X11 on NeSI
Prerequisite
- Have working terminal set up.
X-11 is a protocol for rendering graphical user interfaces (GUIs) that can be sent along an SSH tunnel. If you plan on using a GUI on a NeSI cluster you will need to have an X-Server and X-Forwarding set up.
X-Servers¶
You must have a X-server running on your local machine in order for a GUI to be rendered.
Download links for X-servers can be found below.
| Operating System | Download |
|---|---|
| MacOS | Xquartz |
| Linux | Xorg |
| Windows | Xming |
Make sure you have launched the server and it is running in the
background, look for this 
symbol in your taskbar.
Note
MobaXterm has a build in X server, no setup required. By default the
server is started alongside MobaXterm. You can check it's status in
the top left hand corner
(
=on, 
=off).
X-Forwarding¶
Finally your ssh tunnel must be set up to 'forward' along X-11 connections.
OpenSSH (terminal)¶
Make sure the -Y or -X flag is included
ssh -Y user@lander.nesi.org.nz
ssh -Y login.nesi.org.nz
MobaXterm¶
Under 'session settings' for your connection make sure the X-11 forwarding box is checked.
If the 
button in
the top right corner of your window is coloured, the X-server should be
running.
X-Forwarding with tmux¶
In order to connect X11 into a tmux session you make the following change to your config file.
tmux show -g | sed 's/DISPLAY //' > ~/.tmux.conf
Interactive Slurm jobs¶
In order to make use of X11 in an interactive Slurm job:
srun¶
Add the flag --x11
srun --ntasks 36 --mem-per-cpu 1500 --time 01:00:00 --x11 --pty bash
salloc¶
add the flag -Y when ssh-ing to the node.
ssh -Y wbn001
XVFB¶
If your application requires X11 in order to run, but does not need to
be interactive you can use X11 Virtual Frame Buffer. This may be
required to in order to run visual applications on the compute nodes.
Prepending any command with xfvb-run will provide a dummy X11 server
for the application to render to.
e.g.
xvfb-run xterm