zz-update-systemd-boot

#!/bin/bash
#
# This is a simple kernel hook to populate the systemd-boot entries
# whenever kernels are added or removed.

# The UUID of your root "/" disk.
UUID="852b5870-0055-4d5b-91f7-101e5ead3b6f"

# Any rootflags you wish to set. For example, mine are currently
# "subvol=@ quiet splash intel_pstate=enable".
#ROOTFLAGS="subvol=@"

# Our kernels.
KERNELS=()
FIND="find /boot -maxdepth 1 -name 'vmlinuz-*' -type f -not -name '*.dpkg-tmp' -print0 | sort -Vrz"
while IFS= read -r -u3 -d $'\0' LINE; do
	KERNEL=$(basename "${LINE}")
	KERNELS+=("${KERNEL:8}")
done 3< <(eval "${FIND}")

# There has to be at least one kernel.
if [ ${#KERNELS[@]} -lt 1 ]; then
	echo -e "\e[2msystemd-boot\e[0m \e[1;31mNo kernels found.\e[0m"
	exit 1
fi

# Perform a nuclear clean to ensure everything is always in
# perfect sync.
rm /boot/efi/loader/entries/*.conf
rm -rf /boot/efi/ubuntu
mkdir /boot/efi/ubuntu

# Copy the latest kernel files to a consistent place so we can
# keep using the same loader configuration.
LATEST="${KERNELS[@]:0:1}"
echo -e "\e[2msystemd-boot\e[0m \e[1;32m${LATEST}\e[0m"
for FILE in config initrd.img System.map vmlinuz; do
    cp "/boot/${FILE}-${LATEST}" "/boot/efi/ubuntu/${FILE}"
    cat << EOF > /boot/efi/loader/entries/ubuntu.conf
title   Ubuntu
linux   /ubuntu/vmlinuz
initrd  /ubuntu/initrd.img
options root=UUID=${UUID} rw
EOF
done

# Copy any legacy kernels over too, but maintain their version-
# based names to avoid collisions.
if [ ${#KERNELS[@]} -gt 1 ]; then
	LEGACY=("${KERNELS[@]:1}")
	for VERSION in "${LEGACY[@]}"; do
	    echo -e "\e[2msystemd-boot\e[0m \e[1;32m${VERSION}\e[0m"
	    for FILE in config initrd.img System.map vmlinuz; do
	        cp "/boot/${FILE}-${VERSION}" "/boot/efi/ubuntu/${FILE}-${VERSION}"
	        cat << EOF > /boot/efi/loader/entries/ubuntu-${VERSION}.conf
title   Ubuntu ${VERSION}
linux   /ubuntu/vmlinuz-${VERSION}
initrd  /ubuntu/initrd.img-${VERSION}
options root=UUID=${UUID} rw
EOF
	    done
	done
fi

# reset the boot order so "ubuntu" comes first.  It's difficult to predict
# other entry situations, so we'll just focus on this one goal.  This assumes
# that the ubuntu boot option is "active" (has an asterisk after it).
curorder=`efibootmgr | grep ^BootOrder | cut -d" " -f2`
ubuntu=`efibootmgr | grep " ubuntu$" | cut -c5-8`
# remove the current ubuntu entry (3 ways) if present, and prepend ubuntu and trim more than 5th entry
tmporder=`echo $curorder | sed "s/,$ubuntu,/,/" | sed "s/$ubuntu,//" | sed "s/,$ubuntu//" | sed "s/^/$ubuntu,/" | cut -d"," -f1-5`
efibootmgr --bootorder $tmporder

# Success!
echo -e "\e[2m---\e[0m"
exit 0