rather primitive (for now) shell script to get a default.nix with some packages

nixify.sh

read -r -d '' TEMPLATE << EOM
with (import <nixpkgs> {});

stdenv.mkDerivation {
    name = "dev-shell";
    src = null;
    buildInputs = [ __PKGS__ ];
}
EOM

usage() {
    echo -e "Usage:\n\t $0 pkg1 pkg2 ... \n"
}

if [[ $# -ne 1 ]]; then
    echo -e "Error: No packages given!\n"
    usage
    exit 1
fi

PKGS="$*"
echo -e "$TEMPLATE" | sed -e "s/__PKGS__/${PKGS}/"

Can be used as follows:

$ ./nixify nodejs-8_x > shell.nix
$ nix-shell

sweet, it does not tie itself to a certain commit (yet), right? Which means it always depends on the local system, did I understand that correct?