Deboostrap a debian system

Install debian without an iso.

introduction

Normally to install a linux distribution, you would download an iso, burn it to a usb with something like rufus or etcher, and then boot into it. But this can be timely and hard to automate, an experienced user may prefer to create a system from their already existing distribution.

create partition

Open gparted, create your ext4 root partition, if you have a separate media partition and dont plan to use steam games, then <30GB should be enougth. See dual booting linux for parition schemes.

get id of new parition
```
lsblk
```
if your partition software hasn’t/can’t write a ext4 filesystem
```
  mkfs.ext4 /dev/[parition_id]
```

create a mountpoint and mount

mkdir /mnt/deb
sudo mount /dev/[parition_id] /mnt/deb

build system

This script will bootstrap a minimal debian or ubuntu system. Install

sudo apt install debootstrap

example options

variant, choose a minimal environment just for chroot or a full system
flavor choose a flavour/suite of debian, sid=unstable, bullseye=testing, buster=stable

stable has old packages but is good for servers, otherwise testing gives more up to date packages
build dir: target dir to create the system, this should be the mounted partition
debian mirror: debian mirror to use to download the packages from, choose one close to your country

sudo debootstrap 
--variant=[minbase | buildd] \
[flavor] \
[build_dir] \
[debian_mirror]

sudo debootstrap \
--variant=buildd \
bullseye \
/mnt/deb \
http://ftp.uk.debian.org/debian

config

setup fstab

get uuid of mounted parition

sudo blkid | grep -w UUID=

copy your original fstab, and replace root uuid with uuid of mounted partition

sudo cp /etc/fstab /mnt/etc/fstab

chroot

Here the root is temporary changed to the debootstraped system. Allowing for us to run commands within it. Additional mounts are needed to get some programs within the chroot to work.

mount -t proc proc /mnt/deb/proc
mount -o bind /dev /mnt/deb/dev
mount -o bind /sys /mnt/deb/sys
chroot /mnt/deb

timezone

If not using a server, you will need to set your local timezone.

find your region in /usr/share/zoneinfo/[Region]/[City] and symlink
```
  ln -sf /usr/share/zoneinfo/Europe/Berlin /etc/localtime
```

locale

If not using a server, you should configure and generate locales.

you can config locale from an interactive ncurses interface
```
dpkg-reconfigure locales
```

or you can do it manually

  vi /etc/locale.gen 
      #uncomment your locale, EG for germany
      de_DE.UTF-8 UTF-8
      de_DE ISO-8859-1
      de_DE@euro ISO-8859-15
  locale-gen
  vi /etc/locale.conf 
      LANG=de_DE.UTF-8

if you have a non-standard keyboard you may need to configure it
```
  dpkg-reconfigure keyboard-configuration
```

config network

echo -e `hostname` >> /etc/hostname
echo -e \ "127.0.0.1\tlocalhost\n::1\tlocalhost\n127.0.1.1\t`hostname`.localdomain `hostname`" >> /etc/hosts

Rather than manually configure network interfaces, its much easier just to use network-manager.

apt install network-manager

users

set the root password
```
  passwd
```

create a user and add them to the sudo group

  useradd username
  usermod -aG sudo username

install and config bootloader

Grub is the most widely used bootloader and will likely work with little config.

install, os-prober allows grub to search for other operating systems
```
sudo apt install grub os-prober
```
check if system is efi or mbr
- unless your computers quite old, it likely uses efi, /sys/firmware/efi only exists on efi systems
```
ls /sys/firmware/efi
```

if efi

make sure your efi partition is mounted

install

  sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=debian-grub

usefull tool to manage efi partition in the future
```
  sudo apt install efibootmgr
```

if mbr, where sdX is your disk

  sudo grub-install --target=i386-pc /dev/sdX

generate config, grub will also detect any other operating systems
```
sudo grub-mkconfig -o /boot/grub/grub.cfg
```

install kernel

search for a kernel
```
  apt-cache search linux-image
```
EG, the current default kernel for the amd64 architecture
```
  apt-get install linux-image-amd64
```

install any needed packages

install programs you want staright after reboot

apt-get install curl wget vim tmux

clean up chroot

exit
unmount -R /mnt 
reboot

Deboostrap a debian system