diskimage-builder/diskimage_builder/elements/iso/post-install.d/01-copy-bootloaders

#!/bin/bash

if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
    set -x
fi

set -eux
set -o pipefail

TMP_BOOTLOADER_DIR=/tmp/bootloader_files
mkdir -p $TMP_BOOTLOADER_DIR

if [ $DISTRO_NAME = "fedora" ]; then
    GRUB_FILE="/boot/efi/EFI/fedora/grubx64.efi"
else
    GRUB_FILE="/usr/lib/grub/x86_64-efi-signed/grubx64.efi.signed"
fi

if [ $DISTRO_NAME = "fedora" ]; then
    SHIM_FILE="/boot/efi/EFI/fedora/shim.efi"
else
    SHIM_FILE="/usr/lib/shim/shim.efi.signed"
fi

#fedora
if [ $DISTRO_NAME = "fedora" ]; then
    SYSLINUX_FILE="/usr/share/syslinux/isolinux.bin"
    LDLINUX_FILE="/usr/share/syslinux/ldlinux.c32"
#debian
elif [ $DISTRO_NAME = "debian" ]; then
    SYSLINUX_FILE="/usr/lib/ISOLINUX/isolinux.bin"
    LDLINUX_FILE="/usr/lib/syslinux/modules/bios/ldlinux.c32"
#ubuntu
else
    SYSLINUX_FILE="/usr/lib/syslinux/isolinux.bin"
    LDLINUX_FILE="/usr/lib/syslinux/ldlinux.c32"
fi

cp $GRUB_FILE $TMP_BOOTLOADER_DIR
cp $SHIM_FILE $TMP_BOOTLOADER_DIR
cp $SYSLINUX_FILE $TMP_BOOTLOADER_DIR

# Starting from SYSLINUX 5.00, the isolinux.bin is dependent
# on ldlinux.c32.
# http://www.syslinux.org/wiki/index.php/Library_modules
if [ -f "$LDLINUX_FILE" ]; then
    cp $LDLINUX_FILE $TMP_BOOTLOADER_DIR
fi