What about making it a behavior we can toggle?

-o won't create a file if it doesn't get any data, but -O will, or
something like that?

I can see how both could be handy.

- Marc Doughty
"If you aren't sure who is the give-way vessel, you are the give-way
vessel."

On Thu, Aug 20, 2015 at 6:14 PM, Daniel Stenberg <daniel_at_haxx.se> wrote:

> Hi friends!
>
> In curl 7.42.0 we made curl capable of "transfering" zero byte files. It
> basically means that it actually creates a zero byte file when you do
>
> $ curl [URL] -o output
>
> ... and the URL successfully returns a file with no content. This was one
> of those silly things we've carried with us since forever and came out of
> the fact that the code for -o that writes data only ever opened the file
> and wrote something when data arrived and for a zero byte file of course no
> data came.
>
> So, commit 261a0fedc brought this feature.
>
> I've since realized that this introduced some interesting side-effects
> that surprise users. Now suddenly all those users who got a zero byte file
> back and were _happy_ with that gets an empty file that they don't need.
> Like when you do:
>
> $ curl -H "If-None-Match: blala" [URL] -o output
>
> ... or other variations of HTTP that gets a HTTP error response back with
> no body. This breaks scripts that previously could just check if 'output'
> was created to see if curl actually got something or not.
>
> So, I'm a bit stuck in a tough place. The previous behavior surprised a
> set of users and so does the new. Further, I could possibly make non-2xx
> codes not store zero byte files, but should -o behavior really care about
> HTTP response codes and won't that just be even harder to explain and for
> users to figure out?
>
> I hesitate to even suggest it (because of the option bloat we already
> suffer from), but does it need another command line option to get this
> solved for both sets of use cases?
>
> I could really use some fresh ideas and opinions. Especially if you use
> one of these versions! Tell me what you think!
>
> --
>
> / daniel.haxx.se
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Received on 2015-08-23