This pseudo-lab is to be done on your own. There are no lab meetings for this lab. There is no check-off or other grade process for this lab.
SSH (Secure SHell) is a ubiquitous tool for running arbitrary programs on remote machines. We will use it extensively this semester. It comes bundled with a few related tools, like SCP (Secure CoPy), that we will also use.
You’ll need to know how to run SSH:
| If you are running | Then you should use |
|---|---|
| Linux | open a terminal and use the built-in ssh command |
| MacOS | open the Terminal app, then use the built-in ssh command |
| Windows 10 | install OpenSSH Client (following the from the Settings UIdirections) once; then open the PowerShell app and use the ssh command |
| Haiku | open a terminal and use the built-in ssh command |
| FreeBSD | open a terminal and use the built-in ssh command |
| OpenBSD | open a terminal and use the built-in ssh command |
| Irix | open a terminal and use the built-in ssh command |
SSH gives you a shell; shells have long been ubiquitous tools in all systems except Windows, and they are increasingly used in Windows too. The shell is sometimes also called the command line
or the console
.
Visit http://web.mit.edu/mprat/Public/web/Terminus/Web/main.html, a somewhat cheesy introduction to the basics of the command line. Explore it until you
ls, pwd, cd (including cd ..), and lessmv and manThere is a lot more you can do (creating a magic locker, explore a hidden tunnel, learn about grep and rm, etc.) but those are the most important basics.
Avoiding excessive typing
While in a shell, there are several keys to make you life easier; the most important are
Pressing the tab key when the cursor is preceded by an incomplete word that can only be completed in one way will fill in the rest of the word.
Pressing tab twice when the cursor is preceded by an incomplete word that can be completed in several ways lists all of the completions the command line knows about.
Visit http://overthewire.org/wargames/ and read. Many of the pages list web resources to help you learn more.
If you don’t like reading, you can skip ahead to
and consult http://overthewire.org/wargames/bandit/bandit0.html to get started.
We suggest getting to level 4 of Bandit, though you might find other levels and games there interesting.
At some point you should get an email from the CS department with a CS login. You should be able to use that to SSH into mst3k@portal.cs.virginia.edu, an account we will use many times this semester.
To reset your password, use the password reset tool at https://www.cs.virginia.edu/PasswordReset/. This tool will not work unless your account was setup at some point, a task that typically happens 3-5 days after you add the class.
Sometimes you need to edit a file on a remote computer over SSH. We’ll see other ways of doing this as the semester progresses, but you’ll often need to work in a command-line interface (CLI).
A text editor is a tool designed for editing text, only. They typically provide programming language syntax highlighting (i.e., strings show up in a different color from integers) and sometimes other customizable features, but typically do no have error checking, compiling, executing, and other features of an IDE.
There are three main CLI editors in common use today; pick one to learn. We recommend GNU nano if you want your learning to be over quickly or VI if you want to have a lot of power after you learn.
EMACS was one of the first widely-used powerful CLI editors (released 1976). It has a large set of features and an idiosyncratic set of commands, many of which involve pressing Ctrl+X followed by another Ctrl+something command.
As EMACS has lost popularity in the past decade, more and more servers choose not to install it.
EMACS comes with Linux, and can be downloaded for Windows and obtained via homebrew for MacOS: https://www.gnu.org/software/emacs/download.html
VI (released 1979), or more commonly the updated version VIM, is probably the most widely used CLI editor today. It has a large set of features and an idiosyncratic set of commands involving two modes: normal
mode where virtually every letter and number key has a special meaning and often a special meaning in a sequence and insert
mode where those same keys instead type.
To begin learning VI, go to https://www.openvim.com/ and follow along. Then open a shell (or the equivalent on your own machine if you’ve installed VI), type vim, and try it out. You’ll probably need a cheat-sheet to remember all the keys: https://vim.rtorr.com/.
You can also try running vimtutor from a shell for a different approach to learning VI.
VI comes with Linux and MacOS, and can be downloaded for Windows: https://www.vim.org/download.php
GNU nano (released 2000) is a much simpler (i.e. both easier to learn and less powerful) editor than the other two, with more traditional key commands and an on-screen summary of the most-used commands.
To learn nano, open a shell (or the equivalent on your own machine if you’ve installed nano), type nano, and follow the on-screen instructions.
Note that in the instructions ^X means Ctrl+X and M-X means Alt+X (or Esc X if you are on MacOS and Alt does not work for you).
Nano comes with Linux and an old version comes with MacOS; it can be downloaded for Windows (via the chocolatey package manager) by typing the following two lines into the PowerShell app:
Set-ExecutionPolicy Bypass -Scope Process -Force; iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))choco install nanoBecome sufficiently familiar with at least one of these editors that you can open, modify, and save files.