Steffen Nurpmeso <stef...@sdaoden.eu> wrote, on 26 Jun 2020:
>
> Andrew Josey wrote in
> <660b59c1-98a7-490b-b6dc-391fb7ec5...@opengroup.org>:
> |I'm pleased to announce the availability of the first draft of the \
> |202x revision of the standard.
> |This draft is the first committee draft.
>
> ..But related to that as well as to the current version.
> I searched for mailx and encountered two instances of
>
> This sequence, which demonstrates redirecting standard error to
> a pipe, is useful in a command procedure (the sequence of output
> redirection specifications is significant):
>
> diff file1 file2 2>&1 >outfile | mailx mygroup
>
> which effectively sends an empty message to the alias "mygroup".
> And i wonder whether this really was the intention.
As per the introductory text, it is demonstrating the use of:
... 2>&1 >outfile | ...
to redirect stderr to a pipe (with stdout not going to the pipe).
The message is only empty if diff does not report an error.
> I would, in the context of the example(s), understand
>
> diff file1 file2 2>&1 >outfile |
> mailx -s "File difference available" mygroup
Yes, although the subject line would be misleading if diff reported
an error.
> This is all rather confusing however. Maybe
>
> diff file1 file2 2>&1 |
> mailx -s "File difference of file1 and file2" mygroup
>
> was meant. Or
>
> diff file1 file2 2>&1 | tee outfile |
> mailx -s "File difference of file1 and file2" mygroup
>
> or
>
> diff file1 file2 2>&1 > outfile;
> mailx -s "File difference of file1 and file2" mygroup < outfile
None of those demonstrate sending stderr to a pipe with stdout not
going to the pipe. The text doesn't state the stdout-not-to-pipe
part, but it emphasises the sequencing of the redirections so that's
clearly the point of it.
> Shall this end up as a doc enhancement request?
Since the text hasn't changed in Issue 8 draft 1, if you raise a
Mantis issue it should be for the current standard (i.e. choose the
Issue7+TC2 project).
--
Geoff Clare <g.cl...@opengroup.org>
The Open Group, Apex Plaza, Forbury Road, Reading, RG1 1AX, England
