GNU bug report logs - #24287
Process filters received stderr output, not documented

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Package: emacs;

Reported by: "Paul A. Steckler" <steck <at> stecksoft.com>

Date: Mon, 22 Aug 2016 18:06:02 UTC

Severity: minor

Done: Eli Zaretskii <eliz <at> gnu.org>

Bug is archived. No further changes may be made.

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Message #11 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Clément Pit--Claudel <clement.pit <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Cc: Eli Zaretskii <eliz <at> gnu.org>
Subject: Re: bug#24287: Process filters received stderr output, not documented
Date: Mon, 22 Aug 2016 14:38:01 -0400
[Message part 1 (text/plain, inline)]
On 2016-08-22 14:23, Eli Zaretskii wrote:
>> From: "Paul A. Steckler" <steck <at> stecksoft.com>
>> Date: Mon, 22 Aug 2016 13:35:25 -0400
>>
>> The documentation for Process Filter Functions mentions that process
>> filters receive the standard output from their associated processes. It
>> does not mention that the filters also receive standard error output.
> 
> That is described in the parent section:
> 
>      It is impossible to separate the standard output and standard error
>   streams of the subprocess, because Emacs normally spawns the subprocess
>   inside a pseudo-TTY, and a pseudo-TTY has only one output channel.  If
>   you want to keep the output to those streams separate, you should
>   redirect one of them to a file—for example, by using an appropriate
>   shell command.

Still, even the parent section could be confusing:

       The output that a subprocess writes to its standard output stream is
                                                  ^^^^^^^^^^^^^^^
    passed to a function called the “filter function”.  The default filter
    function simply inserts the output into a buffer, which is called the
    associated buffer of the process (*note Process Buffers::).  If the process
    has no buffer then the default filter discards the output.

The highlighted section is not true, is it?

Clément.

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This bug report was last modified 8 years and 306 days ago.

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