tcl/tk question

[hag-MhwEwdFzMDlg9hUCZPvPmw at public.gmane.org (Daniel Hagerty)]

Jerry Feldman <gaf-mNDKBlG2WHs at public.gmane.org> writes:

> tcl/tk script. All well and good. The one question I have is how can I
> detect in a script that an X server is running. Most people use putty
> from their Windows laptops, and I want the script to run in text mode if
> they have not run ssh -X (or if Exceed is not running). One method would
> be to check the $DISPLAY. But if they use Putty, the -X option would be
> set. If I run wish(1) it returns 0, but does print out a line of text,
> "Application initialization failed: " that I could check and switch to
> text mode. I'm looking for a better way of testing.

    As far as the usual X architecture is concerned, you don't.  You
set DISPLAY to indicate X support.  If you don't have X support, you
communicate this to apps by not setting DISPLAY.

    If your users insist on doing the wrong thing, your approach will
probably work.  Other routes include using a cheap X query tool, like
xdpyinfo, xrdb, xlsclients, etc.

    If I had problems with users miscommunicating X support to apps
like this, I'd try to handle it in the login environment, rather than
in a particular app.  Your app probably isn't alone in doing the wrong
thing with a bogus DISPLAY.