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File overwritten with HTTP/1.1 304 Not Modified

From: Paul Gilmartin via curl-users <curl-users_at_cool.haxx.se>
Date: Sat, 31 Aug 2019 11:52:57 -0600

Hello, Curlers,

On MacOS: 566 $ uname -a
Darwin PaulGilm.wifi.belezacoffeebar.com 18.7.0 Darwin Kernel Version 18.7.0: Tue Aug 20 16:57:14 ...
With Curl: 567 $ curl -V
curl 7.54.0 (x86_64-apple-darwin18.0) libcurl/7.54.0 LibreSSL/2.6.5 zlib/1.2.11 nghttp2/1.24.1 ...

I try:
ifcurl 31+ curl --location --fail --show-error --header 'If-None-Match: "1541025663+ident"' --header 'Host: example.com' --header 'From: PaulGBoulder@AIM.com' --dump-header example.com.headerstmp --output example.com http://example.com

... and receive headers:
571 $ cat *headers
HTTP/1.1 304 Not Modified
Cache-Control: max-age=604800
Date: Sat, 31 Aug 2019 17:44:55 GMT
Etag: "1541025663+ident"
Expires: Sat, 07 Sep 2019 17:44:55 GMT
Last-Modified: Fri, 09 Aug 2013 23:54:35 GMT
Server: ECS (dna/63B4)
Vary: Accept-Encoding
X-Cache: HIT

*however* my --output file is overwritten with an empty file.
I'd prefer that this not happen.

Is there a combination of options that preserves the file in case of 304?
Should I consider this a bug?

I believe an earlier release of curl on Raspberry Pi did not overwrite.

I understand that in case of some errors, such as 404, the user prefers
to receive the file.

Thanks,
gil

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Received on 2019-08-31