Week 7 – Doing it All from the Command Line (2024)

Lecture Materials

About Git
Git (You don't necessarily have to install this on its own for your computer; but this is the link to the underlying tool called git. It's included in Github Desktop.)
Vim

Lab Tasks

Discuss with your group:

This lab will be focused on doing all the tasks we've been doing so far solelyfrom the command line. That means using vim for editing and the git commandline tools for cloning and pushing.

Editing from the command line: vim

Log into ieng6. Run the command vimtutor. Set a timer for 20 minutes.

Complete the first two lessons (go past lesson 2 if you can in 20 minutes).Really do the exercises!

After the 20 minutes are up, clone this repository which has a subset of thecode from the week 3 lab:

$ git clone https://github.com/ucsd-cse15l-s24/lab7

Then, in pairs, you are going to write down exactly the keys to press tomake an edit to fix the test. You'll share these instructions in your shared labdoc, and the next group is going to use them to try and replicate what you did.

So: Fix the program using what you learned about vim in the tutorial (as areminder, you're changing the index1 to index2 in ListExamples.java). Re-run the tests to make sure it works. Keep extremely accurate track ofwhat you had to type to make this happen. You might even want to change the fileback to its initial state (u is the command for undo in vim) anddouble-check that the instructions you are giving are good. When you'resatisfied, write down the list of keys that need to be pressed (including alluses of Backspace, Enter, Escape, and so on!) in the shared notes doc. Have onepartner in your pair do this typing; the other partner shouldn't make the editsyet because they will in the next step.

Then, go around the groups one at a time. The group to your left should use yourinstructions to try and make the edit, then the next group to their left willuse their instructions, and so on. Watch carefully! Was each group able to? Whyor why not? Did the group typing do something that didn't match theinstructions, were the instructions not complete, or did something else happen?Don't leave any mysteries!

You can press Ctrl (or Cmd)-Shift-p and start typing "screencast" to turn onscreencasting mode so others can see what you type.

Discuss and refine: After you do this, discuss how you could make theprocess easier. Did you have to press the arrow keys a lot? Are there vimcommands that could have improved the process? How short of a key sequence canyou make it to perform this edit? Can you get it under 20 keypresses includingsave and exit? Under 15?

If you finish quickly and want to practice more, each group can choose oneof the following tasks, and repeat this whole process (design the keys to pressin pairs, write them down in the notes, then go around and try the instructionsone pair at a time, with others looking on and observing).

In ListExamples.java, change the name of the sc parameter offilter, and all of its uses, to instead be called checker.
In ListExamples.java, add a new line at the top of the first while loop in merge that prints out the current values of index1 and index2.
In ListExamplesTests.java, add a test for merge on two empty lists.

After watching the other groups do their work, can you think of any ways toimprove your instructions?

Speeding up Command Line Tasks

There are many things we can do to speed up working with the command line,making it more efficient and easy to use. Working quickly can dramaticallychange how difficult future programming tasks are for you, so it's worthspending time getting better at using your tools.

In this lab, you’re going to learn how to make this process a lot easier foryou. Then, you will measure your improvement as you learn to complete thecommand line tasks most efficiently. As you do this, check in with the people inyour group to see how they are doing things more or less efficiently than you,and share tips.

Timing Tasks

In this section, you will be timing yourself while performing a set of tasks. The tasks you will be performing will include forking a repository, cloning the fork using the SSH url, running a set of JUnit tests to demonstrate that they fail,fixing the bug using the vim editor and then re-running the tests.

Before we get to that though, there are few things that you will need to setup that willhelp you save a lot of time!

Generating SSH Keys for ieng6

If you haven't yet, go back to the week 3laband make sure you are set up to SSH without a password using keys!

Generating SSH Keys for GitHub

You can access and write data in repositories on GitHub.com using SSH. When youconnect via SSH, you authenticate using a private key file on your localmachine, which in our case will be the ieng6 machine.

Create a private SSH key file on ieng6. This is a new private key just foraccessing Github from your course-specific account.

Login to ieng6 as usual (hopefully, without typing a password now!)
Run the command ssh-keygen, and again press Enter until the command completes and shows the "randomart image"

Next, we want to add the public key to your Github account. This is likethe step of copying the public key to authorized_keys on ieng6, but insteadwe're copying to Github.

Display the SSH public key generated above to your clipboard using cat likebelow; you can copy it by highlighting and right-clicking
- cat <path of your ssh key .pub file>
Open your Github account on the browser.
In the upper right corner, click on your profile photo, then click Settings.
In the “Access” section of the sidebar, click SSH and GPG keys.
Click New SSH key or Add SSH key under the “SSH keys” section.
Add a “Title” to your key (ex: Your Name’s ieng6 machine).
Select the “Key Type” to be an Authentication Key
Copy your public key from the output of the cat command and paste it into the “Key” field
Click Add SSH key.
If prompted, confirm access to your account on Github.

Go back to the ieng6 terminal and:

Run the following command to add Github.com as a recognized host (this avoidsthe scary yes/no prompt about accepting new connections the first time youconnect)
- ssh-keyscan -t rsa github.com >> ~/.ssh/known_hosts
- >> means "append stdout of the command to file"
Check your connection by running the following command:
- ssh -T git@github.com
- It will say something like "Hi supercoolstudent1234! You've successfully authenticated, but GitHub does not provide shell access."

Now we have an SSH key which can be used to authenticate to GitHub! In addition tousing https clone URLs, we can now use SSH clone URLs that look like this:

Crucially, these will allow both cloning and pushing to the repository (aslong as your account has access). With this done, try cloning your fork ofthe lab 7 repository (make a fork if you didn't already), then making a smallchange, and pushing it with the command line.

Important: For the rest of the lab, make sure to clone using the SSH clone URLs as described above!

If you're not sure how to add, commit, and push from the command line, refer to the week 4 lab. You can alsolook at this past lecture video.

Make sure you can make a change to your repository by editing, adding, andpushing all from the command line before going on!

Baseline

Let the time trials begin!

First, we'll take a baseline measurement of performing the tasks above by timingyourself. Your phone may have a timer app, or you can find one by searching foronline timers. The steps from above are duplicated here:

Setup Delete any existing forks of the repository you have on your account. See this Githublink on how to delete forks.
Setup Fork the repository
The real deal Start the timer!
Log into ieng6
Clone your fork of the repository from your Github account (using the SSH URL)
Run the tests, demonstrating that they fail
Edit the code file to fix the failing test
Run the tests, demonstrating that they now succeed
Commit and push the resulting change to your Github account (you can pick any commit message!)

Write down in notes: What was your baseline time? Did your lab partner havea faster baseline than you? If so, do they have any tips to help you getstarted on boosting your efficiency?

Speeding Up

Now, you will explore various ways that you can speed up your work. Try all thesteps below, and find out what works best (and what doesn’t work) for you!

Using Bash History (up/down arrows)
- You can use the “up” and “down” arrows to go through the history ofcommands you have executed, it makes executing the same command much easier!If you run the commands you care about, then log out and back in, they arestill in the command history!
- You can use Ctrl-R to search your command history. At the bash prompt,type Ctrl-R and then start typing part of a command – what shows up?Experiment with using Ctrl-R
Using Tab
- You can use the Tab key to speed up typing commands in the command line inthe following ways:
  - Start typing the first few letters of a command or path. Pressing tabonce will autofill the rest of the line up to the point where there aremultiple potential possibilities. If you press tab a second time, it willshow you all of the possibilities for what it could autocomplete to.
Keyboard Shortcuts while editing commands
- More details at: https://www.redhat.com/sysadmin/shortcuts-command-line-navigation
- Have you had a time where you mistyped one of the commands and had to backspace all the way back to fix the problem? There’s a better way!
  - Ctrl-U deletes everything from the current cursor position to the beginning of the line
  - Ctrl-K deletes everything from the current cursor position to the end of the line
  - Ctrl-A goes back to the beginning of the line
  - Ctrl-E goes to the end of the line
  - Ctrl-W deletes the last word
  - Alt-Left/Alt-Right (Windows) or Option-Left/Option-Right (Mac) to move by word
  - Click the “left” or “right” arrow to go to the left/right end of any selection!
Quick Copy/Paste
- Use these keyboard shortcuts to highlight text quicker:
  - Double click – selects an entire word
  - Triple click - selects an entire paragraph
  - Alt+Shift-Left/Alt+Shift-Right (Windows) orOption+Shift-Left/Option+Shift-Right (Mac) - select multiple words
- On Mac:
  - Command-C to copy
  - Command-V to paste
- On Windows:
  - Ctrl-C to copy
  - Ctrl-V to paste
  - Right click to paste in Windows terminal

New PR!

After practicing with the above, time yourself again doing the same tasks. Don'tforget to delete and re-fork the repository before timing!

Write down in notes: How much were you able to improve from your baseline?

Lab Report 4 - Vim (Week 7)

For the lab report this week, reproduce the task from above on your own.

Instructions:

For each numbered step starting right after the timer (so steps 4-9),

Take a screenshot
Write down exactly which keys you pressed to get to that step, including <enter> and <space> (e.g., cd<space>L<tab><enter> or <down><down><down><down><down><down><down><enter>). For special characters like <enter> or <tab>, write them in angle brackets with code formatting.
Then, summarize the commands you ran and what the effect of those keypresses were.

For example, when you run the tests, you might want to use the up arrow orCtrl-R to access your bash history rather than typing in the full command withclasspath, etc. You might say something like this accompanying the screenshotfor running the tests:

Keys pressed:<up><up><up><up><enter>, <up><up><up><up><enter>The javac -cp .:lib/hamcrest-core-1.3.jar:lib/junit-4.13.2.jar *.java commandwas 4 up in the search history, so I used up arrow to access it. Then the java -cp .:lib/hamcrest-core-1.3.jar:lib/junit-4.13.2.jar org.junit.runner.JUnitCore ... command was 4 up in the history, so I accessedand ran it in the same way.

Add this lab report to your Github Pages site, and submit a PDF of it as usual.