Linux access

MATH do not have our own servers

MATH does not have servers dedicated to just faculty and students at MATH. We had at one point, but they were only seldomly used. So instead AUIT provides some general purpose Linux servers all students and faculty at AU kan use. See below.

Linux servers for general use

If you need to run simulation, a large calculation or something similar on a Linux server you can use the server

  • linuxapp.au.dk

This is actually several servers (see further explanation below). The server(s) are only accessible via SSH. To login you use your auAUID as your username and your normal AU password, that is

  • ssh -l auAUID linuxapp.au.dk

(other SSH option may also be relevant such as -X and -Y).

If you use Windows, we recommend using the free tool Moba Xterm which includes SSH and other tools needed to communication with a Linux server from Windows (Moba Xterm also include a simple file transfer tool). On Mac and Linux SSH is already available, though you will probably need to install XQuartz on your Mac if you want to open a graphical interface from the Linux server and display it on your Mac.

On LinuxApp you will find tool like MatLab, Mathematica, SAS, R, python, CPLEX etc. If it is free and available for Ubuntu, you can probably get the IT department to install it. Such request needs to be sent to the helpdesk

IMPORTANT

In order to avoid a lot of wasted space on AUs storage servers, most users does NOT have any storage space on LinuxApp to start with. You will need to ask the Helpdesk to grant you storage space for LinuxApp.

Here is how to spot if you do NOT have storage space on LinuxApp.

  1. Login to linuxapp.au.dk using SSH
  2. If login is successfull you will be greated by a welcome message
  3. If after after the message you are NOT greated by a command line prompt similar to auAUID@linuxapp01:~$, then you do not have storage access and the server have automatically logged you out.
  4. This ia also visibly if you scroll up to the start of the welcome message, at the very start you will find a message that the server cannot create files in /home/auAUID

How to get LinuxApp storage access

Contact your local Helpdesk (email is preferred, they will need to know your auAUID), explain to them that you want to use the LinuxApp server and that you do not seem to have a storage space available on it and that you would like to get such a storage space.

If the helpdesk does not know what LinuxApp is (as this is a Linux server the Windows supporters may never have heard of it), ask the helpdesk supporter to look up LinuxApp (or linuxapp) in their internal Support Wiki, which will tell them that in case a person need storage space for LinuxApp, the helpdesk need to register a task at GenApps (IT backoffice) for this person to have LinuxApp storage access.

About LinuxApp

Behind linuxapp.au.dk is actually several servers, linuxapp.au.dk is just a front end/load balancer. As os Jan-2020 it is 3 virtualised versions similar to Intel Xeon each with 64Gb of RAM. They are not super computers, but generally more capable than your average desktop PC or laptop.

Note that the servers does not have dedicated GPUs.

Other noteworthy things you need to know

  • Since linuxapp.au.dk is a frontend/load balancer, you have no control over which server you end up with. It will be one of linuxapp0, linuxapp02 or linuxapp03
  • Linuxapp01,-02,-03 are NOT accessible from the outside, thus you always have to access them through linuxapp.au.dk
  • Linuxapp0x share filsystems (as long as you place your files in your storage area, /home/auAUID), thus for file transfer it does not matter which server you land on.
  • Make sure to read the SSH Welcome Message when you log in, it contains several hints as to how one goes from say Linuxapp01 to Linuxapp03 or ask the servers which processes you have running on the three servers (in case you forgot which of the three servers your simulation is running on).

    Jump to another: ssh linuxapp0x
    See what processes you have running: ps -fu $USER
    Ask another server if you have something running on it: ssh linuxapp02 ps -fu $USER
  • If you are on Eduroam or want to use linuxapp.au.dk from home, you will need to use VPN (the general AU VPN "AU Access" is enough, thus all students can access LinuxApp via VPN), see au.dk/vpn for more information
  • One-way communocation: All communications with linuxapp.au.dk needs to start from your computer. You cannot  "put" a file from linuxapp.au.dk onto your computer, you need to "pull" it it from your computer instead.

A few things that are probably useful to look into as a new linux user

  • Learn to use the commandline (basic folder navigation, move/copy files, inline editing a file, I tend to use nano for simple exits)
  • If you need to run lengthy simulations/calculations (that does not run via a graphical interface) it is a good idea to learn to use tmux (terminal multiplexer). This is a sort of "remote desktop" for command lines. If you start your simulation inside tmux, then tmux enables you to leave the tmux session with the simulation still running inside it!! Logout of LinuxApp, then come back later (to the same Linux0x-server) and then resume the tmux session where the simulation is running. Without tmux you often need to stay logged in to LinuxApp for the duration of the simulation.
  • Learn to run MatLab, R or SAS simulations/calculations without using a graphical interface (say Rstudio), then you can easily use it with tmux (mentioned above) and can just start your simulation, log out can come back to it later.
  • A file transfer program like FileZilla can be useful for transferring files to and from LinuxApp.
  • Windows users are recommended to use Moba Xterm (its free).

Otherwise feel free to come and ask. Just remember that LinuxApp are NOT MATH servers they are maintained by AUIT (their Linux department)