change in tcsh behavior

matthew at matthew at
Tue Jul 28 13:25:03 UTC 2020

On 28/07/2020 12:55, Robert Huff wrote:
> From: Robert Huff <roberthuff at>
> To: Mateusz Piotrowski <0mp at>
> Subject: Re: change in tcsh behavior
> In-Reply-To: <bdd8326c-ce1a-2eb3-27f7-57e30b10597d at>
> References: <24351.11091.522286.251422 at>
> 	<e48b4a3e-9861-71ba-1130-9e5de911e629 at>
> 	<24351.24025.555285.682585 at>
> 	<bdd8326c-ce1a-2eb3-27f7-57e30b10597d at>
> X-Mailer: VM 8.2.0b under 26.3 (amd64-portbld-freebsd13.0)
> --text follows this line--
> Hello:
>>   >   > 	How do I go back to the old output?
>>   >
>>   >   Set sysctl kern.tty_info_kstacks to 0.
>>   > 	Umm ... is there a reason this isn't the default?
>>   I think the idea was that it is useful enough to enable it by
>>   default. Otherwise, it would be really hard to discover it. This
>>   change was well received by various developers, and it also had an
>>   revision where the default was changed from 1 to 2 (or something)
>>   to make it a little bit more compact.
> 	And if it makes their life easier, then I approve.
> 	However:
> 	1) something visibly changed, that
> 	2) affects the default system shell and therefore a _lot_ of
> 		users, many of which like the old way
> 	3) without warning or documentation (e.g. a single line entry in
> 		src/UPDATING), and figuring out what happened is, in your
> 		words "really hard to discover" for the casual user.

The OP is running 13-CURRENT.  That's the bleeding edge, development 
version.  New stuff appears in CURRENT all the time, possibly with 
little more notice than a review on Phabricator or a short e-mail 
exchange.  Some of what appears is initially buggy.  Some is 
experimental and ultimately ends up completely different.  As someone 
who has chosen to use the development version, you are expected to be 
able to cope.

If you aren't prepared to deal with that, then choose one of the release 
versions.  These come with all sorts of niceties, like release notes, 
guarantees of ABI stability, no untested code and no massive re-engineering.

The `kern.tty_info_kstacks` sysctl will appear in the next stable 
release branch due out later this year.  IIRC it will be present but 
default to '0' thus preserving existing behaviour.  (I could be wrong 
about that.  I'm trying to recall a conversation on Slack from several 
weeks ago.)  In any case, there will be an item in the release notes and 
all of the usual sorts of documentation.



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