mkinitrd

A handy way to run a program as init without a filesystem:

#! /bin/bash

set -e
set -u
set -x

rm -rf initrd/
mkdir initrd/
g++ -static [...] -o initrd/init main.cc

(cd initrd/ && (find | cpio -o -H newc)) \
        | gzip -c \
        > initrd.gz