• Systems Development for Computational Science [CS107, AC207] - Fall 2023
  • Lecture hours
  • Grade deadlines
  • Pair Programming
    • Example 1 (simple)
    • Example 2 (launch session with specific application)

Systems Development for Computational Science [CS107, AC207] - Fall 2023

This repository is private for the CS107/AC207 teaching staff only.

Lecture hours

Day	Time
Tuesday	2:15 - 3:30 PM
Thursday	2:15 - 3:30 PM

Grade deadlines

• Exam/presentation: TBD
• Grades: TBD

Pair Programming

We will continue the pair-programming practice as of the class last year. We will not use deepnote as it is too limited to an IDE interface only. We will use tmate instead which is based on the tmux terminal multiplexer. It allows for easy sharing of a command line session or a specific instance of a program in read/write and read-only modes via ssh or web browsers.

There is no X11-forwarding in tmate which means that we will be having some fun in the command line. Text file editing will be performed in any text editor that supports a text-based user interface (TUI). Examples are vim, emacs, nano.

Please get familiar with tmate and possibly some basics for one of the text editors mentioned above.

Students who use a Windows OS need to install the Linux subsystem. On Ubuntu they can do

sudo apt-get install tmate

If that fails or the chosen Linux system does not support tmate in their repository, pre-compiled binaries can be downloaded from the tmate release page here.

Example 1 (simple)

The easiest way to start a new tmate session is simply to execute

tmate

This will drop you in a tmux session running an instance of bash. You will see a short notification on the bottom with the ssh command that must be issued to connect to the session just started (the computer you ran tmate will be the host machine, everybody else you share links with will connect to that machine). The ssh command shown at the bottom is for read/write access, only share this link with people you trust. Anybody with this link can access your currently running bash instance and could do harm to your system. NEVER run tmate with root and be careful with password-less sudo (general advice: avoid password-less sudo).

You can see all available session links by running

tmate show-messages

inside the running session. The output looks similar to this (links will be different for every session):

Fri Aug  6 17:59:32 2021 [tmate] Connecting to ssh.tmate.io...
Fri Aug  6 17:59:32 2021 [tmate] Note: clear your terminal before sharing readonly access
Fri Aug  6 17:59:32 2021 [tmate] web session read only: https://tmate.io/t/ro-XfxM6pNhwEeU5HmLSWdFedEmH
Fri Aug  6 17:59:32 2021 [tmate] ssh session read only: ssh [email protected]
Fri Aug  6 17:59:32 2021 [tmate] web session: https://tmate.io/t/44su2fJmytVfbt8XSrcpg5U5X
Fri Aug  6 17:59:32 2021 [tmate] ssh session: ssh [email protected]

There are read-only links and read/write links for ssh sessions or you could also use your web browser to access a session. In order to use ssh you need to setup an ssh key if you have not done so already. If you do not have such a key, you may create one by running

ssh-keygen -t rsa -b 4096

If it is impossible for a student to get tmate running, he/she can always pair with a student that has managed to set it up correctly and join the session via the web browser.

tmate is perfect for any coding related communication. For example, debugging, work on the project and of course pair programming. There is no audio channel integrated in tmate. If students are remote, a zoom session or similar must also be established for oral communication.

If you are not dropped into a shell after you execute tmate it may be because you are using a shell different than zsh. Install zsh on your system using your package manager and run tmate like this

SHELL=/bin/zsh tmate

Example 2 (launch session with specific application)

You can launch a specific application with tmate and limit the interaction to this application, for example the vim text editor. This is useful for pair-programming but the approach in Example 1 would work just as well (note that in vim, for example, one could start a shell and get access to the command line too).

To launch tmate with a specific application run this command (e.g. with vim)

tmate -F new-session vim [optional filename to edit]

The following figure shows an example session with 3 clients connected (two ssh and one in the web browser read-only)

These clients are all on the same machine but in general, students will use their own laptops. The window on the lower right shows the output of the running tmate session and is only visible on the machine where the session has been launched. Killing this process with Ctrl-C will immediately terminate the session on all connected clients. Note that tmux (or tmate) rescales to the smallest screen resolution of all participating clients. Ideally all clients want to maximize their screen.