Using the CVL

CVL Introduction

The CVL runs on Linux/Unix servers, primarily CentOS (a Red Hat derivative). As such, familiarity with the Unix command-line is a useful skill.
You can access the CVL and it's software while working on a project from home or campus. This generally comes in either command-line form or as a graphical application launched via the command-line (referred to as a "shell"). There are many tutorials from which you can familiarize yourself with the basic unix commands that can be performed via the command-line shell. Fortunately, not very many of these command-line utilities are required to access and use the CVL software.

The most general commands you use to navigate the file system are:
- ls: listing the files in your home directory
- cd: changing directory
- mkdir: making project directories
- mv: moving files in and out of the directories

Here are some examples of tutorials:

The standard way to connect to the CVL remotely is with the program called "Secure Shell" (SSH), which has wide support on many operating systems. SSH establishes a secure, encrypted connection from the local shell to a command shell on a remote machine, and even allows for file transfers over the same encrypted channel.

Applications on Unix are not restricted to just command-line programs!

The Unix standard for graphical applications is called "X-windows," or just "X" for short. In fact, the graphics capabilities of this X-windows system are much more flexible than in the Windows or MacOS because they allow for interactions (viewing windows, buttons, pointing, clicking, etc) on a different machine than the one running the application. All that is required is a network connection between the two, and what's referred to as an "X-server" on the local machine that allows the user to physically view the windows and manipulate the mouse. This "client/server" naming convention seems backwards in that the "server" runs on the local computer (e.g. your Windows laptop), and the "client" is the application running on the CVL (e.g. Matlab). Linux clients generally have this X-server installed by default, but Windows users have to install one if graphical access to the CVL is required.

In order to access the CVL from a Windows system, you must have a SSH client and a X-windows server installed on your Windows machine. We recommend using MobaXterm, an all-in-one program that lets you SSH with X11-Fowarding enabled, and lets you copy files to and from your Windows machine to the remote server.

MobaXterm

  ssh -X cvl.ece.vt.edu

To copy a file from your local computer to your CVL home directory, type the following command:

  scp -r localfile cvl.ece.vt.edu:

To copy a file from your CVL home directory to your local computer, type the following command:

  scp -r cvl.ece.vt.edu:remotefile ~/