Re: BOM (byte order mark) in process stdout and stderr

[Eli Zaretskii]

> From: Jürgen Hötzel <address@hidden>
> Date: Thu, 25 Jun 2015 20:37:41 +0200
> Cc: address@hidden
> 
>     > (let ((default-process-coding-system '(utf-8-with-signature .
>     > utf-8-with-signature)))
>     > (start-file-process
>     > "BOM"
>     > (generate-new-buffer "*bom-test*")
>     > "~/tmp/Hello.exe"))
>     >
>     > This results in the following process-buffer (hexl-mode):
>     >
>     > 00000000: efbb bf53 5444 4f55 540a 5354 4445 5252 ...STDOUT.STDERR
>     > 00000010: 0a0a 5072 6f63 6573 7320 424f 4d20 6669 ..Process BOM fi
>     > 00000020: 6e69 7368 6564 0a nished.
>     >
>     > The stdout BOM was correctly removed but the stderr BOM is still 
> present.
>     >
>     > According to
>     >
>     
> http://www.gnu.org/software/emacs/manual/html_node/elisp/Output-from-Processes.html
>    
>     >
>     > there is now way to handle stderr separately. I made this workaround for
>     the
>     > Emacs fsharp-mode:
>     >
>     >
>     
> https://github.com/juergenhoetzel/fsharpbinding/commit/d0d3600c38d0e9f47a621583d0fc82685feda196
>    
>     >
>     > Are there any better solutions?
>     
>     You didn't tell what version of Emacs do you want this to be solved.
>     
> 
> GNU Emacs 24.5.1

Then I think you will have to remove the second BOM in your
application's Lisp code.  start-file-process redirects both standard
output and standard error to the same file descriptor, and Emacs reads
their mix from that file descriptor.  It will remove 1 BOM, but the
other will be left alone.

Alternatively, separate the standard output and standard error via
shell redirection, and then read one of them separately from a file.