Debian auto-installer

repack.sh

#!/bin/sh

orig_iso="$HOME/Downloads/debian-12.1.0-amd64-netinst.iso"
new_files="$HOME/Desktop/ISOFILES"
new_iso="$HOME/Desktop/debian-12.1.0-amd64-modified.iso"
mbr_template=isohdpfx.bin

mkdir -p $new_files

xorriso -osirrox on -indev $orig_iso -extract / $new_files

chmod +w -R ISOFILES/install.amd/
gunzip ISOFILES/install.amd/initrd.gz
echo preseed.cfg | cpio -H newc -o -A -F ISOFILES/install.amd/initrd
gzip ISOFILES/install.amd/initrd
chmod -w -R ISOFILES/install.amd/
cd ISOFILES
chmod +w md5sum.txt
find -follow -type f ! -name md5sum.txt -print0 | xargs -0 md5sum > md5sum.txt
chmod -w md5sum.txt
cd ..

# Extract MBR template file to disk
dd if="$orig_iso" bs=1 count=432 of="$mbr_template"

# Create the new ISO image
xorriso -as mkisofs \
   -r -V 'Debian 12.1.0 amd64 n' \
   -o "$new_iso" \
   -J -J -joliet-long -cache-inodes \
   -isohybrid-mbr "$mbr_template" \
   -b isolinux/isolinux.bin \
   -c isolinux/boot.cat \
   -boot-load-size 4 -boot-info-table -no-emul-boot \
   -eltorito-alt-boot \
   -e boot/grub/efi.img \
   -no-emul-boot -isohybrid-gpt-basdat -isohybrid-apm-hfsplus \
   "$new_files"