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comp.windows.x Frequently Asked Questions (FAQ) 7/7
Section - 169) How can my application tell if it is being run under X?

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Top Document: comp.windows.x Frequently Asked Questions (FAQ) 7/7
Previous Document: 168) Why do I get a BadMatch error when calling XGetImage?
Next Document: 170) How do I make a "busy cursor" while my application is computing?
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A number of programs offer X modes but otherwise run in a straight
character-only mode. The easiest way for an application to determine that it
is running on an X display is to attempt to open a connection to the X
server:
	
	display = XOpenDisplay(display_name);
	if (display)
		{ do X stuff }
	else
		{ do curses or something else }

where display_name is either the string specified on the command-line
following -display, by convention, or otherwise is (char*)NULL [in which case
XOpenDisplay uses the value of $DISPLAY, if set].

This is superior to simply checking for the existence a -display command-line 
argument or checking for $DISPLAY set in the environment, neither of which is 
adequate. [5/91]

Note that there is a lengthy delay if $DISPLAY exists but is set to a machine
which is not currently running an X server.

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Top Document: comp.windows.x Frequently Asked Questions (FAQ) 7/7
Previous Document: 168) Why do I get a BadMatch error when calling XGetImage?
Next Document: 170) How do I make a "busy cursor" while my application is computing?

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Last Update March 27 2014 @ 02:12 PM