First, I created a temporary working directory.
> mkdir /tmp/mbe > cd /tmp/mbe > touch .emacs > touch example.dart Contents of init file:
;; /tmp/mbe/.emacs (package-initialize) (setq package-archives '(("gnu"."https://elpa.gnu.org/packages/") ("nongnu"."https://elpa.nongnu.org/nongnu/"))) (let ((my-pkgs '(dart-mode))) (when (seq-remove'package-installed-p my-pkgs) (package-refresh-contents) (mapc (lambda (pkg) (package-install pkg t)) my-pkgs)))Contents of Dart file:
// /tmp/mbe/example.dartvoidmain() {}Then I ran the following:
> HOME=$(pwd) > emacs example.dart 