Suspending emacs on character terminals and "screen switching"

Suspending emacs on character terminals and "screen switching"

[Casper Gripenberg]

Does anyone know what the terminal capability is that
makes emacs switch back to the "shell screen" when you
suspend emacs?

I made a gif animation showing what I mean:
http://zoidberg.homeip.net/schtuff/EmacsSuspendSwitch.gif

I run emacs on two computers. One is OpenBSD and the
other FreeBSD. Emacs works fine on both but on FreeBSD
I can't get it to "switch screens" when I suspend it.
No matter what terminal type I set.

The screen switching is really useful when having to
suspend emacs and go back to the command line to see
what your program output was, or part of a manpage or
whatever.

Why can't I get it to work on FreeBSD? What terminal
capability or setting is missing over there? I'm sure
I could tweak a termcap file or something and get it
going, but I can't figure out what it is emacs is
looking for to activate this switching feature.

Look in the video. Setting term to xterm activates
the behaviour, setting it to vt100 disables it.

Anyone got any ideas how to get emacs to do this
on my FreeBSD box too?

Casper

Re: Suspending emacs on character terminals and "screen switching"

[Maciej Katafiasz]

Den Sat, 05 May 2007 02:25:08 +0300 skrev Casper Gripenberg:

> Why can't I get it to work on FreeBSD? What terminal
> capability or setting is missing over there? I'm sure
> I could tweak a termcap file or something and get it
> going, but I can't figure out what it is emacs is
> looking for to activate this switching feature.

It seems to be smcup / rmcup, nrrmc also influences that, according to the
manpage.

Cheers,
Maciej

Re: Suspending emacs on character terminals and "screen switching"

[Romain Francoise]

Casper Gripenberg <casper.gripenberg@kotiportti.fi> writes:

> Does anyone know what the terminal capability is that makes emacs
> switch back to the "shell screen" when you suspend emacs?

What you're seeing is called the "alternate screen", when TERM=xterm
Emacs draws its frame in the alternate screen, leaving the original
screen alone.  When TERM=vt100 then Emacs uses the original screen
buffer, which (as you've noticed) makes scrollback invisible.  The
corresponding termcap entries are 'ti' and 'te'.

A Google search for "xterm alternate screen" should return plenty of
relevant results.

Re: Suspending emacs on character terminals and "screen switching"

[Tyler Smith]

On 2007-05-04, Casper Gripenberg <casper.gripenberg@kotiportti.fi> wrote:
>
> The screen switching is really useful when having to
> suspend emacs and go back to the command line to see
> what your program output was, or part of a manpage or
> whatever.
>

You can read manpages from within Emacs using M-x man, or run a
separate shell in an Emacs buffer for testing programs with M-x
shell. I know that doesn't help solve your problem, but it could limit
how often you actually need to switch back to the command line.

Cheers,

Tyler