UbuntuMini.iso setup with UEFI for REMnux

UbuntuMini.iso Install Guide:

By default the Ubuntu minimal .iso will only boot with a legacy BIOS. So im going to show you how you can get a UbuntuMini.iso on a UEFI system so we can install a minimal Ubuntu setup for REMnux. For this to happen we must build our own ISO using the Ubuntu minimal ISO, and a Ubuntu Server ISO.
Through my research on this, I came across a script on Noobient

First lets create a temp directory for our work:
$ mkdir /tmp/remnux

Next we will create a file for our script: (You can call this whatever you'd like, I personally just named it customiso.sh)
$ touch customiso.sh

Lets copy the script into the customiso file, then make it executable. You can use whatever text editor you would like. I will be using vim in this example.
$ vim customiso.sh

#!/bin/bash
set -eu
server_iso=‘ubuntu-20.04.1-legacy-server-amd64.iso’

mini_iso=‘mini.iso’

dist_dir=‘ubuntu-20.04-netinstall’
if [ ! -e ${server_iso} ]

then

wget “https://cdimage.ubuntu.com/ubuntu-legacy-server/releases/focal/release/${server_iso}”

fi
if [ ! -e ${mini_iso} ]

then

wget “http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/current/legacy-images/netboot/${mini_iso}”

fi
rm -rf ${dist_dir}*

7z x ${server_iso} -o${dist_dir}-tmp install/hwe-netboot/ubuntu-installer/amd64/linux

7z x ${server_iso} -o${dist_dir}-tmp install/hwe-netboot/ubuntu-installer/amd64/initrd.gz

7z x ${server_iso} -o${dist_dir} EFI

7z x ${mini_iso} -o${dist_dir}

mv ${dist_dir}-tmp/install/hwe-netboot/ubuntu-installer/amd64/linux ${dist_dir}/linux

mv ${dist_dir}-tmp/install/hwe-netboot/ubuntu-installer/amd64/initrd.gz ${dist_dir}/initrd.gz

zip -r ${dist_dir}.zip ${dist_dir}

$ chmod +x customiso.sh

Run the script:

$ ./customish.sh

Now if you do a ls you will see three new files and a two new directories. The two important files to verify are ubuntu-20.04.1-legacy-server-amd64.iso, mini.iso, and a the new directory called ubuntu-20.04-netinstall.

Time to verify the sha of your .iso files. to do this run the sha256sum command on both files:

$ sha256sum mini.iso

0e79e00bf844929d40825b1f0e8634415cda195ba23bae0b041911fde4dfe018  mini.iso

$ sha256sum ubuntu-20.04.1-legacy-server-amd64.iso

f11bda2f2caed8f420802b59f382c25160b114ccc665dbac9c5046e7fceaced2  ubuntu-20.04.1-legacy-server-amd64.iso

Now its time to make a custom ISO using the mkisofs command. If you do not have the command. You can download cdrtools through your package manager.

What I did was run

$ mkisofs -o ubuntu-20.04-netinstall.iso \
and this should give you a prompt to run the rest of the commands:

> -b ubuntu-20.04-netinstall/isolinux.bin 

> -c ubuntu-20.04-netinstall/boot.cat 

> -no-emul-boot 

> -boot-load-size 4 

> -boot-info-table -J -R -V 

> UbuntuMinimal .

After completing the previous step, you should now see another file in your directory called ubuntu-20.04-netinstall.iso.

We now need to burn this iso onto our USB drive. Lets verify the name of our USB stick first with:

$ lsblk

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS

sda      8:0    0 931.5G  0 disk

├─sda1   8:1    0     1G  0 part /boot

├─sda2   8:2    0    30G  0 part /

└─sda3   8:3    0 900.5G  0 part /home

sdb      8:16   1  14.6G  0 disk

Be careful to make sure you recognize the proper block device name for your USB. In the picture above my USB is listed as sdb. If you are unsure what the block device name of your USB stick is called, you can run the lsblk command without the USB inserted in your PC and compare the differences to see what NAME is added.

Lets actually burn the ISO onto our USB now using the command dd.

WARNING: YOU CAN DELETE YOUR OS IF YOU TYPE IN THE INCORRECT BLOCK DEVICE NAME

$ dd bs=4M if=ubuntu-20.04-netinstall.iso of=/dev/sdb status=progress

Once this is completed it’s now time to boot your USB stick. I am going to assume you are installing REMnux onto another device. So lets plug in the USB stick into a USB port on the device you’d like to install Ubuntu on.

DISCLAIMER: I am going to assume that you have the knowledge about setting your boot order, and GRUB, so a few steps here will be skipped.

When I personally plugged in my USB I was getting an error that my PC could not find a bootable device when my USB stick was set to #1 in my boot order. I seen that this was not an issue with other people trying to boot a minimal Ubuntu iso with UEFI. If you are having the same issue as me, and already have grub installed, go back into your BIOS and set GRUB as #1 in your boot order.

Once you see Grub pop up, depending on what is on your screen you will need to do a few steps differently

Personally I previously had Arch installed on this device so I type in c to get to the grub terminal. If this is the case. We will need to type in a few commands to get the Ubuntu Installer to run. First lets list our devices.

grub> ls

Depending on your previous setup and partitions this could look a bit differnt. In my case my output of ls looked like this:

(hd0) (hd1) (hd1,gpt3) (hd1,gpt2) (hd1,gpt1) (hd2)

If you are not positive on which device is your USB, once again you can unplug your usb device. Load up the grub terminal and perform a ls and see what device is missing. Pay close attention to the devices listed with ,gptX in them as they can give you a hint. For example if I remove my USB and perform a ls my output would look like this:

(hd0) (hd0,gpt3) (hd0,gpt2) (hd0,gpt1) (hd1)

As you can see the hdX number changes based on the order its listed and not the actual device itself. I can see that when my USB stick in inserted it is listed as (hd0) since the hdX,gptX) devices change numbers, and the trailing (hdX) also changes numbers. So now lets boot into our Ubuntu install:

grub> set root=(hd0)

grub> linux /ubuntu-20.04-netinstall/linux

grub> initrd /ubuntu-20.04-netinstall/initrd.gz

grub> boot

This will bring up the Ubuntu Installer. To finish the remnux install I will direct you to the Remnux.org website as they already have a detailed writeup on the correct steps to take.

Remnux Docs