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Re: «--etag-compare» while «--continue-at»

From: Коваленко Анатолий Викторович via curl-users <curl-users_at_cool.haxx.se>
Date: Sun, 10 May 2020 01:05:10 +0300

Please, read in the Wikipedia about «ETag».

> On Sat, 9 May 2020, at 11:09, Коваленко Анатолий Викторович via curl-users wrote:
>> You asked an example. My script saved (as JSON) history of
>> HTTP-headers while downloading with
>> breaks of provider's connection.
>> Page: http://get.opera.com/ftp/pub/opera/desktop/68.0.3618.63/win/
>> File:
>> http://get.opera.com/ftp/pub/opera/desktop/68.0.3618.63/win/Opera_68.0.3618.63_Setup_x64.exe
>> Call: curl.exe -C - -D Dump.txt -O -R -y 10 -Y 1024 $HRef
>>
>> You can see, that changed and restored for a short time (from
>> «05:12:42» to «08:19:29») values of
>> next parameters:
>> «ETag» (from «5ea97a29-38b5528» to «5ea97a2a-38b5528» and back);
>> «Last-Modified» (from «Wed, 29 Apr 2020 12:59:21 GMT» to «Wed, 29 Apr
>> 2020 12:59:22 GMT» and back);

> If the file being grabbed has changed while you've been trying to grab it,
> would this not make sense?

> Or, possibly the place you're grabbing it from keeps the file on several
> servers and the file timestamps are not all the same. Maybe some of your
> attempts were being serviced by one server and another attempt by a
> different server?

> (I'm only guessing. I have no idea if cURL is supposed to be able to tell
> if this were to happen. I can't see how cURL would know though if the
> server(s) at the far end don't say.)

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Received on 2020-05-10