Also there's now a bigger problem: that you cannot tell when the copy failed because the file exists, or because any other reason.

People will just use:
cp --no-clover $in $out || true

But if it fails for any other reason, cross your fingers.

Hence now the option, in practice, is useless. Nobody should be using it.


On Sat, 1 Apr 2023 at 03:41, Alberto Salvia Novella <es20490446e@gmail.com> wrote:
Or use:
cp --no-clover $in $out || true

But again, surprising behavior. Just a new special case to memorize.

On Sat, 1 Apr 2023 at 03:36, Alberto Salvia Novella <es20490446e@gmail.com> wrote:
I get the impression that right now --no-clover is optimized for the less common scenarios, while making it less useful for the common ones.

Also --update isn't a substitute of --no-clover. As --no-clover is for copying when the file is missing, not when it isn't updated.

For example imagine that I have a config template, and a script copies the template only if it is missing using --no-clover.

If I did the same with --update it could happen the following: the package that provides the template updates, then --update will override the config even if it exists, just because the source file is now newer. No good.

So right now the only option that I have is to avoid both --no-clover and --update all together, and to test for the file existence separately. So totally useless.

On Sat, 1 Apr 2023 at 01:29, Paul Eggert <eggert@cs.ucla.edu> wrote:
On 2023-03-31 14:32, Pádraig Brady wrote:

> Perhaps we should support:
>    --no-clobber[={skip, fail (default)}]
>
> so then users can at least easily change -n to --no-clobber=skip
> to get the old behavior?
>
> An alternative would be to augment the --update option to support:
>    --update[={none, older (default)}]
> where --update=none would be the equivalent of the old -n behavior.

The latter sounds a bit better but I suppose either would work. We could
generalize it a bit further, e.g.:

   --skip-diagnose[={yes,no}]
      Whether to diagnose a copying action being skipped.
   --skip-fail[={yes,no}]
      Whether exit status should be 1 when skipping a copying action.

Presumably similar options would apply to ln and mv.

All these extra options might be overkill, though.


> Perhaps we should also diagnose files skipped in the -n fail case,
> to make it easier for users to see what the issue is.

FreeBSD cp -n doesn't diagnose, and GNU cp -n has never diagnosed, so
it's probably better to leave sleeping dogs lie.