | Why | What to do |
|---|---|---|
| Permission denied · Are you root? | Installing changes the whole system, so it needs administrator rights. | Put sudo in front: sudo apt install … |
| E: Unable to locate package | Your list of available software is old, or the name is misspelled. | Run sudo apt update, then apt search the name. |
| "I ran apt update but nothing was installed" | update refreshes the list. upgrade installs. |
Remember the pair: update, then upgrade. |
A .rpm file will not install on Ubuntu |
That is the package format of the Red Hat family. | Look for the same program with apt search. It is almost always there. |
| Downloading a program from the first site Google shows | Those files are signed by nobody. This is how machines get infected. | Use the repositories first. They are the safe source. |
| Installing an image without checking its checksum | A broken or modified image can fail halfway — or work perfectly and spy on you. | Always compare the fingerprint. It takes thirty seconds. |
| Word | Meaning in one line |
|---|---|
| Package | One program wrapped in a file together with its description and its list of needs (.deb or .rpm). |
| Repository | The official server holding thousands of checked packages for your distribution. |
| Mirror | A copy of that server in another country, so the download is faster. |
| Dependency | Another package that a program needs in order to run. apt installs them for you. |
| LTS | Long Term Support — a version that keeps receiving security fixes for five years. |
| Rolling release | A system with no versions: small updates arrive continuously. |
| Codename | The nickname of a version — Ubuntu 26.04 is "resolute". Commands and files often use it. |
| ISO image | One big file containing a whole installation disk. |
| Checksum / hash | A fingerprint calculated from a file, used to prove the file did not change. |
| GPG signature | A cryptographic proof of who published a file. Packages and checksum files are signed. |
| Desktop environment | The graphical face of the system (GNOME, KDE, XFCE). A server has none. |
| Snapshot | A saved state of a virtual machine, so you can return to it after a mistake. |
The package tools and the security words are all abbreviations. Here is what each one actually says.
| Command | The name means | What that tells you |
|---|---|---|
| apt | Advanced Package Tool | The software store of the Debian family: apt update, apt search, apt install. |
| dpkg | Debian package | The low-level tool under apt. A package file ends in .deb — Debian. |
| dnf | Dandified YUM | The Red Hat family tool. YUM itself = Yellowdog Updater, Modified. |
| rpm | RPM Package Manager | The package format of the Red Hat family — a .rpm file. The name originally meant Red Hat Package Manager. |
| pacman | package manager | The Arch Linux tool. |
| zypper | not an abbreviation | The openSUSE tool — simply its name. |
| lsb_release | Linux Standard Base release | Prints the distribution, its version and its codename. |
| sha256sum | SHA-256 sum | Calculates the SHA-256 fingerprint of a file. SHA = Secure Hash Algorithm; 256 = the length of the number in bits. |
| htop | the friendlier top | top shows the processes using most of the machine; htop shows the same with colours and a tree. |
| Short name | It stands for | In one line |
|---|---|---|
| LTS | Long Term Support | A version that keeps receiving security fixes for five years instead of nine months. |
| ISO | an ISO 9660 disc image | A whole installation disc kept in one file. The standard is published by the International Organization for Standardization. |
| SHA-256 | Secure Hash Algorithm, 256 bits | The fingerprint you compare after a download. |
| GPG | GNU Privacy Guard | The tool that signs files. The signature proves who published the checksum. |
| RHEL | Red Hat Enterprise Linux | The paid enterprise system with ten years of support. |
| amd64 / x86_64 | the 64-bit PC processor family | You will see it in every package name and image name. |
| GNOME | from “GNU Network Object Model Environment” | A desktop environment. The project dropped the old expansion; today it is simply a name. |
| KDE | K Desktop Environment | A desktop environment with many settings. |
| XFCE | began as “XForms Common Environment” | A light desktop environment for older machines. |
Notice the pattern: apt, dnf, zypper and pacman are four names for the same job — take a checked, signed program from the official servers and install it with everything it needs.
Last week you installed a machine because the teacher told you to. This week you decide why. Planning before installing is what separates an engineer from a person who clicks Next.
For each situation below, write in your report: the distribution you choose, the release model, how long it is supported, and two lines of justification.
| # | The situation |
|---|---|
| A | The college needs a web server for the student portal. It must run for at least four years with as few reinstalls as possible, and one technician will look after it. |
| B | A laboratory of fifteen old computers with 2 GB of memory each, to be used for teaching programming to first-year students. |
| C | A virtual machine for a graduation project in network security testing, isolated from the college network. |
Get-FileHash on Windows, sha256sum on Linux).On the virtual machine from Week 1, run these and keep a screenshot of each:
Write one line about what htop shows you that free -h does not.
In VirtualBox, with the machine switched off, open Snapshots and take one called clean-after-week2. From now on, whenever you break something in a later laboratory, you return to this point in one click instead of reinstalling for an hour. Put a screenshot of the snapshot list in your report.
| Three situations answered with a real justification (not one word) | 3 |
| Both checksums shown, compared, and the "what if" question answered | 3 |
| The eight commands with screenshots, htop installed and running | 3 |
| Snapshot created and shown | 1 |
CSTE2103_Lab2_<your number>.pdf on IQ-LEARN before the next laboratory.sudo apt update does what? (a) installs new versions (b) refreshes the list of available software (c) upgrades the kernelsudo apt upgrade.sudo apt install nmapsudo dnf install nmap — same idea, different package manager.| Outcome | From the module description form | Covered by |
|---|---|---|
| LO 1 | Basic Linux knowledge — identify the differences between the different distributions | Sections 4–6, 8–10; questions 1, 3, 4, 7 |
| LO 2 | Installing and configuring Linux systems to meet personal or professional needs | Section 10; laboratory steps 1, 3, 4 |
| LO 6 | Software and package management — install, update and remove software | Section 7, 13; terminal missions 2–5; laboratory step 3 |
| LO 11 | Applying security principles | Sections 6, 7, 11; terminal missions 6–7; laboratory step 2 |
Examined in Quiz 1 (Week 5), the midterm (Week 8) and the final examination.
Week 3 — Navigating the file system. The tree you saw in Week 1, but this time you will live in it: moving, looking, finding, and understanding absolute and relative paths. Bring your virtual machine with the snapshot already taken.