Usage: callPackage [path] [...nix-build args]

callPackage

#!/usr/bin/env bash
#
# Usage: callPackage [src] [...nix-build args]
#
# A version of nix-build that uses nixpkgs.callPackage to fill in the
# arguments.
#
# * [src] can be a path or a URL. Defaults to .
#
# Example:
#
#   callPackage https://github.com/direnv/direnv/archive/master.tar.gz
#
# Let's say you are hacking on pkgs/applications/misc/hello/default.nix
# The problem is that default.nix takes a number of arguments and thus cannot
# be called with nix-build directly. So first you have to edit
# pkgs/top-level/all-packages.nix and figure out which attribute the package
# maps to, then call `nix-build -A hello` on the repo root.
#
# Instead, use `callPackage pkgs/applications/misc/hello/default.nix`. You
# might already be in the `pkgs/applications/misc/hello` folder in which case
# `callPackage` is enough.
set -uo pipefail

src=${1:-}
shift

exec nix-build \
  --no-out-link \
  -I "src=$src" \
  --expr '(import <nixpkgs> {}).callPackage <src> {}' \
  "$@"