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From: net@tub.UUCP
Newsgroups: comp.unix.questions
Subject: Re: "screen" vs. "wm" - (nf)
Message-ID: <50000002@tub.UUCP>
Date: Fri, 28-Aug-87 13:54:00 EDT
Article-I.D.: tub.50000002
Posted: Fri Aug 28 13:54:00 1987
Date-Received: Tue, 1-Sep-87 04:06:33 EDT
References: <16048@teknowle.UUCP>
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Nf-ID: #R:teknowle:16048:tub:50000002:000:2332
Nf-From: tub!net    Aug 28 18:54:00 1987

> I'd appreciate any comments from anyone who has used both the "screen"
> program recently posted to comp.sources.whatever and the "wm" program
> of an earlier vintage, comparing/contrasting the two.

I use neither "screen" nor "wm", but as the author of "screen" I think I'm
in a position to comment on this.

Both window managers manage a set of virtual UNIX terminals that have a set
of processes connected to it (usually -- but not necessarily -- interactive
login shells) and map this set to a single real (or virtual) terminal.
While window managers like "wm" split the screen into multiple windows
(vertically), "screen" manages a set of independent equally-sized "logical
screens".

In contrast to "wm", where all windows are visible at each point of time,
"screen" always displays exactly one logical screen.  You can switch to a
different screen by means of a sequence of control characters; for
instance, Ctl-A Ctl-A activates the screen that has been displayed
previously.

Processes connected to a logical screen that is currently not displayed do
not get blocked or stopped.  You can arrange that each time a bell is
output to a background screen, a notification is displayed in the status
line of the currently displayed screen; this can be used to indicate that a
"make" or something has terminated in a currently not visible screen and to
draw one's attention to a background screen when someone directed a talk(1)
or write(1) to that screen.

I personally don't think that it makes much sense to divide an ordinary
24x80 screen into even smaller areas.  If you *do* need this functionality
together with the function offered by "screen", you can run a "wm"-like
window manager (or an Emacs) under "screen" (you can even have a separate
window manager in each logical screen, if you like).

Another big problem with "wm"-like window managers is that they require a
terminal with scrolling regions or insert/delete line, otherwise the only
way for a window to scroll it's contents up is to redraw the entire window.
Even with the aid of scrolling regions or insert/delete line, displaying a
long text (e.g. "cat /etc/termcap") is unacceptably slow (at least with the
window managers I have seen so far).

--
    Oliver Laumann, Technical University of Berlin, Germany.
    ...!pyramid!tub!net   or   net@TUB.BITNET