Re: Determine if x is running

Rick Stevens <ricks@xxxxxxxx> · Tue, 10 Feb 2009 10:30:55 -0800

Karl Pearson wrote:

On Mon, February 9, 2009 3:25 pm, Ray Van Dolson wrote:

On Mon, Feb 09, 2009 at 02:21:24PM -0800, redhat@xxxxxxxxxxxxxx wrote:

I'm am writing a script that sets some various security settings on
Redhat Boxes.  I would like to try to determine if a gui may be
running
on the box the script is run on.  If so, I would echo some additional
text to stdout that instructs the user that they may required to
manually perform some additional settings manually.  Things having to
do
with screen savers.  Anyway, I thought about the following:

1. use the runlevel command or who -r to see if the system is in
runlevel 5.  This seems flawed since the box may have been started in
runlevel 3 and the startx command may have been used. The commands
would
show runlevel 3.
2. Check if the environment variable DISPLAY is set.  If so, seems
like
there is a good chance that they are running a gui. (maybe)

DISPLAY is set by the user's login process, so it would be empty for a
cron job.

Is there a better way to check this that anyone can think of?

Would it be sufficient for your needs to check is the X process is
running?

Theoretically, there is probably some way to interact with a running X
server directly from a script (even if you're not in control of its
terminal) to determine if it's running.

The easiest way is a small shell script:

	#!/bin/bash
	RES=`ps ax | grep -v grep | grep -i xorg`
	if [ $? -eq 0 ]; then
		echo X is running
	else
		echo X is NOT running
	fi

(substitute the name of your X server for "xorg" if you're not running
XOrg).  On top of that, $RES will be empty if X isn't running, and will
contain the line from "ps ax" describing it if X is running.

This should work regardless of if the machine starts X by going into run
level 5 and firing up a greeter or startx from some other run level.  It
looks for the instance of the X server itself.

Also, X typically listens on port 6000 locally.

Not unless you TELL it to.  It will listen on local Unix domain ports, 

but not TCP/IP.

Just run runlevel and it will return what runlevel is currently being
run in the second response, i.e: on boot, it will show N 5 or N 3 for X
or text depending on what's in /etc/inittab on the initdefault line.

Now then, that doesn't handle startx, but how many times might that
actually happen. On my servers, there's no CRT/LCD, so no user will be
running startx. They might run vncserver, however, and use an X display
remotely. But, they better not leave it in that state, else that will be
disabled for them. All the users in my network have Linux PCs anyway,
and have no reason to be on the server unless they are editing a web
page, but then they can use fish:// in Konqueror or sftp:/// in
Nautilus.

I suspect I've confused more than helped, but ask away and someone
smarter than me will respond.

The shell snippet I provided
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- Rick Stevens, Systems Engineer                      ricks@xxxxxxxx -
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