# Ubuntu

## OS Installation

Download and boot the [last Ubuntu release](https://releases.ubuntu.com/21.04/ubuntu-21.04-desktop-amd64.iso).

Follow the steps :

![img1](img/ubuntu-installation/1.png)
![img2](img/ubuntu-installation/2.png)
![img3](img/ubuntu-installation/3.png)

The partitioning is :

1. 256 MB : EFI partition
2. 20 GB : system partition

![img4](img/ubuntu-installation/4.png)
![img5](img/ubuntu-installation/5.png)
![img6](img/ubuntu-installation/6.png)

Remove the installation disk and then reboot.

Skip the welcoming window.

Don't install updates if Ubuntu asks to. The scripts will.

## Admin access

This is optional but you can add your public SSH key to access the administrator account later:

```shell
sudo mkdir /root/.ssh
echo 'ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAICeJ9WuncQJG5X51m3M0goX9fohnz9LqlL/AT3OMYBX1' | sudo tee /root/.ssh/authorized_keys
sudo chmod 400 !$
```

## OS configuration

Run a terminal and type these commands :

```shell
unset HISTFILE
sudo apt -y install git
git clone https://github.com/01-edu/public.git
public/sh/debian/ubuntu/setup.sh
```

The script will ask for student user password (which will be deleted after) and then after a long configuration process it will restart the computer.

The system is now read-only, every data is written to a temporary partition.

The session is password-less.

To gain a superuser terminal, use SSH :

```console
user@remote:~$ ssh -p521 root@IP_ADDRESS
```

To gain access with read/write access to the filesystem, use this command :

```console
root@ubuntu:~# overlayroot-chroot
INFO: Chrooting into [/media/root-ro]
root@ubuntu:/#
```