optools/sys/BootSync/sample.config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!-- This example assumes Grub2 and UEFI. It should be flexible enough to tweak for other use cases
     if you know what the hell you're doing. -->
<!--
SEE prep.txt FOR WHAT MUST BE DONE BEFORE RUNNING BOOTSYNC.
-->
<bootsync xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns="http://git.square-r00t.net/OpTools/tree/sys/BootSync/"
          xsi:schemaLocation="http://git.square-r00t.net/OpTools/plain/sys/BootSync/bootsync.xsd">
    <!-- The actual EFI System Partitions (ESP). At least two are required. -->
    <!-- Each drive should be prepared ahead of time with efibootmgr and grub-install (see prep.txt). -->
    <partitions>
        <!-- These should all be unique values.
             Don't do something dumb like mount the same partition on the same mountpoint. -->
        <!-- Future versions of this script may support things like UUIDs or labels as an alternative to path=,
             but in the meanwhile it relies on device paths explicitly. -->
        <part path="/dev/sdb1" mount="/mnt/boot1"/>
        <part path="/dev/sdd1" mount="/mnt/boot2"/>
    </partitions>
    <!--
         If fileChecks isn't provided, we will still sync syncPaths (which IS required).
         These files will be evaluated to and synced to the ESP partitions with the same relative path.
         i.e. (part[@mount])/(file)

         fileChecks[@hashtype] attribute is used to checksum all <file> children,
         unless they specify their own hashtype attribute (the default is hashtype="md5" for speed optimizations).

         Guaranteed valid hashtype values are:

            sha1
            sha224
            sha256
            sha384
            sha512
            blake2b
            blake2s

         If you have a non-FIPS-compliant Python (you very most likely do), the following hashtype is also available:

            md5

         If you have a recent enough OpenSSL (and python3), you have the additional hashtype values available:

            sha3_224
            sha3_256
            sha3_384
            sha3_512
            shake_128
            shake_256

         Additionally, the value "false" is always available to disable hashing for a specific <file> object or to set
         the default. No checksumming will be done in this case and the file will always be overwritten on every run.

         This is *highly not recommended* for solid-state disks or if you have large files you plan on syncing to
         the alternate ESPs (e.g. loop-mounted ISO/IMG files).

         "isKernel" is by default false, but if true it is treated specially to get a kernel version.
         This is to notify you if a reboot is required. If no <file> item is isKernel="true", no reboot requirement
         detection will be done.
         Only *the last* <file> with isKernel="true" listed is used as the kernel identifier.
    -->
    <fileChecks hashtype="sha1">
        <!-- RELATIVE paths to /boot on your / mount. -->
        <file>initramfs-linux.img</file>
        <file>intel-ucode.img</file>
        <file>memtest86+/memtest.bin</file>
        <file isKernel="true" hashtype="sha512">vmlinuz-linux</file>
    </fileChecks>
    <!--
        These are system paths to sync to the ESPs. They are synced recursively.

            "hashtype" is also supported for syncPaths and path objects just as the same with fileChecks
            and file objects (see above).

            "source" should be absolute.
            "target" should be relative (to the ESP mount).
            "pattern" is a regex to match to restrict *filenames* to sync. Use ".*" for all files.
    -->
    <syncPaths hashtype="sha1">
        <!-- For example, these are grub theme files. -->
        <path source="/usr/share/grub/themes" target="grub/themes" pattern=".*"/>
        <!-- These are grub modules - specifically, UEFI. -->
        <path source="/usr/lib/grub/x86_64-efi" target="grub/x86_64-efi" pattern="^.*\.(mod|lst|sh)$"/>
        <!-- And these are ISO files, in case you're like me and do loop mounting in Grub for rescue situations.
             (e.g. https://wiki.archlinux.org/index.php/Multiboot_USB_drive#Using_GRUB_and_loopback_devices) -->
        <path hashtype="false" source="/boot/iso" target="iso" pattern="^.*\.(iso|img)$"/>
    </syncPaths>
</bootsync>