Subject: Re: bug#21571: [patches] some small message improvements

From: Benno Schulenberg <[email-masked]>
Date: Mon, 28 Sep 2015 13:07:16 +0200

On Sun, Sep 27, 2015, at 20:14, Andreas Schwab wrote:
> Benno Schulenberg <[email-masked]> writes:
> > Or does it just mean that when ONLRET is set that the receiving
> > end will do also a CR when a LF is received?  The tty doesn't do
> > any conversion, it just has to be aware that sending a LF causes
> > also a CR in order to be able to line things up properly?
> 
> Yes.

Hm.  But the termios layer cannot know whether the sender is
aware that NL also causes a carriage return, so it cannot take
any compensatory action on the data coming through.  So, ONLRET
by itself does not do anything at all.  Only when combined with
ONOCR does it have an effect: not only after a CR but also after
an NL any subsequent CRs are discarded, until some printable
character moves the cursor out of column zero again.  Right?

Maybe then the documentation should mention that ONLRET
is only useful in combination with ONOCR?  Because otherwise
the introduction of the "Output settings" section is somewhat
misleading: "These settings control operations on data sent to
the terminal."  As ONLRET does not cause anything to be done
with the data unless ONOCR is set.

Glibc only documents ONLCR, not OCRNL nor ONLRET nor ONOCR.
Is that just a lack of documentation?  Or does it mean that
the latter three flags are in effect nonfunctional?

Benno

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