#2030 sounds similar

The code that writes the error message has no clue where the write was done so it can't say "pipe" because it could've been a buffer or a file.

Would Failed writing response data to the intended destination be any better?

The code that writes the error message has no clue where the write was done so it can't say "pipe" because it could've been a buffer or a file.

Would Failed writing response data to the intended destination be any better?

Hello Badger, Yes, that sure sounds better, even better is to put Curl in the message. Saw saw this on a terminal, had no idea where it came from. Maybe "Curl failed to write data to destination" ?

May I ask, what is the exact writing error, EIO?

even better is to put Curl in the message

We can't do that, this is libcurl creating the error and libcurl is also used by hundreds of other applications than curl.

But really, curl already prefixes the error message with curl:, it doesn't look the way you showed it. See below for 7.68.0 and 7.71.0-DEV both show it when I try this:

$ curl localhost/512M | head -c 1
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0  512M    0  127k    0     0   124M      0  0:00:04 --:--:--  0:00:04  124M
curl: (23) Failed writing body (250 != 16384)

what is the exact writing error, EIO

In your particular use case it is fwrite() returning an error, but this error message is more general and the failed writing could also be a callback returning an error etc.

Is this better?

./src/curl localhost/512M | head -c 1
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0  512M    0 65286    0     0  31.1M      0  0:00:16 --:--:--  0:00:16 31.1M
curl: (23) Failed writing response data to the destination

Hello badger
Many thanks for working on this so quickly.

Yes, this looks better. My only feedback is in relation to the English. "the" is not necessary in the message. "Failure" is the way we would write in English. I'd probably leave out "data" as well

ie. "curl: Failure writing output to destination"

Any idea what the error code 23 is?

All curl error messages are shown like that. The number within parenthesis is the numerical error it returns.

Ah, ok, now I understand CURLE_WRITE_ERROR (23) I read here online:
https://curl.haxx.se/libcurl/c/libcurl-errors.html

I'd be happy to see CURLE_WRITE_ERROR or other error enum. Is that what curl_easy_strerror() returns?

The error codes from curl, the command line tool, is described in the man page for curl. At the end of it:

       23     Write error. Curl couldn't write data to a local filesystem or similar.

The error codes from curl, the command line tool, is described in the man page for curl. At the end of it:

       23     Write error. Curl couldn't write data to a local filesystem or similar.

Many thanks for your reply.

The difficulty is when the line appears in a log or stdout :

My program output
(23) Failed writing body
Other parts of my program output
Read file index.html

I can't figure-out where that came from, unless it has a "curl" prefix, as it all just went to stdout.
Is there anyway curl could identifyt it self? Generally unix programs output themselvs as the first part of the output line

eg

$ cd missing_dir
bash: cd: missing_dir: No such file or directory

Thank you again for making this change to improve this

Again: curl does this. Let me show you an example with curl 7.68.0:

$ curl localhost/512M | head -c 1
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0  512M    0  127k    0     0   124M      0  0:00:04 --:--:--  0:00:04  124M
curl: (23) Failed writing body (250 != 16384)

Again: curl does this. Let me show you an example with curl 7.68.0:

$ curl localhost/512M | head -c 1
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0  512M    0  127k    0     0   124M      0  0:00:04 --:--:--  0:00:04  124M
curl: (23) Failed writing body (250 != 16384)

I see, I'm sure it's a problem in my environment then. Thank you again for your reply. And developing such a useful tool!

any idea on how to resolve this?

Asking support question in an issue we closed a year ago is not the way at least.