[ale] How to tell if X is up?

[linuxhat at mailandnews.com]

On 23 Jul 1999, hirsch at mathcs.emory.edu wrote:

>Dan Newcombe <Newcombe at mordor.clayton.edu> wrote:
>> On Wed, 21 Jul 1999 linuxhat at mailandnews.com wrote:
>> > On 21 Jul 1999, Dave Brooks wrote:
>
>> > Should have been more clear.  *from within a C program*, how can we tell
>> > if  X is up and accepting connections on the local machine?  (also, from
>> > within a script, the above would have to be just a little bit smarter....)
>> 
>
>> #include <X11/Xlib.h>
>> #include <stdio.h>
>> int main(int argc,char *argv)
>> {
>>   Display *display;
>>   display=XOpenDisplay(NULL);
>>   if(display==(Display *) NULL) {
>>                 printf("Server not accepting connections\n");
>>           return(1);
>>   }
>>   return(0);
>> }
>> 
>> This works for me.  If I set my DISPLAY variable to a valid X server
>> accepting connections, then it works.  If I set it to a machine without an
>> X server (ie. NT :) then it prints the string.
>
>In the question he asks about the "local X server".  If your display variable
>points to a remote server this code will test that server.  It is not clear to
>me whether this is the desired behavior.  

Close enough for government work.  If we made sure "xhost + localhost" was
in the X initialization scripts and ran XOpenDisplay("localhost") we got 
close enough to the desired behavior to be useful.  Thanks, guys.

-- Glenn