[Bug 1297051] Re: gnome-terminal doesn't recognise C1 controls

[Egmont Koblinger]

> It's true that we could have defined the answerback response to have a
syntax that basically matches the response to \e[c ...

That's a crucial issue here.  If all terminals responded in a well-
defined syntax (i.e. <some_unique_prefix>terminalname<terminator>) then
I'd happily move ahead and hardcode "VTE" or even "VTE <versionnumber>".
But that's not the case, even putty defaults to emitting "PUTTY" which
you apparently had to change to "PUTTY^M" and it still has the problem
that you can't distinguish this from a string typed by the user, or
let's say if the user quickly pressed the letter 'x' you might
misbelieve that the terminal type is "xPUTTY" and so ugly heuristics
begin...  In other words, in order to make the answerback useful, the
answerback *has* to be configurable because of its broken design, and
sysadmins need to do a lot of configuration within a local system to get
something useful out of this.

In gnome-terminal (and generally in Gnome) the approach seems to be just
the bare minimum of absolutely necessary config options, and preferably
no hidden settings. Adding support for the answerback would require an
API between VTE and Gnome-terminal, and a preference setting that UI
folks probably wouldn't approve. We've already removed more important
and more popular options. This is why I don't think this feature will
ever be implemented.

Could you go with ^[[>c please, and treat version number of 4 digits
around 3600 or so as VTE?  Or create a trivial one-line patch for your
VTE?

> I could find no trace on the above-mentioned web site, or any other,
of \e[?40h being a valid command in a real terminal. I think it might be
an xterm invention.

VTE treats xterm as the primary reference.  If you want something to be
changed, you'd have to prove explicitly that xterm is doing it wrong.

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https://bugs.launchpad.net/bugs/1297051

Title:
  gnome-terminal doesn't recognise C1 controls

Status in “vte3” package in Ubuntu:
  New

Bug description:
  gnome-terminal seems not to recognise the C1 control characters.

  The particular character that is a problem for me is CSI. However
  there may be a generic issue with non-support of this whole range of
  characters.

  This range of characters should only be recognised when the encoding
  is a character set that is defined to include the C1 control
  characters but, at a quick look, that is all of the ISO-8859-x
  character sets and Unicode. (C1 control characters require encoding as
  a 2 byte sequence when the encoding is UTF-8. As unlikely as this may
  be to occur in practice, UTF-8 is not inconsistent with C1 control
  characters.)

  Part of the motivation for raising this bug report is that PuTTY seems
  to have declined in reliability recently and so I looked at why I am
  using PuTTY as opposed to gnome-terminal. Correct support of C1
  control characters is one reason. This works in PuTTY. It does not
  appear to work in gnome-terminal. Perhaps resources would be better
  spent making gnome-terminal work as well as PuTTY does, rather than
  attempting to get PuTTY fixed.

  ProblemType: Bug
  DistroRelease: Ubuntu 13.10
  Package: gnome-terminal 3.6.1-0ubuntu6
  ProcVersionSignature: Ubuntu 3.11.0-18.32-generic 3.11.10.4
  Uname: Linux 3.11.0-18-generic x86_64
  NonfreeKernelModules: nvidia
  ApportVersion: 2.12.5-0ubuntu2.2
  Architecture: amd64
  Date: Tue Mar 25 11:08:00 2014
  InstallationDate: Installed on 2011-10-25 (881 days ago)
  InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
  MarkForUpload: True
  SourcePackage: gnome-terminal
  UpgradeStatus: Upgraded to saucy on 2013-11-08 (136 days ago)

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