Rebuild an existing Ubuntu initrd/initramfs

rebuild-initrd.sh

#!/bin/bash
set -e

# 1. extract initrd with: unmkinitramfs initrd.img...-generic extracted
# 2. cd extracted
# 3. make changes
# 4. then execute this script to repack

if [ "$1" == "" ]; then
        echo "Enter target file name as first parameter!"
        exit 1
fi

cd early
find . -print0 | cpio --null --create --format=newc > "../$1"

cd ../early2
find . -print0 | cpio --null --create --format=newc >> "../$1"

cd ../early3
find . -print0 | cpio --null --create --format=newc >> "../$1"

cd ../main
find . -print0 | cpio --null --create --format=newc >> "../$1"