bug#31220: 25.3; emacs --script breaks command-line arguments handling

[Phil Sainty]

On 2018-04-20 08:00, Thibault Polge wrote:
> When running an Emacs Lisp script with either the `#!emacs --script`
> shebang or by invoking `emacs --script script.el`, Emacs:
>
> 1. immediately processes command-line arguments it knows, even if they
>    were passed *after* --script.  It means, for example, that no script
>    can provide a meaningful --help script, because Emacs always
>    intercepts help.

Writing elisp scripts is fiddly, but it *is* possible to handle
arbitrary arguments cleanly.

As with many programs, you can use the argument '--' to tell Emacs not
to process further arguments as if they were options. e.g.:

$ emacs --script -- --help

Which will pass '--' and '--help' to the script.


Some boiler-plate for an elisp script is:

#!/bin/sh
":"; exec emacs -Q --script "$0" -- "$@" # -*-emacs-lisp-*-
(pop argv) # Remove the "--" argument
# ...
# Always exit explicitly. This returns the desired exit
# status, and also avoids the need to (setq argv nil).
(kill-emacs 0)


For more information see:

* https://stackoverflow.com/a/6259330/324105
* https://swsnr.de/posts/emacs-script-pitfalls