14 Aug 2026

(macOS) Suppress annoying `xcrun` popup

macOS puts a stub at /usr/bin/python3 (and friends) that shells out to xcrun to find the real binary. If Xcode Command Line Tools aren't installed, this triggers an annoying GUI popup - which I really don't want since I manage everything through Nix devShells and avoid impure global installs.

I looked at the manpage, and found that xcrun respects the envvar DEVELOPER_DIR, and wondered if pointing this envvar to a stub xcrun could suppress the popup.

let
# Suppress annoying `xcrun` popups
stubDeveloperDir = "${pkgs.linkFarm "stub-developer-dir" [
    {
      name = "usr/bin/xcrun";
      path = pkgs.writeShellScript "stub-xcrun" ''
        >&2 echo "$1: command not found"
        exit 127
      '';
    }
  ]}";
in
...
environment = {
  shells = [ pkgs.bash ];
  variables = {
    DEVELOPER_DIR = stubDeveloperDir;
  };
};
launchd.user.envVariables = {
  DEVELOPER_DIR = stubDeveloperDir;
};

And voila!

$ python3
python3: command not found