Create grub2 floppy images with ease - opinionated, paths for debian-installed grub hard-coded

grub2-mkfloppy

#!/bin/sh -eu

keeptemporary=""
outfile="floppy.img"
modules=""
modules_default="biosdisk part_msdos fat multiboot configfile ls cat help"

help() {
    cat <<EOF
Usage: $0 -o outfile.img -m vbe -m multiboot

OPTIONS
    -h  Show help (this help you are reading right now)
    -o  Set output file
    -m  Add a module, if given, only the given modules (and their dependencies
        are added, otherwise a default set of modules is installed)
    -k  Keep temporary files

DEFAULT MODULES
    $modules_default

Be gay, do crime
EOF
}

while getopts ko:m:h arg; do
    case $arg in
        o)
            outfile=$OPTARG
            ;;
        m)
            modules="$modules $OPTARG"
            ;;
        k)
            keeptemporary=blacklivesmatter # we just need any string
            ;;
        *|h)
            help
            exit 0
            ;;
    esac
done

if [ -z "$modules" ]; then
    modules="$modules_default"
fi

outdir="$(dirname "$outfile")"
grub_img="$outdir/$(basename "$outfile" .img)-grub.img"

grub-mkimage -p /grub -C auto -O i386-pc -o "$grub_img" $modules
size=$(ls --block-size=512 -s "$grub_img" | sed 's/\s.*$//')

dd if=/dev/zero of="$outfile" bs=512 count=2880
dd if=/usr/lib/grub/i386-pc/boot.img of="$outfile" conv=notrunc
dd if="$grub_img" of="$outfile" conv=notrunc seek=1

mformat -i "$outfile" -kR $(($size + 2))
mmd -i "$outfile" grub

foxfile=$(mktemp -p "$outdir" README.foxXXXX)
cat >"$foxfile" <<EOF
Image built with grub2-mkfloppy. Be gay, do crimes, be you, be happy
    (not all required, your choice)

Modules included: $modules

For help query LittleFox on libera/#osdev
For comments about this being political, go talk to a tree.
EOF

mcopy -i "$outfile" "$foxfile" ::/README.fox

if [ -z "$keeptemporary" ]; then
    rm "$grub_img" "$foxfile"
fi