OS GNU/Linux

GNU and Linux are two different things that together form what people casually call “Linux.”

GNU

• A project started in 1983 by Richard Stallman.

• Its goal was to create a completely free operating system, compatible with Unix.

• GNU provides:
  • the compiler (GCC),
  • the shell (bash),
  • system utilities (ls, cp, rm, etc.),
  • libraries,
  • and the whole user-space toolset needed to run an OS.

• What GNU didn’t have back then was the kernel — the core of the system.

Linux

• Created in 1991 by Linus Torvalds.

• Linux is the kernel, the part of the operating system that talks directly to the hardware (CPU, memory, disks, etc.).

• By itself, Linux can’t do much — you can’t even type commands or compile programs without GNU tools.

GNU/Linux

• The system we actually use is GNU + Linux.
  • GNU = the user tools
  • Linux = the kernel

• Together, they make a complete operating system such as Debian, Ubuntu, Fedora, or Arch Linux.

• Stallman insists on calling it “GNU/Linux” to acknowledge the GNU project’s work.

  Most people just say “Linux” for simplicity.

When Richard Stallman started GNU in the 1980s, the goal was to build a completely free operating system, including its own kernel.

But that kernel — called Hurd — ran into major delays.

Timeline:

• 1983 – Stallman launches the GNU Project.

• 1984–1990 – The team builds all the user-space tools (GCC compiler, Bash shell, core utilities, etc.).

• 1990 – They begin work on the GNU Hurd kernel, designed to run on top of the Mach microkernel (a very modular architecture).

• 1991 – Linus Torvalds releases the Linux kernel, which is simpler, monolithic, and — crucially — it worked.

What happened next:

• GNU had everything except the kernel,

• Linux had a working kernel but no user tools.

• Combine them → you get a complete GNU/Linux system.

What about Hurd?

The GNU Hurd still exists, maintained by the Free Software Foundation, but it remains experimental and is mostly used for research.

There are niche distributions like Debian GNU/Hurd, but they’re far less stable and widely used than GNU/Linux.

Summary

The Linux kernel isn’t a copy of anything, but it didn’t appear out of nowhere either.

Linus Torvalds wrote it entirely from scratch, while taking strong inspiration from Unix — especially Minix, a small Unix-like system used for teaching.

The nuance:

• Linux contains no Unix code (no direct reuse).

• But it adopts Unix concepts and structure:
  • file hierarchy (/etc, /usr, /bin, …),
  • process and permission management,
  • the “everything is a file” philosophy,
  • and the POSIX standard interface (the Unix programming API).

The context:

• In 1991, Linus Torvalds was a student at the University of Helsinki.

• He was using Minix, a minimalist Unix-like OS created by Andrew Tanenbaum for educational purposes.

• Frustrated by its limitations, he decided to write his own kernel, more complete and efficient.

• He released it under a free software license, and the open-source community quickly joined in.

So: Linux is a free reimplementation of a Unix-like system, not a copy.

It follows Unix standards without being Unix itself.

VPS

What is a VPS

A VPS (Virtual Private Server) at OVH is a virtual server hosted in OVH’s data centers. It gives you the equivalent of a small dedicated server, but it’s virtualized — you share the physical machine with other users while keeping your own isolated environment.

In short:

• You get your own dedicated resources (CPU, RAM, storage, public IP);

• You can install anything you want (Linux, Debian, Ubuntu, Windows, etc.);

• You have root access — full control of the system;

• You can host multiple websites, apps, databases, or tools on it.

It’s a middle ground between:

• Shared hosting (cheap, but limited control),

• and a dedicated server (powerful, but more expensive).

With OVH, you can choose:

• The plan (Starter, Value, Essential, etc.) based on performance (CPU/RAM);

• The data center location (France, Germany, Canada…);

• The preinstalled operating system (Debian, Ubuntu, Plesk, Docker, etc.);

• And you can manage or reinstall your VPS remotely through the OVHcloud dashboard.

It’s commonly used for:

• Hosting websites or web applications (WordPress, Node.js, PHP, etc.),

• Running a Git server (like Gitea or GitLab CE),

• Deploying databases,

• or hosting teaching or testing environments.

OVH

We rent a VPS to OVH hosting company. OVH is a French company created by Octave Klaba in 19xx. The name of OVH is “On vous héberge”.

Connection

SSH

the usual port 22

The good practise to have more security is to change the port number. Choose one on this range 49152 and 65535.

Installation of the OS and configuration

• install Debian (made by OVH)

• update the OS

  apt is the package manager used by Debian and its derivatives (like Ubuntu).

  It’s a command-line tool that lets you install, update, remove, or search for software on your system.

  In simple terms:

  • apt retrieves programs from the official repositories configured on your machine.
  • It automatically installs all required dependencies.
  • It keeps track of installed packages so they can be updated later.

  cd /
  sudo apt update // check the updates available
  
  sudo apt list --upgradable // check the list of package to update
  sudo apt upgrade // pour upgrader l'ensemble

• Firewall
  • Check the state of the firewall

    sudo iptables -L

• Network tools / net-tools

sudo  apt-get install net-tools

netstat -a

• FTP client
  • to get files or put files on your server
  • soft : Filezilla, Cyberduck