Multiple instances of X using startx command

rutgerw · 07-29-2006, 03:27 PM

I know it's possible to start a second instance of X using the command

Code:

startx -- :1

. I wonder however if it could also be possible to start a second instance of X without the additional options, e.g. startx searches for the next available display. So if two users are logged in at the same time and both want to use X they do not need to hassle with the commands.

thnx

Brian1 · 07-29-2006, 03:56 PM

I am not sure where to start but this is a thought. A script that checks to see if display :0 exist. If so then it uses the staxtx :1. Just not sure how to check to see if display :0 or so is active. This might give you a start or someone might continue on with this idea.

If I get some spare time I might look into it further.
Brian1

raskin · 07-29-2006, 03:57 PM

Try writing a wrapping script to find a free display:

NUM=$( ps auxwww | grep '\<X\>' | grep -v grep | sed -e 's/.* :$[0-9.]\+$$ .*$*/\1/' | sort -n | tail -1 | (read; echo $REPLY + 1 | bc ); );
startx :$NUM

If you really want to understand it all, read man bash, man sed, man grep, man tail, man sort. And know that bc is a calculator..

Or ask concrete questions

pixellany · 07-29-2006, 04:54 PM

Quote:

Originally Posted by raskin

Try writing a wrapping script to find a free display:

NUM=$( ps auxwww | grep '\<X\>' | grep -v grep | sed -e 's/.* :$[0-9.]\+$$ .*$*/\1/' | sort -n | tail -1 | (read; echo $REPLY + 1 | bc ); );
startx :$NUM

If you really want to understand it all, read man bash, man sed, man grep, man tail, man sort. And know that bc is a calculator..

Or ask concrete questions

Just for kicks, I am trying this one piece at a time.
I gather that you are looking for all lines with "<X>" in them. On my machine (3 X-servers running) there are no such lines...

ps auxwww | grep '\<X\>' returns only one line:
mherring 8405 0.0 0.0 3912 660 pts/1 R+ 14:49 0:00 grep \<X\>

obviously this is what your script wants to delete (using grep -v grep)---then there would be nothing.

So maybe the syntax <X> is not always used??

raskin · 07-29-2006, 05:11 PM

What grep do you have? I have (grep --version) 2.5.1 . If you have other version - replace \< by just < and \> by > . This means end-of-word in regexp.

rutgerw · 07-30-2006, 04:56 AM

Perhaps I could be a bit more concrete. If you edit for example your kdmrc file (when using kde of course) it is possible to have several 'reserve' Xservers. So when :0 is taken and you want to start up a new session the new session will be on :1. I would like to have the same behavior when starting X from the command line using the startx command. Does anyone know a config file I need to edit for this behavior?

regards

pixellany · 07-30-2006, 09:01 AM

Quote:

Originally Posted by raskin

What grep do you have? I have (grep --version) 2.5.1 . If you have other version - replace \< by just < and \> by > . This means end-of-word in regexp.

I also have 2.5.1---Now I realize what /< and /> are supposed to be doing: You are looking for "X" by itself--right?
When I do ps auxwww, this does not occur.

I have a hunch that these are the lines you are trying to find:

Code:

root      2477  2.6  1.7  23916 17716 tty7     Ss+  Jul29  21:13 /usr/bin/Xorg :0 -audit 0 -auth /var/gdm/:0.Xauth -nolisten tcp vt7
root      2524  0.0  0.4  10756  5104 tty9     Ss+  Jul29   0:01 /usr/bin/Xorg :1 -audit 0 -auth /var/gdm/:1.Xauth -nolisten tcp vt9
root      2548  1.3  1.8  25696 18872 tty10    Ss+  Jul29  10:52 /usr/bin/Xorg :2 -audit 0 -auth /var/gdm/:2.Xauth -nolisten tcp vt10

Brian1 · 07-30-2006, 10:52 AM

No config file I know of. The above help from others for finding a running X server display is a start. Once one determines whether :0 is active, then ones will start :1. What one would do is create a script called lets say startxx. It will run a check (like using the above command like others above have provided) to see if :0 is active if it is it will then check for :1 and so on. Now if :1 is not active then it will issue the command startx :1 like you want. I am not great at scripts but maybe again others can help or study up on simple scripting and write your own. If I get time again I may work on this.

Brian1

raskin · 07-30-2006, 11:28 AM

Oops. Pixellany, in your case I would just substitute Xorg for X and have no problems. Just your distro makes this other way than my scripts in LFS system..

Brian1 · 07-30-2006, 03:58 PM

Got time to look this over and review the above post and command there Raskin. Looks good and works here. I can issue the command and then do a echo $NUM and shows what $NUM will be. Started a second display and run the command and it showed the value to be 2 since display 0 and 1 were active.

Code:

NUM=$( ps auxwww | grep '\<X\>' | grep -v grep | sed -e 's/.* :\([0-9.]\+\)\( .*\)*/\1/' | sort -n | tail -1 | (read; echo $REPLY + 1 | bc ); );  echo $NUM

Simply from here on out. Thanks for the info.

Brian1