Script to add kernels in /boot (or another EFI directory) to efibootmgr.

update-efibootmgr.sh

#!/bin/bash

# update-efibootmgr.sh
# Update UEFI boot entries using efibootmgr
# TODO: remove old entries, could use efibootmgr -v?

set -eu
set -o pipefail

distro="Funtoo Linux"
efidir="/boot"
partuuid=$(blkid -o value $(findmnt / -o source | tail -n1) | tail -n1)
disk=$(findmnt --target=/boot -o source | tail -n1)
part=${disk##*/}
part=${part#*sd[a-z]}
disk=${disk%[1-9]*}

for kernel in ${efidir}/vmlinuz*; do # Add kernels in $efidir
    kernel=${kernel#${efidir}/}
    efibootmgr -q -c -d ${disk} -p ${part} -L "${distro} ${kernel#vmlinuz-}" \
        -l /${kernel} -u root=PARTUUID=${partuuid} rw
    efibootmgr -q -c -d ${disk} -p ${part} -L "${distro} ${kernel#vmlinuz-} (Rescue)" \
        -l /${kernel} -u root=PARTUUID=${partuuid} rw init=/bin/bash
done

efibootmgr # print boot entries