How do I make one X server display everything the same as another X server?

April 9, 2009 6:42 PM

How do I make one X server display everything the same as another X server?

I have an X server with two screens, say foo:0.0 and foo:0.1. I have another X server with two screens, say bar:0.0 and bar:0.1.

I want screen bar:0.0 to display everything on screen foo:0.1. In other words, if anything is sent to foo:0.1, it should also be sent to bar:0.0. I'd prefer not to change either X configuration.

Is this possible? If so, what's the best way to do this?

posted by mathlete to computers & internet (5 answers total)

Tell us about how you want to interact with them. Is one a dumb copy?

My best ideas are "xdmx" (maybe?) and/or "vino" + "xvncclient".
posted by cmiller at 7:10 PM on April 9, 2009

What kind of applications will you be running? One option is to have foo:0.1 export its framebuffer using a VNC server (e.g. vino, which comes with GNOME) and run a VNC client on bar:0.0. This won't be efficient enough for, say, full-screen video, but on a LAN the performance should be acceptable for more mundane stuff like web browsing and administration. There are some X server extensions that would need to be enabled on foo for the server to be able to monitor for updates to the screen, but I think they're turned on by default on modern Linux distributions.

(In other words, what cmiller said.)
posted by teraflop at 7:22 PM on April 9, 2009

x11vnc is an alternative to vino if you don't run Gnome.
posted by zsazsa at 7:50 PM on April 9, 2009

I've been looking at xpra which dubs itself as "screen for X" (also like xmove). Probably it does not allow simultaneous viewers attaching (I don't really get how that would work), but because gnu screen does allow multiple clients to attach to a terminal I thought of this program.

Hope it's interesting even if it doesn't help :)
posted by lordjoe at 9:52 PM on April 9, 2009

No, one should not be a dumb copy.

The applications will be applications, such as OpenOffice or a web browser. Video through the web browser, like on YouTube, should work -- maybe not full screen though.

What if foo:0.1 didn't actually exist but I wanted bar:0.0 to look like foo:0.1? That is, if I set DISPLAY=foo:0.1, the application would show up on bar:0.0. What would my choices be then?
posted by mathlete at 11:26 PM on April 9, 2009