Create Mini Linux System for Qemu Kernel Initrd

#!/bin/bash

start=$PWD
initramfs=${start}/initramfs
ARCH="x86_64"
ARCH2="x86"
linux="linux-6.0"
lv="$(echo $linux|cut -d\- -f2|cut -d\. -f1)"

mkdir $initramfs
cd $initramfs
mkdir -pv bin lib dev etc mnt/root proc root sbin sys
mknod -m 666 dev/null c 1 3
mknod -m 666 dev/tty c 5 0
mknod -m 666 dev/zero c 1 5
mknod -m 666 dev/random c 1 8

echo "nameserver 8.8.8.8" > etc/resolv.conf
echo "search 8.8.8.8" >> etc/resolv.conf

#Create INIT startup script
cat << EOS > init
#!/bin/sh

mknod -m 666 dev/null c 1 3
mknod -m 666 dev/tty c 5 0
mknod -m 666 dev/zero c 1 5
mknod -m 666 dev/random c 1 8

/bin/mount -t proc none /proc
/bin/mount -t sysfs sysfs /sys

cat <<'EOF'
 __  __ _       _   _     _
|  \/  (_)_ __ (_) | |   (_)_ __  _   ___  __
| |\/| | | '_ \| | | |   | | '_ \| | | \ \/ /
| |  | | | | | | | | |___| | | | | |_| |>  <
|_|  |_|_|_| |_|_| |_____|_|_| |_|\__,_/_/\_\

EOF
echo 'Enjoy your new mini system!'

/bin/sh
EOS

chmod 755 init


cd bin
wget -c "https://busybox.net/downloads/binaries/1.35.0-x86_64-linux-musl/busybox" -O busybox
chmod +x busybox

./busybox  --help | \
sed -e '1,/^Currently defined functions:/d' \
    -e 's/[ \t]//g' -e 's/,$//' -e 's/,/\n/g' | \
while read app ; do
  if [ "$app" != "" ]; then
    echo "linking ${app}..."
    ln -sf "./busybox" "$app"
    ls -ld "$app"
  fi
done

cd $initramfs
find . -print0 | cpio --null -ov --format=newc > ../initrd.cpio

cd $start
wget -c "https://www.kernel.org/pub/linux/kernel/v${lv}.x/${linux}.tar.xz"
tar xf ${linux}.tar.xz
cd ${linux}
make allnoconfig
#make menuconfig
make

cp arch/$ARCH2/boot/bzImage $start
cd $start
qemu-system-$ARCH -kernel bzImage -initrd initrd.cpio