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From: mouse@larry.mcrcim.mcgill.EDU
Newsgroups: comp.windows.x
Subject: Re: UNIX/X-windows questions
Message-ID: <9101241238.AA17111@Larry.McRCIM.McGill.EDU>
Date: 24 Jan 91 12:38:51 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 23

>>> Is there a call to see if we are in X?
>> if (!strcmp("xterm",getenv("TERM")))

Or mterm, or aixterm, or sun, or any of the many other possible values
of $TERM when running under X....

> The best way is to try to open the display XOpenDisplay(":0.0").

Except that you may be in X, but the server may not be on the machine
you're trying to run the program on.

I would say that if -display is on the command line, use it.  Otherwise
check for DISPLAY in the environment, and if set, use it; otherwise,
assume X is not available.

This also allows the user to avoid using X even when available, by
unsetting DISPLAY in the environment.  (Yes, this is sometimes
desirable.)

					der Mouse

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