Reading 00: Command-Line, Git

Everyone:

Welcome to CSE 20289 Systems Programming, which (as the syllabus states) is a course that "introduces students to the Unix programming environment where they will explore various command line utilities, files, processes, memory management, system calls, data structures, networking, and concurrency". What this means is that you will first learn how to effectively utilize a modern Unix programming environment and then you will study how to develop applications that take advantage of system level abstractions such as files, processes, and sockets.

Course Overview

Last semester, most of you took the CSE 20311 Fundamentals of Computing course where you learned how to program in the C++ language. After playing the Game of Life, generating anagrams, and building fractals, you should be capable of programming in a compiled language using conditional statements, loops, functions, and classes. Moreover, you should be somewhat familiar with strings, arrays, and those crazy pointers.

In this class, we will build on this foundational knowledge by exploring the Unix programming environment in order to get a better idea of how a computer works and how to build applications that utilize different aspects of traditional software and hardware systems. The semester can be broken down into the following sections:

1. Using the Shell

   We will begin by learning how to utilize the Unix shell and then how to compose multiple Unix utilities into pipelines and then shell scripts.

2. Python Scripting

   Next, we will explore scraping, visualizing, and processing data using Python. Along the way, we will discuss functional programming, parallel computing, and distributed computing and use these techniques to brute-force crack passwords.

3. C Programming

   After Spring Break, we will descend down the software stack to C and discuss memory management and data representation as well as revisiting pointers, strings, arrays, and studying some data structures.

4. System Calls

   Finally, we will build our own Unix applications that take advantage of system level abstractions such as files, processes, and sockets through the use of system calls. All of this exploration will culminate in a HTTP client and server.

Moreover, throughout the course, we will frequently examine the wisdom and power of the Unix Philosophy:

1. Write programs that do one thing and do it well.

2. Write programs to work together.

3. Write programs to handle text streams, because that is a universal interface.

Each week there will be a reading assignment meant to give you a context and reference into what we will be covering that upcoming week and a homework assignment that will provide you an opportunity apply the material in (hopefully) interesting ways. Of course, there are three exams to assess your mastery of the material.

Readings

The readings for Friday, January 18 are:

1. The Linux Command Line

   • Chapter 1 - What is the Shell?
   • Chapter 2 - Navigation
   • Chapter 3 - Exploring the System
   • Chapter 4 - Manipulating Files and Directories

   • Chapter 5 - Working With Commands
     

2. Git Handbook

   Note, although we will be using GitLab instead of GitHub, most of the documentation for git, including this handy cheatsheet works on either platform.

3. Pro Git

   • Chapter 1 - Getting Started
   • Chapter 2 - Git Basics
   • Chapter 3 - Git Branching

The focus of the readings is to review the basics of using the Unix shell, which most of you used in CSE 20311 Fundamentals of Computing last semester, and to introduce you to Git, which we will be using throughout the semester.

In addition to reading the above chapters, it is recommended that you work through the following tutorials:

1. Command Line Crash Course

   This is a tutorial on using the command line interface on various operating systems (you should focus on the Unix shell).

2. Learn Git Branching

   This is an interactive tutorial on branching in Git.

Additional Resources

The following are additional resources that you may find useful:

Unix Shell

• Learning the Shell

• Survival guide for Unix newbies

Git

• gittutorial

• Start using Git on the command line

GitLab

Normally, you would have quiz to complete after each reading. For this first assignment, however, you only need to create your own private assignments Git repository on GitLab by following the instructions below:

Task 0: Create GitLab Account

The first step is to create a GitLab account if you don't have one already. GitLab is a code hosting repository similar to Bitbucket and GitHub. We will be using GitLab this semester since it provides for unlimited private repositories and no restrictions on the number of collaborators. Likewise, GitLab has built-in for continuous integration which will be using later in this course.

To create an account, go to https://gitlab.com/users/sign_in and follow the prompts there.

Task 1: Fork Assignments Repository

Once you are signed up and have logged in, go to the class assignments repository located at: https://gitlab.com/nd-cse-20289-sp19/cse-20289-sp19-assignments and click on the Fork button. This will create a copy of the original assignments repository to your personal GitLab account.

Task 2: Configure Repository Settings

Next, you will configure the assignments repository so that it is private. That is, only you and the instructional staff should have access to it. To do this, click on the Settings gear on the bottom left-hand side of the project page, and then select General.

You will then be taken to the Project settings page for the repository. Expand the Permissions section and set your Project Visibility to Private and then scroll down and click the green Save Changes button.

Afterwards, expand the General project settings settings and add your name and netid to the Project description. Once you have made these changes, make sure you scroll down and click on the Save changes button.

Task 3: Add Instructional Staff

Next, you will ensure that the instructional staff has access to your repository by clicking on the Settings gear on the bottom left-hand side of the project page and select Members.

This will take you to the page to add new users to the project. You will need to add all of the instructional staff as part of your project (both instructors and all the teaching assistants):

1. Alex Ayala (@aayala4)
2. Catalina Vajiac (@catvajiac)
3. Conor Nailos (@cnailos)
4. Edoardo Bianchi (@ebianchi98)
5. Emily Strout (@estrout)
6. Grace Milton (@gmilton)
7. Jack Collins (@JaCollins)
8. Joo Yun (Rosa) Kim (@jkim63)
9. Kathleen Capella (@kcapella)
10. Kyle Miller (@myle_killer)
11. Logan Yokum (@lyokum)
12. Michael Moynihan (@mmoyniha)
13. Peter Bui (@pbui)
14. William Diederich (@wdiederi)

Each instructional staff member should be given Developer access and an expiration date of 2019-06-01.

Task 4: Clone Repository

Once you have a private fork of the assignments repository and have configured it properly, you should clone it to your local workspace. This workspace can either be on the student machines, a virtual machine, or your personal machine.

To do this, copy the URL from the Project summary page and perform the clone command using Git on your desired platform. You will now have a local clone of the repository you can work with:

# Example on a student machine

$ git clone https://pbui@gitlab.com/pbui/cse-20289-sp19-assignments.git # Clone the remote repository to the student machine
Cloning into 'cse-20289-sp19-assignments'...

(gnome-ssh-askpass:31733): Gtk-WARNING **: cannot open display:
error: unable to read askpass response from '/usr/libexec/openssh/gnome-ssh-askpass'
Password for 'https://pbui@gitlab.com':

remote: Counting objects: 47, done.
remote: Compressing objects: 100% (7/7), done.
remote: Total 47 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (47/47), done.
Checking connectivity... done

$ git clone https://$USERNAME@gitlab.com/$USERNAME/cse-20289-sp19-assignments.git

$ unsetenv SSH_ASKPASS

Task 5: Commit First Change

Your final task is to practice using Git by editing the README.md file in the assignments repository such that the Name and NetID fields are completed (i.e. replace "Domer McDomerson" and "dmcdomer"). You should commit your change and then push them to GitLab.

# Example on a student machine

$ cd cse-20289-sp19-assignments   # Go into the assignments directory

$ nano README.md                  # Edit the README.md file

$ git add README.md               # Mark the file for recording

$ git commit -m "Update README"   # Record the change
[master c550fa1] Update README
1 file changed, 2 insertions(+), 2 deletions(-)

$ git push                        # Send your local changes to GitLab
(gnome-ssh-askpass:1030): Gtk-WARNING **: cannot open display:
error: unable to read askpass response from '/usr/libexec/openssh/gnome-ssh-askpass'
Password for 'https://pbui@gitlab.com':

Counting objects: 5, done.
Delta compression using up to 12 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 325 bytes | 0 bytes/s, done.
Total 3 (delta 2), reused 0 (delta 0)
To https://pbui@gitlab.com/pbui/cse-20289-sp19-assignments.git
  2d0303d..c550fa1  master -> master

The following is a video demonstration of the process of cloning your GitLab repository and committing your first change.