initrd extraction commands for ubuntu 23.10 and above

 You can use the following steps to unpack and repack

This is initrd-extraction for ubuntu24.04
# Extract and prepare the working directories
# -------------------------------------------
mkdir /initrd-extraction
mkdir /initrd-extraction/extracted
cp initrd /initrd-extraction
cd /initrd-extraction
unmkinitramfs initrd  /extracted
cd extracted
# Add the first microcode firmware
# --------------------------------
cd early
find . -print0 | cpio --null --create --format=newc > ../../newinitrd
# Add the second microcode firmware
# ---------------------------------
cd ../early2
find kernel -print0 | cpio --null --create --format=newc >> ../../newinitrd
cd ../early3
find . -print0 | cpio --null --create –format=newc >> ../../newinitrd
# Add the ram fs file system
# --------------------------
cd ../main
find . | cpio --create --format=newc | xz --format=lzma >> ../../newinitrd
Finally rename newinitrd to initrd