Reading 01: Using the Shell

Everyone:

Next week, we will explore how to use some of the more advanced features of the Unix shell, including how to manipulate files and control processes, which are two fundamental abstractions the Unix operating system provides to the end user. You are also encouraged to learn more about a particular text editor of your choice such as vim, emacs, or nano.

Branching¶

As discussed in class, each reading and homework assignment must be completed in its own git branch; this will allow you to separate the work of each assignment and for you to use the Pull Request workflow describe at the end of this document.

To create a branch in your local repository, follow the instructions below:

$ cd path/to/cse-20289-sp22-assignments   # Go to assignments repository

$ git checkout master                     # Make sure we are in master branch

$ git pull --rebase                       # Make sure we are up-to-date with GitHub

$ git checkout -b reading01               # Create reading01 branch and check it out

$ cd reading01                            # Go into reading01 folder

Once these commands have been successfully performed, you are now ready to add, commit, and push any work required for this assignment.

$ git branch

$ git branch
  master
* reading01

$ git checkout master

Python 3¶

Throughout the semester, we will be using Python 3 for a variety of purposes. Because the student machines do not have Python 3 by default, you will need to add the following line to your ~/.bashrc file:

export PATH=/escnfs/home/pbui/pub/pkgsrc/bin:$PATH

You can then source this file to load that environment variable:

$ source ~/.bashrc

To check that Python 3 works, you can run the following:

$ python3 -V
Python 3.9.1

This will be necessary for the .scripts/check.py script in your assignments repository.

$ pip3 install requests pyyaml

Readings¶

The readings for Wednesday, January 19 are:

1. The Linux Command Line:

   • Chapter 6 - Redirection
   • Chapter 7 - Seeing the World as the Shell Sees it
   • Chapter 8 - Advanced Keyboard Tricks
   • Chapter 9 - Permissions
   • Chapter 10 - Processes

In addition to reading the above chapters, it is recommended that you learn a command-line text editor such as one of the following:

1. nano: This text editor is the easiest to get started with, but also has the least amount of features. It is what I recommend for newcomers to Linux.

   • Using Nano

   • The Beginner's Guide to Nano

2. vim: This text editor has many features such as syntax highlighting, plugins, and even spell checking. That said, it has a steep learning curve due to its foreign keyboard interface.

   • Chapter 12 - A Gentle Introduction to Vi of The Linux Command Line
   • Vim Introduction and Tutorial

   • Interactive Vim Tutorial

3. emacs: This text editor also has many features (perhaps too many). In fact, Emacs is so powerful, there is saying "Emacs is an excellent operating system. All it's missing is a decent text editor". Bazinga!

   • Absolute Beginner's Guide to Emacs

   • A Tutorial Introduction to GNU Emacs

Optional References¶

The following are additional resources that you may find useful:

1. Introduction to Linux

   • Chapter 3. About files and the file system

   • Chapter 4. Processes

Quiz¶

Once you have completed the readings, answer the following Reading 01 Quiz questions:

Submission¶

To submit your answers, you will need to create an answers.json file in the reading01 folder of your assignments repository:

1. If you have not already, follow the instructions at the top of this document to create a reading01 branch in your assignments Git repository.

2. You can either hand-write the answers.json file using your favorite text editor or you can use the online form to generate the JSON data, which should look like the following:

   {
       "q01": [
           "stdin",
           "stdout",
           "stderr"
       ],
       "q02": "yes",
       "q03": [
           "a",
           "b"
       ],
       "q04": [
           "a",
           "b"
       ],
       "q05": [
           "c"
       ],
       "q06": [
           "ls"
       ],
       "q07": [
           "beastie"
       ],
       "q08": [
           "beastie"
       ],
       "q09": [
           "beastie"
       ],
       "q10": [
           "800"
       ],
       "q11": [
           "b"
       ],
       "q12": [
           "homeworks"
       ]
   }
   

   To determine which symbols correspond to which response, take a look at the Reading 01 Quiz file.

   To check your answers, you can use the provided .scripts/check.py script:

   $ cd reading01                        # Go into reading01 folder
   
   $ $EDITOR answers.json                # Edit your answers.json file
   
   $ ../.scripts/check.py                # Check reading01 quiz
   Checking reading01 quiz ...
        Q01 0.90
        Q02 0.10
        Q03 0.10
        Q04 0.10
        Q05 0.10
        Q06 0.40
        Q07 0.20
        Q08 0.20
        Q09 0.20
        Q10 0.60
        Q11 0.60
        Q12 0.50
      Score 4.00 / 4.00
     Status Success
   

   This script will check your responses by sending your reading01/answers.json file to dredd, which is the automated grading system. dredd will take your answers and return to you a score and overall status as shown above.

   Note: The Score denotes how many points you received out of the maximum number of attempted points, while Status is Success if you have achieved full credit (otherwise, it will show Failure).

   Try, Try, Try Again¶

   You may check your quiz answers as many times as you want; dredd does not keep track of who submits what or how many times. It simply returns a score.

3. Once you have your answers file, you need to add, commit the file, and push your commits to GitHub:

   $ git add answers.json                # Add answers.json to staging area
   
   $ git commit -m "Reading 01: Done"    # Commit work
   
   $ git push -u origin reading01        # Push branch to GitHub
   

   Iterative Approach¶

   You may edit and commit changes to your branch as many times as you wish. Just make sure all of your work goes in the appropriate branch and then perform a git push when you are done.

4. When you are ready for your final submission, you need to create a Pull Request via the GitHub interface:

   • If you have a Compare & pull request button corresponding to your reading01 branch on your repository page, then you can click on that button.

     

     Pull Request URL¶

     As an alternative, when you first do a git push on the command-line, git will also give you a URL that you can click to create a Pull Request.

   • If you do not have the Compare & pull request button, then go to your repository's Branches page and then press the New pull request button for the appropriate branch:

     

   • Next, edit the Pull Request title to "Reading 01", write a comment if necessary, assign the appropriate TA, and then press the "Create pull request" button.

     

   • Every commit on GitHub will automatically submit your quiz or code to dredd and the results of each run is displayed in the Checks tab of each commit as shown below:

     

Once you have made the Pull Request, the TA can verify your work and provide feedback via the discussion form inside the Pull Request. If necessary, you can update your submission by simply commit and pushing to the appropriate branch; the Pull Request will automatically be updated to match your latest work.