before building set Tempdir because of ramdisk size
export TMPDIR=/nix/persist/user/dominik/tmp/build-sdcard

# Raspberry Pi Multiroom audio client
- change hostname in sd-card.nix
- add wifi psk
- nix-build '<nixpkgs/nixos>' --cores 4 -A config.system.build.sdImage -I nixos-config=./sd-card.nix --argstr system aarch64-linux

# raspberry Pi Zero Mutliroom audio client
- change hostname in sd-card-zero.nix
- add wifi psk
- nix-build '<nixpkgs/nixos>' -A config.system.build.sdImage -I nixos-config=./sd-card-zero.nix --argstr system aarch64-linux