package-update-all from command line

[Sam Steingold <sds@gnu.org>]

I would like to be able to update packages from the command line, and
thanks to Lars, I now can do

--8<---------------cut here---------------start------------->8---
emacs -batch -funcall package-initialize -load ~/.emacs.elc -funcall package-update-all
--8<---------------cut here---------------end--------------->8---

Alas, this has two problems:

1. It prints "No packages to update" even though M-x list-packages RET
reports "Packages that can be upgraded: 3; type ‘U’ to mark for upgrading".

2. Loading ~/.emacs.elc is relatively slow (e.g., because it fetches a
remote `remember-data-file'). so I would rather use something smaller.

After much experimentation, it turned out that this is what I need:

--8<---------------cut here---------------start------------->8---
emacs -batch -load package -load ~/.config/emacs/package-quickstart.elc \
  -eval '(setq package-selected-packages (delete-dups package-activated-list))' \
  -eval '(push (quote ("melpa" . "https://melpa.org/packages/")) package-archives)' \
  -eval '(package-update-all nil)'
--8<---------------cut here---------------end--------------->8---

Note that I had to specify the `QUERY` argument to `package-update-all'
explicitly, otherwise it asked me "3 packages to update.  Do it?(yes or no)"

I wonder if this feature is working as intended, or maybe there is a way
to make it nicer.
E.g., I would like to save `package-archives' in
`package-quickstart-file' so that I won't have to specify it on the
command line (it is set in ~/.emacs, of course).

Thanks.

-- 
Sam Steingold (http://sds.podval.org/) on Pop 22.04 (jammy) X 11.0.12101003
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