CSCI 159 Lab exercise 1, tips and tools

CSCI 159 Lab exercise 1: tips and tools

There are a number of technical details that are likely to help when working on your labs this term, here we'll introduce a few of them.

Connecting to our CSCI servers from a laptop/desktop

You can use your own machine's browser of course, so we just need a way that you run issue linux commands on our server but from your machine.

Each of the three major platforms provides a way to open command windows on your own machine and then connect those windows to our server using a program called ssh. The three sections below describe how to do that.

If you're on Windows 10 or 11:
Open Windows PowerShell: open the programs menu either by right-clicking the Windows icon or using the Windows Key + X shortcut. Scroll through until you find PowerShell.
If you're on a Mac:
Go to Applications->Utilities->Terminal
If you're on your own Linux box:
Open a terminal window as we do in the labs (where it lies in your menus will depend on which flavour of Linux you're running).

Once you've opened a terminal window or powershell using the above, enter the following command in it:
ssh -l youruserid csci.viu.ca

The -l is a lowercase L, not a one, and be sure to use the userid you were given for your csci linux account.
The first time you connect it will probably ask if you trust this machine (if you want to connect and do work on it you pretty much have to).
It'll then ask for your password, type it and hit enter (it likely won't show anything happening as you type).

Once it finished connecting you'll be in your usual starting location in your linux account, and you can enter linux commands exactly as you would in the lab except: it won't allow you to use graphical tools like gedit that pop open new windows on the screen.

This means that for editing you'll have to use a text editor that works within the terminal window, common options are pico, vim, and emacs, e.g. pico somefilename or vim somefilename or emacs somefilename, without an & at the end.
Pico is the simplest but least powerful, it lists command shortcuts at the bottom of the window such as ^x (meaning control-X) to exit, ^o to save (writeout), etc.

move around, edit, compile, do test runs, and make submit as needed
when you're finished, type the command logout to disconnect from our server.

Jumping to other CSCI servers

Having everyone in CSCI 159 log into csci.viu.ca and work there causes a significant bottleneck: everyone is sharing the same machine, so gets reduced performance. Thus we want everyone to connect through csci.viu.ca, but then jump from there to another machine to distribute the load.

(The server's full name is otter.csci.viu.ca, generally referred to as otter.)

We have 18 other servers you can move to from otter, named pup1 through pup18, e.g. pup1.csci.viu.ca, pup2.csci.viu.ca, etc.

From otter you can jump to a pup using ssh, e.g.
ssh pup14

I strongly recommend that each time you ssh to csci.viu.ca you immediately ssh to a random choice of one of the pups. This spreads our students across 18 machines instead of 1, and will give everyone better response times/performance.

Getting lab feedback

I'll post a unique directory for each student that contains their feedback on lab exercises, and will regularly update those as the term progresses. (It currently contains feedback on your submission of the labex0 exercise and possible bonus mark.)

To set up initial access to this, run the following two commands

cd
git clone csci:csci159/$USER/feedback csci159/feedback

Any time during the term that you want to check for updated feedback use the following command sequence:

cd
cd csci159/feedback
git pull

The "git pull" checks for updates and copies them to your directory, where they will be stored in files named after the lab exercise, e.g. lab1, lab2, etc.

You can look at these files with any text editor to see the feedback I've given on the lab.

X2Go

In the linux lab (room 102) we can use any of the graphical utilities normally, but when ssh'ing from a Windows machine those commands won't work directly since our servers don't have permissions to open new windows on another machine.

When on a Windows machine, you can actually use another program, X2Go, that allows you to open a graphical connection to the csci linux servers.

We'll give a condensed "how to" below, but a more detailed discussion can be found at csci.viu.ca/~kabirh/courses/csci331/projects/RemoteAccessX2Go.pdf

Steps

Configuring an x2go session

left click the Windows icon and find the X2Go Client program in the programs list, start the program
click on session and new session
type a session name, e.g. pup7 if you plan on connecting to pup7
use the full name for the host, e.g. pup7.csci.viu.ca
enter you linux userid in the login box
leave 22 as the ssh port
check "use proxy server for ssh connection"
leave ssh as the proxy type
check "same login as on x2go server"
check "same password as on x2go server"
enter csci.viu.ca as the proxy server host
leave port 22 as the proxy server port
choose MATE as the session type from the drop down list (don't check x2gkdrive)
under the connection tab, select 4k-png for compression
click ok to save the session configuration
Running an x2go session
click on the session you just created
enter your linux password and click ok
answer yes if asked do you trust the host
after a lengthy pause, a graphical interface to the linux server will open, showing your home directory

you can use the menus at the top of the new window to open (MATE) terminal windows to enter linux commands, to open specific applications, to change your settings, etc.

This new window looks like the desktop you'll see if you go to our linux lab, room 102 in building 315

Feel free to browse and experiment, perhaps try out the gedit editor as an alternative to pico, e.g.

cd
cd csci159
cd lab1
gedit lab1a.cpp

Ending the x2go session

From the System menu in the x2go window, select the logout option