• Using nix-shell for package development

Fire up your NixOS workhose and let's get to work:

# Fetch all the goodies
git clone -b devel https://github.com/vpsfreecz/vpsadminos
cd vpsadminos && git clone -b vpsadminos_dev https://github.com/vpsfreecz/nixpkgs

# set $NIX_PATH so that we have <nixpkgs/..> and <vpsadminos/...> both working:
export NIX_PATH="nixpkgs=`pwd`/nixpkgs:vpsadminos=`pwd`"

# Create temporary unpack path and jump to it
mkdir -p ~/tmp/kernel-dev; cd ~/tmp/kernel-dev

# Enter nix-shell with the package environment
nix-shell -E "with import <nixpkgs> {}; callPackage <vpsadminos/os/packages/linux/default.nix> {}"

# unpack the sources
unpackPhase

# rest of the phases
patchPhase
configurePhase
buildPhase
checkPhase
installPhase
fixupPhase
installCheckPhase
distPhase