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Accessing the Powerwall via SSH

 

Using SSH

To connect remotely to a boba machine, use ssh. eg:

 ssh boba142.sinrg
or
 ssh boba142.sinrg.cs.utk.edu
Adding "-XY" to the ssh command will cause the X windows to display on your local terminal, which is necessary when using x2x, DMX, Vizard, and the GUI Toolkit.

Setting environment variables:

When you ssh to a boba machine, you will be assigned a $DISPLAY environment variable. This variable allows you to run graphical X11 applications on the remote machine that display back on your desktop. The $DISPLAY variable might look like localhost:10.0, for example, where the 10.0 increases by one for every new remote connection. To make applications display locally on the boba machine, simply set DISPLAY to ":0"

For csh:

 setenv DISPLAY :0
For bash:
 export DISPLAY=:0
To save your localhost $DISPLAY variable for later, first set LOCALDISPLAY to $DISPLAY (csh):
 setenv LOCALDISPLAY $DISPLAY
Note: It is recommended to add this command to your .cshrc file, or the corresponding file for your shell.

Getting X authority to open a display

If you get the following error:

could not open display: :0
then X isn't allowing you to open a display.
To solve this problem, run the vidwal script which is located at:
/usr/local/bin/vidwal
You should now be able to run your X programs on that machine. If you login to a different machine and wish to run an X program on that machine, you must run the script again.
This script is only available on Powerwall-connected machines.

To be able to control the program running on the remote computer with your local keyboard and mouse, see x2x.

Example:
Show a program on a single powerwall screen and control it with your mouse and keyboard:

Step 1 ssh directly into the machine driving the screen you wish to use with -XY (example: boba122)
 ssh -XY boba122.sinrg
Step 2 change your environment variables:
 setenv LOCALDISPLAY $DISPLAY
setenv DISPLAY :0
Step 3 start x2x (see setup instructions here)
 x2x -from $LOCALDISPLAY -to $DISPLAY -geometry 400x400 &
Step 4 run your application