Re: Any way to allow clobbering empty files when noclobber is set?

[Bart Schaefer <schaefer@brasslantern.com>]

(Martin, if you are no longer interested in these side discussions, we
can stop Cc'ing you.)

On Thu, Jun 4, 2020 at 8:10 PM Daniel Shahaf <d.s@daniel.shahaf.name> wrote:
>
> Bart Schaefer wrote on Wed, 03 Jun 2020 22:00 -0700:
> > Fair enough, although (silly example) "false > empty" would remove the
> > file?
>
> Depends on whether ./empty was created by the redirection or not.

Hm.  That means that the following must all be preserved (in the
parent shell, so fails for "exec command > file") all the way from the
redirection event to the completion of the command:
 - whether the descriptor resulted from redirection
 - what kind of redirection operator was used
 - whether the appropriate clobber-related option was set at the time
 - how to identify the file we opened, in case something else renamed
or removed it, and created another one of the same name in the
meantime

That seems at least impractical, especially the last one.  And what
happens in the case of rename?

> Besides, if the redirection failed — I assume you mean the open(2)
> failed — then isn't the unlink likely to fail as well?

Open could fail because of file permissions.  Unlink depends only on
directory permissions.

> Okay.  Is there a case where leaving around an empty file is worse than
> removing it?

IMO your examples are all too specific to warrant a generalized change
in behavior of redirections.