Ubuntu mini.iso with UEFI support

ubuntu-mini-iso-uefi

#!/bin/sh -eu

# Downloads, verifies and unpacks Ubuntu mini.iso fixing lack of UEFI support
# See https://bugs.launchpad.net/ubuntu/+source/debian-installer/+bug/1429030
# Thanks to https://www.nemotos.net/?p=2057

require() {
  hash "$@" || die "Some of the required commands are missing"
}

download() {
  echo "Downloading image"
  curl -f --fail-early --create-dirs -o "$image" -OO \
      "$image_url" "$checksums_url" "$checksums_url".gpg
}

verify() {
  echo "Verifying image"
  gpg --verify "$checksums".gpg "$checksums" || die "Signature verification failed" \
      "See https://ubuntu.com/tutorials/how-to-verify-ubuntu#4-retrieve-the-correct-signature-key"
  sha256sum -c --ignore-missing "$checksums" || die "Checksum verfication failed"
}

unpack() {
  echo "Unpacking image to $dist/"
  7z x -o"$dist" "$tempdir/$image"
  7z x -o"$dist" "$dist/boot/grub/efi.img"
}

die() {
  printf >&2 '%s\n' "$@"
  exit 1
}

! [ $# -eq 1 ] && die "Usage: $0 <dist>"

require 7z curl gpg sha256sum

dist=$1
base_url=http://archive.ubuntu.com/ubuntu/dists/$dist/main/installer-amd64/current

case $dist in
  precise|trusty|xenial|bionic|eoan)
    base_url=$base_url/images
    ;;
  *)
    base_url=$base_url/legacy-images
esac

image=netboot/mini.iso
image_url=$base_url/$image
checksums=SHA256SUMS
checksums_url=$base_url/$checksums
tempdir=$(mktemp -d mini.iso.XXXXXXXXXX) && trap 'rm -rf "$tempdir"' EXIT

(cd "$tempdir" && download && verify) && unpack

Need to use this for focal:

base_url=http://archive.ubuntu.com/ubuntu/dists/${dist}/main/installer-amd64/current/legacy-images

@BLuFeNiX Thanks, I've updated the URL in the script