General tips#
GUI applications on clusters#
Even though calculators are accessed via a text-based SSH connection, you can usually open applications that have a
graphical user interface (GUI) and which are installed on the calculator (for example: ncview
). In this case, the
application is run remotely on the calculator but the GUI window(s) are opened locally on your own computer. This is
done through a process called X-forwarding. To use it, you must have an X-server installed on your own computer. If
your computer is a GNU/Linux system, it should be installed by default. On MacOS, the recommended X-server is XQuartz,
which you can install either by downloading the package file from the official XQuartz
webpage or by using brew:
brew install --cask xquartz
Once an X-server is available on your system, use the -X
option to activate X-forwarding when connecting to the
calculator:
ssh -X username@calculator.address
You can now launch GUI applications from the calculator.
Caution
For security reasons, -X
is prefered over -Y
to activate X-forwarding when connecting to a remote host (man ssh
for more information).
If you use X-forwarding, you might observe that it stops working after some time, even though the SSH session still
works. This is because most SSH servers are configured by default to drop X-forwarding after some time has passed. You
can deactivate this timeout in the ~/.ssh/config
file on the client side (ie. on your own computer):
Host *
ForwardX11Timeout 0