Append preseed.cfg to Debian installer iso and generates a new iso.

ediso.sh

#!/usr/bin/env bash
#
# Usage:
# sudo ediso.sh patho_to/isofile.iso path_to/new_isofile.iso path_to/preseed_file
#
# Requires:
# - bsdtar
# - genisoimage
# - syslinux-utils

# Check if user is root...
if [[ $EUID -ne 0 ]]; then
   echo -e "Use 'sudo' to run this script!\n" 1>&2
   exit 1
fi

# Check if requirements are installed...

if [[ "$(command -v bsdtar)" == "" ]]; then
    echo "'bsdtar' not installed!"
    exit 1
fi

if [[ "$(command -v genisoimage)" == "" ]]; then
    echo "'genisoimage' not installed!"
    exit 1
fi

if [[ "$(command -v isohybrid)" == "" ]]; then
    echo "'syslinux-utils' not installed!"
    exit 1
fi

# Default extraction path...
tmp_dir="tmpiso"

# Extract original iso to temp dir...
echo -e "\n-- Extracting ISO to $tmp_dir..."
mkdir $tmp_dir
bsdtar -C "$tmp_dir/" -xf $1

# Detect iso archtecture - TODO: improve this!
[ -d "$tmp_dir/install.amd" ] && arch="amd"
[ -d "$tmp_dir/install.386" ] && arch="386"
echo "-- Detected achtecture: $arch"

# Unzip initrd.gz...
chmod -R +w "$tmp_dir/install.$arch"
echo "-- Extracting $tmp_dir/install.$arch/initrd.gz..."
gunzip "$tmp_dir/install.$arch/initrd.gz"

# Append preseed_file to initrd...
echo -e "-- Appending $3 to initrd... \c"
echo $3 | cpio -H newc -o -A -F "$tmp_dir/install.$arch/initrd"

# Zip initrd...
echo "-- Compressing initrd..."
gzip "$tmp_dir/install.$arch/initrd"
chmod -R -w "$tmp_dir/install.$arch"

# Fix md5sum.txt...
echo "-- Fixing md5sum.txt..."
cd $tmp_dir
md5sum $(find -follow -type f 2>/dev/null) > md5sum.txt
cd ..

# Generate new iso file...
echo -e "-- Generating iso file $2..."
rm $2 &> /dev/null
genisoimage -quiet -r -J -b isolinux/isolinux.bin \
            -c isolinux/boot.cat -no-emul-boot    \
            -boot-load-size 4 -boot-info-table    \
            -o $2 $tmp_dir
real_usr="$(logname)"
chown $real_usr:$real_usr $2

# Make iso bootable...
echo -e "-- Making $2 bootable..."
isohybrid $2

# Cleaning...
rm -fr $tmp_dir

echo -e "\nDone!\n"

exit 0