FM / install.d

/usr/lib/kernel/install.d

Name	Size	Mode	Actions
10-devicetree.install	1962	0755	edit dl rm
20-grub.install	8586	0755	edit dl rm
20-grubby.install	1905	0755	edit dl rm
50-depmod.install	2297	0755	edit dl rm
50-dracut.install	2149	0755	edit dl rm
51-dracut-rescue.install	3880	0755	edit dl rm
60-kdump.install	791	0755	edit dl rm
90-loaderentry.install	5907	0755	edit dl rm
90-uki-copy.install	3387	0755	edit dl rm
92-crashkernel.install	204	0755	edit dl rm
95-kernel-hooks.install	675	0755	edit dl rm
99-grub-mkconfig.install	1045	0755	edit dl rm

Edit: /usr/lib/kernel/install.d/51-dracut-rescue.install (3880B)

#!/usr/bin/bash

export LANG=C

COMMAND="$1"
KERNEL_VERSION="$2"
BOOT_DIR_ABS="${3%/*}/0-rescue"
KERNEL_IMAGE="$4"

dropindirs_sort()
{
    suffix=$1; shift
    args=("$@")
    files=$(
        while (( $# > 0 )); do
            for i in "${1}"/*"${suffix}"; do
                [[ -f $i ]] && echo "${i##*/}"
            done
            shift
        done | sort -Vu
    )

for f in $files; do
        for d in "${args[@]}"; do
            if [[ -f "$d/$f" ]]; then
                echo "$d/$f"
                continue 2
            fi
        done
    done
}

[[ -f /etc/os-release ]] && . /etc/os-release

if [[ ${KERNEL_INSTALL_MACHINE_ID+x} ]]; then
    MACHINE_ID=$KERNEL_INSTALL_MACHINE_ID
elif [[ -f /etc/machine-id ]] ; then
    read -r MACHINE_ID < /etc/machine-id
fi

if ! [[ $MACHINE_ID ]]; then
    exit 0
fi

if [[ -f /etc/kernel/cmdline ]]; then
    read -r -d '' -a BOOT_OPTIONS < /etc/kernel/cmdline
elif [[ -f /usr/lib/kernel/cmdline ]]; then
    read -r -d '' -a BOOT_OPTIONS < /usr/lib/kernel/cmdline
else
    declare -a BOOT_OPTIONS

read -r -d '' -a line < /proc/cmdline
    for i in "${line[@]}"; do
        [[ "${i#initrd=*}" != "$i" ]] && continue
        BOOT_OPTIONS+=("$i")
    done
fi

if [[ -d "${BOOT_DIR_ABS%/*}" ]]; then
    BOOT_DIR="/${MACHINE_ID}/0-rescue"
    BOOT_ROOT=${BOOT_DIR_ABS%$BOOT_DIR}
    LOADER_ENTRY="$BOOT_ROOT/loader/entries/${MACHINE_ID}-0-rescue.conf"
    KERNEL="linux"
    INITRD="initrd"
else
    BLS_DIR="/boot/loader/entries"
    BOOT_DIR_ABS="/boot"
    LOADER_ENTRY="$BLS_DIR/${MACHINE_ID}-0-rescue.conf"
    KERNEL="vmlinuz-0-rescue-${MACHINE_ID}"
    INITRD="initramfs-0-rescue-${MACHINE_ID}.img"
fi

ret=0

case "$COMMAND" in
    add)
        [[ -f "$LOADER_ENTRY" ]] && [[ -f "$BOOT_DIR_ABS/$KERNEL" ]] \
            && [[ -f "$BOOT_DIR_ABS/$INITRD" ]] && exit 0

# source our config dir
        for f in $(dropindirs_sort ".conf" "/etc/dracut.conf.d" "/usr/lib/dracut/dracut.conf.d"); do
            if [[ -e $f ]]; then
                # shellcheck disable=SC1090
                . "$f"
            fi
        done

# shellcheck disable=SC2154
        [[ $dracut_rescue_image != "yes" ]] && exit 0

[[ -d "$BOOT_DIR_ABS" ]] || mkdir -p "$BOOT_DIR_ABS"

if ! cp --reflink=auto "$KERNEL_IMAGE" "$BOOT_DIR_ABS/$KERNEL"; then
            echo "Can't copy '$KERNEL_IMAGE to '$BOOT_DIR_ABS/$KERNEL'!" >&2
        fi

HMAC=".${KERNEL}.hmac"

KERNEL_DIR="${KERNEL_IMAGE%/*}"
        KERNEL_FILE="${KERNEL_IMAGE##*/}"

HMAC_FILE="${KERNEL_DIR}/.${KERNEL_FILE}.hmac"

if ! sed -E "s/([0-9a-f]+)(\s+).*$/\1\2${KERNEL}/" "$HMAC_FILE" > "$BOOT_DIR_ABS/$HMAC"; then
            echo "Can't create '$BOOT_DIR_ABS/$HMAC' from '$HMAC_FILE'!" >&2
        fi

if [[ ! -f "$BOOT_DIR_ABS/$INITRD" ]]; then
            dracut -f --no-hostonly -a "rescue" "$BOOT_DIR_ABS/$INITRD" "$KERNEL_VERSION"
            ((ret+=$?))
        fi

if [[ "${BOOT_DIR_ABS}" != "/boot" ]]; then
            {
                echo "title      $PRETTY_NAME - Rescue Image"
                echo "version    $KERNEL_VERSION"
                echo "machine-id $MACHINE_ID"
                echo "options    ${BOOT_OPTIONS[*]} rd.auto=1"
                echo "linux      $BOOT_DIR/linux"
                echo "initrd     $BOOT_DIR/initrd"
            } > "$LOADER_ENTRY"
        else
            if [[ -e "${BLS_DIR}/${MACHINE_ID}-${KERNEL_VERSION}.conf" ]]; then
                cp -aT "${BLS_DIR}/${MACHINE_ID}-${KERNEL_VERSION}.conf" "$LOADER_ENTRY"
            else
                cp -aT "${KERNEL_IMAGE%/*}/bls.conf" "$LOADER_ENTRY"
            fi
            sed -i "s/${KERNEL_VERSION}/0-rescue-${MACHINE_ID}/" "$LOADER_ENTRY"
        fi

((ret+=$?))
        ;;

remove)
        exit 0
        ;;

*)
        usage
        ret=1;;
esac

exit $ret

cmd: