By default, connecting to one of Purdue CS servers via SSH involves typing ssh <username>@<machine>.cs.purdue.edu followed by <password>,PUSH and authorizing on Duo Mobile. However, there is a faster and more secure way of connecting to SSH servers.

In this post, I will show you how to generate an public-private SSH key pair in your local machine using OpenSSH, add the public key to Purdue server, and use the key pair to automatically authenticate.

1. In your local machine, use the following ssh-keygen command:

   ssh-keygen -t rsa -b 4096 -C "Theo's RSA Key for Purdue CS servers authentication"
   

   Explanation:

   • -t rsa: specifies the encryption algorithm to use. In this tutorial, we use RSA since it's the most widely available encryption, but if your machine supports it, I recommend using a stronger algorithm like ed25519. See man ssh-keygen for more information.
   • -b 4096: specifies the number of bits the RSA algorithm will use. By default, RSA uses fewer bits than 4096. Other algorithms like ed25519 have a fixed number of bits, and this flag will be ignored
   • -C "...": add a comment to the end of the public key

2. Follow the prompts for generating the key pair:

   Generating public/private rsa key pair.
   Enter file in which to save the key (/home/<your-username>/.ssh/id_rsa): [Press Enter]
   
   Enter passphrase (empty for no passphrase): [Type a passphrase]
   Enter same passphrase again: [Type passphrase again]
   

   Now, when you cd ~/.ssh, you will see two files:

   • id_rsa: This is your private key. Do not share this with anyone.
   • id_rsa.pub: this is your public key; you will share this with other people.

   If you want to learn more about public-key cryptography, here is the slide from UIUC CS407. Also, consider taking CS426: Computer Security or CS355: Cryptography if you are interested in this topic!

3. Now we are going to copy the SSH key to the Purdue CS server with the following command:

   ssh-copy-id -i ~/.ssh/id_rsa.pub <PURDUE_USERNAME>@data.cs.purdue.edu
   

   Follow the instructions to log in to the server. This will copy your public RSA key to ~/.ssh/authorized_keys in the Purdue server.

   Test by SSH-ing into any of the servers (e.g., ssh me@data.cs.purdue.edu). If the key was copied correctly, it will ask for the passphrase for the RSA key.

   *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
   -                  Password-only logins have been disabled                 *
   *   Use of Duo Mobile, a hardware token, or an SSH key pair now required   -
   -   Duo Mobile: Enter your password followed by a comma followed by PUSH   *
   *  Token: Enter your password followed by a comma followed by 6-digit code -
   -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
   Enter passphrase for key '/home/theopn/.ssh/id_rsa':  [Your SSH Key password and not <Purdue password,PUSH>]
   

4. To eliminate the need to type in a passphrase each time, we will add the keys to the ssh-agent. If you use macOS, execute the following commands.

   eval "$(ssh-agent -s)"
   ssh-add --apple-use-keychain ~/.ssh/id_rsa
   

   In short, ssh-agent is a daemon (background service) that automatically authenticates keys. For Linux, I recommend using Keychain by Daniel Robbins.

   Again, man command (man ssh-agent and man ssh-add) is your best friend.

5. Finally, we will add the settings and alias in ~/.ssh/config:

   cat <<HI >> ~/.ssh/config
   Host data
       Hostname data.cs.purdue.edu
       User <PURDUE_USERNAME>
       IdentityFile ~/.ssh/id_rsa
       AddKeysToAgent yes
       UseKeychain yes
   HI
   

   I am using Bash's Heredoc to generate a multi-line file.

Now you can simply execute ssh data, and you will be connected to the server without needing to pick your phone up or even type in a password. Thanks to public-key cryptography (unless your laptop is physically compromised), it is a more secure option, too.

Computer Science Undergraduate Student Board Constitution

Revision 1/2/2022

Article I

Name

The name of this organization shall be the Computer Science Undergraduate Student Board.

Article II

Purposes

The Purdue Department of Computer Science is ever-growing and improving, and this growth requires active student involvement and assistance. The Computer Science Undergraduate Student Board (USB) exists to promote a supportive and engaged community within Purdue's Computer Science Department, and to use its relationship with faculty, the Computer Science Corporate Partners Program, and administration to advocate for the student body. The goals of the board include:

• Reducing the communication gap between the students and the faculty by representing the concerns of the students,
• Facilitating the flow of communication between the faculty, staff, corporate partners and the students,
• Providing the student body with a means of affecting the policy decisions of the department,
• Allowing the students, faculty, and administration of the Computer Science Department easy access to dedicated, motivated students to help in departmental programs and recruitment operations,
• Teaching undergraduate computer science courses, mentoring or tutoring the undergraduate student body, and attending department events,
• Creating events for the undergraduate student body,
• Exposing all students to opportunities within Computer Science and Data Science at Purdue.

Article III

Membership

Membership in the Computer Science Undergraduate Student Board is open to any Purdue University Computer Science undergraduate or Data Science undergraduate student who is interested in issues and concerns with respect to computer science, the department, and the curriculum. This includes members outside of the CS/DS department who can demonstrate a vested interest in the activities of the department and a willingness to contribute to USB initiatives. This interest should be demonstrated through an interview and/or resume review, and a ⅔ agreement of their eligibility by the board. Membership and participation are free from discrimination on the basis of race, religion, color, sex, age, national origin or ancestry, genetic information, marital status, parental status, sexual orientation, gender identity and expression, disability, or status as a veteran. Members and candidates who are considered for membership of the board will be expected to show substantial interest and activity in the Computer Science department itself. New members shall be elected onto the board after an interview and application review. New member elections shall take place during the end of the spring semester, in the month of April. New candidates for board membership will be evaluated in a manner seen fit by the board, such as a resume screening and interview process. The new candidates will become official members once they attend their first meeting.

The Undergraduate Student Board shall consist of no less than six members: there shall be a minimum of two seniors, two juniors, and two sophomores among the members of the board. There shall also be a cap on the number of members. At the full capacity of 25 members, there will be a minimum of six seniors, six juniors, and six sophomores on the board. There are an additional seven positions on USB that may be filled with candidates of any year. If there is a member who was formerly a senior and continues to be a member, they do not count towards the maximum of 25 members. USB greatly benefits from long-term members as well as the diversity of opinions from students of different ages and thus, these membership rules ensure that USB will remain a reasonable size. If in the future, the board sees that its responsibilities are increasing, the board may then decide to increase this cap by voting to edit this Constitution.

New members shall be elected onto the board after an interview and resume review. New members can be added to the board at any time during the spring and fall semesters if another member is away from campus for an extended period of time. These special appointments will only take place at the discretion of the President.

If the board decides that a member should be disciplined, they may do so by a ⅔ majority vote. The first course of discipline will be a verbal warning from the President to the member in question. The second course of discipline will be a written Performance Improvement Plan (PIP) which will detail the issues and guide the member in correcting them. The PIP will be written by the President and approved by the Faculty Advisor(s). The final course of discipline is a ⅔ majority vote to remove the member.

The President reserves the right to begin disciplinary proceedings without a board vote, but the final decision must still be decided by a ⅔ majority vote by the board members. The President must inform the Faculty Advisor(s) of all discipline situations.

Should a member resign or be asked to step down over the course of the year, their spot will be open for elections in the next election cycle. If a member leaves campus for an extended period of time, their position on the board will still exist upon their return and arrival to campus, provided that proper accommodations were set up between that member and the rest of the board ahead of time.

Adjunct membership is open to any Purdue University faculty or staff member. An adjunct member may not vote or hold office. The faculty advisor holds adjunct membership rights on the board. The faculty advisor is responsible for ensuring that the board adheres to university rules and restrictions, connects the board with university faculty and staff, and advises the board about difficult decisions.

Members whose undergraduate studies exceed four years are eligible for adjunct membership on the board in their final semesters. Each member may undergo an evaluation process at the end of each year to confirm that they performed their duties in accordance with the high expectations and responsibilities placed upon a board member. During this evaluation process, a member may request to withdraw from the board. According to the results of their evaluation, a member may be asked to agree to a Performance Improvement Plan to maintain their status on the Board. Members who leave the board will do so at the end of the current semester.

One member of the USB shall be designated to act as a liaison between the USB and the Computer Science Graduate Student Board in order to promote collaboration and awareness between the two organizations. The liaison shall be appointed during the spring semester to serve until the next appointee takes on the role. The liaison shall be selected via demonstrated interest and a ⅔ majority vote; if multiple members show interest, the board should follow the election rules provided for officers in the current USB Constitution. The liaison shall attend all GSB meetings and convey relevant information to the USB when necessary. If no member shows interest in the role, then a member of the executive board should take on the position for the upcoming year, as decided by the board.

The GSB will similarly designate an individual member of their board to act as a liaison to USB meetings. This GSB member will act in the same capacity described above; they will attend USB meetings as desired, and update their board members with any relevant information. The GSB representative is strictly responsible for conveying information, and shall have no voting or otherwise administrative power within the USB.

The advisors for the Computer Science Undergraduate Student Board shall be either faculty or staff and shall be chosen by the board's members. An advisor shall serve a term until they resign or is asked to resign by the officers. While an advisor is a member of the Undergraduate Student Board, they shall only act as a liaison between the organization, the Computer Science department, and the university. The advisor may not vote, hold office, or control the organization. In addition to meeting with the advisor, the board may meet with a small group of faculty and staff members to discuss current issues in the board and in the department. This small group of faculty and staff members will then be responsible for voicing the opinions and concerns of the board to the rest of the faculty.

There shall be no membership dues or fees.

Article IV

Officers

The leadership structure of the Computer Science Undergraduate Student Board shall consist of a board President, Vice President, Treasurer, and Secretary. Voters will rank their choices of candidates from most preferred to least preferred. If no candidate wins a simple majority of first preference votes, the least popular candidate is removed from the race, and voters that most preferred that candidate will have their votes changed to their next preference. This process continues until one candidate reaches a simple majority. Candidates may vote. Members can elect themselves onto the voting ballot. Leadership positions shall last for a term of one year unless re-elected. Members serving as President or Vice President may only be re-elected once. Experience of at least two semesters on the board is required to be eligible for President and Vice President positions. If no eligible members are interested in electing themselves onto the voting ballot, the leadership positions will be opened to every member of the board, regardless of membership length.

Article V

Officers and Duties

President

• Primary contact for the board
• Coordinates communication and activities between board members
• Submits Activity Planning Forms to Purdue's Student Activities and Organizations Office
• Serves as the face of the organization for all external contacts (Faculty, Corporate Partners, etc)
• Delegates communication with external contacts to board members
• Maintains regular communication with each board member regarding their goals on the USB

Vice President

• Secondary contact
• Assists the President in their duties
• Coordinates communication and activities between board members
• Delegates tasks to board members and ensures that they are being sufficiently completed
• Assists in the donations initiative

Treasurer

• Manages finances
• Approves activity budgets and submitting reimbursement paperwork
• Keeps accounts, deposits the organization's funds, and makes expenditures in a manner approved by the Business Office for Student Organizations
• Maintains accurate financial records and creates a budget
• Can call a veto vote on any purchasing, decided by a ⅔ majority

Secretary

• Takes notes during all board meetings
• Takes notes during departmental events and/or meetings attended by the USB
• Updates website, bulletin boards, and display cases with relevant information

All board members have the responsibility of performing tasks as designated by officers and are expected to accomplish all of the goals of the board. Attendance is mandatory for all meetings. An absence is only considered excused if the member notifies the president at least 24 hours in advance of the meeting and the absence is approved by the president. Each member is allotted three excused absences each semester.

An unexcused absence is defined as any absence that is not excused or tardiness beyond 5 minutes of the meeting start time. Three unexcused absences will result in an automatic vote to remove that member from the board. This vote will only take place if ⅔ of board members are present, and the vote must pass with a ⅔ majority vote from present members in order for the member to be removed from the board. Additional unexcused absences will result in further votes to remove the member.

Members with extenuating circumstances may be exempted from the attendance policy at the discretion of the president.

All expenditures above $500 must be approved with a ½ majority vote from present members in order to be approved. There will be at minimum one day advance written notice given to all board members of an expenditure above $500 vote before the next meeting.

Article VI

Amendments

Amendments to the constitution shall be approved by a ⅔ majority vote of the members present at time of elections. There will be at minimum one week advance written notice given to all board members of an amendment election. Only physically present members are eligible to cast a vote. All amendments to the constitution and bylaws are subject to the approval of the Office of Student Activities and Organizations. Amendments may not take effect until they have been approved.

---

Date of Adoption: _________ Date of Recognition: _________

Student Activities and Organizations Office Signature: _________ Advisor's Signature: _________ President's Signature: _________ Vice President's Signature: _________ Member Signatures: _________

It's spring semester, and I am still searching for sort of technical experience for the summer. What should I do?

Important note – a "productive" summer doesn't have to involve an internship or technical work! But for someone who's still searching for a summer resume-building activity in the Spring semester, there are opportunities (many of which are offered by Purdue) that still available.

Finding a Summer Internship

The myCCO (Center for Career Opportunities) Website

The CCO doesn't always have CS/DS specific resources and opportunities, but it is the best place to find centralized job listings.

Tips for optimal job search using the myCCO job search tool:

• Filter job results by "Posted In Last 24 Hours". Most companies post job listings and collect applicants within a span of few days, so finding newly posted listings gives you a better chance of hearing a response.
• Search jobs by "Desired Majors" rather than "Job Function" – some roles may sound non-technical at first.

Spring Career Fairs & Company Days

Every spring semester, Purdue has a "Just In Time" career fair. These companies are looking to fill positions right away, and many are looking for CS/DS students. The CCO also hosts career fairs in the spring.

Attend as many spring company days as possible. Company days have lower attendance in spring semesters than in fall semesters –– attending them is a great opportunity to get more 1-on-1 time with recruiters or company representatives. Look out for notifications about company days in the Opportunity Update that is sent out to CS/DS majors!

Research Opportunities

Many students are interested in research, but are unsure about how to get started. The summer is a great time to explore research.

390 Research Courses

Some 390s are course numbers for research work. Once you have contacted a professor or lab and been invited to do research work, you can arrange to enroll in a 390 course during the summer term. More on finding labs with open positions below.

CS 390s

If you are enrolled in a CS or DS course, chances are your professor either is involved in research, or knows another professor who is doing research. Talking with your professors about their research work and asking if they have openings for you to get involved is a great way to get your foot in the door.

If talking with professors in person sounds daunting, the CS Department Website has a compiled list of research areas and descriptions, the labs and professors doing research in each area, and contact information. Reach out using the contact information from these listings.

Other Department 390s

You don't have to limit your research search to the CS department. Many other departments are looking for CS/DS students, and even if they have not specifically posted an opening for a CS student, it is likely that they could benefit from taking on someone with technical skills.

The Pyschology Department, for example, has research opportunities listed on this website.

EPICS, VIP, and other structured programs

There are structured Purdue programs where you can do technical projects and research as well.

EPICS

EPICS is a service-learning design program for Engineering Students that is also open to Computer Science and Data Science majors. There are several teams that work in various fields – each team works with a partner in the community and develops a product to address the partner's needs. To see a list of EPICS teams and their current work, visit the EPICS website.

You can enroll in EPICS as a course during the summer term. For more information on how to join, visit the EPICS Registration Information page.

VIP (Vertically Integrated Projects)

VIP is a program that provides opportunities to do research and design projects related to active research areas of Purdue faculty members. Many of the teams' work/research is focused on Data Science and Computer Science.

You can enroll in VIP as a summer term course For more information on the current teams and information on enrolling in the VIP program, visit the VIP website.

REUS (Research Experience for Undergraduates) in Computer and Information Science and Engineering

REUs are summer research programs for undergraduates studying science, engineering, or mathematics. The programs are sponsored by the National Science Foundation, and are hosted in various universities.

See the full list of programs on the NSF website.

In this tutorial, we will be cloning a Github Repository into our local machine using IntelliJ and practicing committing and pushing our changes. To recap:

• Our Github Repository is the code hosted on Github.
• Our local machine is the computer/device you are going to be editing the code on.
• The changes made on your local machine will not be sent to our github repository until they are committed and pushed.

Step 1: Clone this repository

Our first step is to clone a Github Repository onto our local machine

How to clone remote repo to local repo and manage it with IntelliJ

1. Close any projects you currently have open File -> Close Project

   You should now see the main IntelliJ screen (It looks like the picture below).

   

2. Checkout a project from Version Control. This is done from the welcome screen in Intellij! Click Check out from Version Control -> Git -> Log in to GitHub...

   

3. The URL is asking for the HTTPS clone link. You can access this link if you go to the repository you're trying to open with Intellij, click on the green 'Code' button on the top right, and then copying the HTTPS link.

   

   The Directory is where this project will be stored on YOUR computer. Specify where in your computer you'd like the project to be saved.

4. Click 'Clone'

   Enter your GitHub credentials if asked for. (Note: The order of steps 3 and 4 might be flipped)

   

5. Confirm checkout from version control. Click 'yes'

   

6. IntelliJ will now ask you if you want to customize setup or rely on the default. You can just click 'Yes' or 'Confirm' on the screens that follow

   You've successfully cloned your git repository onto your computer (and opened it in Intellij)!

   You should see the files from your git repository on your Intellij window now. Remember, we have just cloned your git repository- all changes you make to these Intellij files will STAY on your local machine unless you push them to the central repository in Github. In other words, if you change a file from your new cloned repository on IntelliJ and save that file, you will NOT see your changes if you check your Github repository online. To learn how to commit and push your changes, move on to the next step!

Step 2: Push your changes to GitHub!

After you make new changes, you must commit and push them so your Github repository will be updated. You can find Intellij's Git options on the top right of the window. Depending on which IntelliJ version you have, the icons could appear differently.

Commit and push your changes. Note: Depending on version, the pull and commit may look like blue and green arrows instead.

Only selecting 'Commit' will NOT push you changes to your Github repository!

Confirm you'd like to push changes

What's a VCS?

VCS stands for Version Control System. You can think about it like Google Docs, but for code. Unlike Google Docs, though, it tracks every change you make! VCS's are used to help manage multiple developers working on the same project, among their many other benefits. There are many VCS's available for you to use, but in this article we'll be focusing on Git.

Why use a VCS?

There are many reasons to use a VCS, and here are just a few:

• With a VCS, you can avoid losing work because of a crash or deleting a file that you didn't mean to; you can revert your code back to when it was working
• Many CS classes at Purdue require knowledge of a VCS (and of these classes, most use Git)
• It's the most common way to collaborate with code
• Most companies will expect you to be able to use a VCS
• And even if you just learn Git, the skills you learn will be transferable to other VCS's you might have to use

Git

To start using git, you must first create a repository. A repository is a folder with git functionality (it has version control now). You have to initialize git so that it'll start keeping track of everything for you. Git keeps track of things in a hidden ".git" folder within the repository folder. Git's like a program that goes in your folder and starts tracking everything you do.

This repository on your local computer will be used to track and push changes to a central repo. If you are familiar with Github, this is the central repository hosted on Github. This central repository is the place where all collaborators can push their changes to and share with others. Think of it like a folder in Google Drive, but for holding code, not documents.

On the left is our local repository stored on our computer; on the right is the central repo on Github

So how do you push the changes you made in your local repository (that lives on your own computer) to the central repository (that your collaborators can use and see)? The basic git workflow is the following:

1. Change all the files you want
2. ADD your changes
3. COMMIT the files you added
4. PUSH your commit

To clarify these terms:

• Adding a file means that you want git to pay attention to that file. You're adding that file to a list to be committed- during your next commit, the files you added will be included. Once you commit, all files are un-added and you must re-add them to include them in the next commit.
• Committing means that you want git to save your changes to the files you previously added. A commit represents all the changes to the added files- this means it includes edits, additions, and deletions of files. Once something's committed, you can always go back to that commit at any time in the future.
• Pushing is when you push all commits that haven't already been pushed to your central repository. Pushing is what actually updates your central repository, letting your collaborators view your changes.

Helpful Git Commands

git add

git commit

git status

git log

git diff

git revert

Preamble

\documentclass{article} specifies the type of document that is going to be created. The area between the \documentclass{...} and the \begin{document} is know as the preamble. In this case, it is article, which is used of scientific journals, presentations, short reports, etc. Other document types are shown in the table below:

Document Class	Purpose
article	Articles in scientific journals, presentations, short reports, program documentation, invitations, …
report	Longer reports containing several chapters, small books, thesis, …
book	Real books.
slides	Slides with big sans serif letters.
letter	Writing letters

• The top matter includes the title, author, and date. These fields are used to store information about the document. This is useful for allowing LaTeX to automatically generate a title header for your document.
• \begin{document} and \end{document} is where all the document contents are located. The information you type into your document will be stored between these two tags.

Title

• \maketitle creates a title for document with the project title, author name, and date.

Sections

There are several types of section headers to choose from. Replace the "…" with your desired section title.

• \section{...}
• \subsection{...}
• \subsubsection{...}
• \paragraph{...}
• \subparagraph{...}

What is LaTeX?

LaTeX (pronounced "Lay Tech" or "Lah Tech") is a way of creating documents, just like Microsoft Word or Google Docs. The difference is that document content and formatting are written in plain text, as opposed to showing you the formatting of the document as you type it. LaTeX is widely used in academia. Chances are that your math exams are written in LaTeX. This is due to LaTeX being great for mathematical expressions. While it might be intimidating at first, once you become familiar with it, you can create fully customized professional documents even quicker than Word or Docs.

Why am I learning this?

Learning CS and DS is not just learning how to code. There is a decent amount of theory and mathematics. You will take courses like CS 182 and CS 381 that are will require you to turn in mathematical write-ups, like proofs. Lots of statistics professors want you to type your homework, as well. LaTeX is useful in these cases. Also, technical research papers you might write in the future will likely be written in LaTeX.

What is Overleaf?

You can think of Overleaf as the equivalent of Google Docs for LaTeX. It allows for documents to be created online and edited by multiple collaborators.

Step 1: Create an Overleaf account

Purdue provides you with a free Professional Overleaf account ($30/month value). This gives you benefits like full document history, syncing with Dropbox/Github, and unlimited collaborators per project.

Be sure to use your Purdue email to receive Professional account benefits

Click here to create an Overleaf Account

Step 2: Creating your first document

1. Verify your account via email
2. Click the Project button on the top right corner
3. Click the "Create First Project" button, and select "Blank Project."

Step 3: Your first compile!

As you might have noticed, LaTeX has a lot in common with programming languages. Like Java or C, LaTeX needs to be compiled before you can see changes in your document. Change the author from your Purdue username to your full name, and click the big green "Recompile" button. This should update the document that is shown to the right. Clicking the arrow on the "Recompile" button gives you the option to automatically recompile between changes. You can enable this, if you so choose.

Step 4: Edit!

Congrats, you've created your first document on Overleaf! Now all you have to do is start writing. LaTeX is very powerful, so much that our wiki can only cover a very small percentage of what it has to offer- if you want to get a good starting point, though, head over to our LaTeX guide.

Basic UNIX Terminal Guide

pwd (Print Working Directory)

Description Prints path of current directory. (Think: what is the address of the folder I'm viewing?)

Example

pwd

ls (List)

Description Prints contents of current directory. (What stuff is in the current folder?)

Tags

• -a = all files (include hidden files)
• -l = detailed list

Arguments Path to the folder you want to see the contents of (Leave blank to see current folder contents)

Example

ls -al

cd (Change Directory)

Description Move to the specified path. (I want to go somewhere, and I need to tell the terminal where.

Arguments Exact path of the folder you want to move to, or just a subdirectory

Syntax

cd Directory

Example

cd ~/Documents

rm (Remove)

Description Permanently deletes a file or folder (No trash/recycling bin!)

Tags

• -r - Delete a folder and its contents
• -f - Stop confirmation prompt for write-protected files

Arguments Path to the folder/file you want to delete

Syntax

rm [TAGS] Path

Example

rm -rf ~/Documents/Junk

mv (Move)

Description Move an existing file somewhere else. It can also be used to rename files.

Arguments

• The file you want to move
• The destination

Example

mv ~/Documents/source/file.txt ~/Documents/destination/file.txt
mv ~/old_name.txt ~/new_name.txt

cp (Copy)

Description Copy files or folders to a new location

Syntax

cp Source Destination
cp File-1 File-2 File-3 ... Destination

Example

cp ~/Documents/source/file.txt ~/Documents/destination/file.txt
cp ~/Desktop/Name.java ~/Desktop/Age.java ~/CS180/Homework_1

clear

Description Clear the Terminal Screen

Example

$ clear

top

Description See what programs are currently running

Example

top

killall

Description Kill all programs with the specified program_name

Syntax

killall Program_Name

Example

killall firefox

touch

Description Creates a new file in the location specified in the argument

Arguments The files that are to be created

Syntax

touch File-1 File-2 File-3 ...

Example

touch ~/Documents/file1.txt ~/CS193/HW2/file2.txt

Other Contents

Files and Folders with Spaces

If a path includes files or folders with spaces, either use quotations marks (" ") or a backslash () before the space. For example:

~/"My Files"/test.txt

or

~/My\ Files/test.text

Shortcuts

• ~ - Home Directory
• . - Current Directory
• .. - Parent Directory

Aliases

Aliases are set in ~/.bashrc

Add a line to ~/.bashrc that looks like: alias <shortcut>="<command>"

Save file, tell bash to reload: $ source ~/.bashrc

Wildcards

Description Used to include a group of files with smiliar characteristics.

They can be used with nearly any UNIX command.

Example

cp ~/Desktop/*.java ~/Documents/Project

This command will copy all .java files found in the Desktop directory into the Documents/Project folder.

mv ~/Desktop/file* ~/Documents

This command will copy all files that begin with "file" in the name into the Documents directory.

Vim and Nano Customization

From Lecture 2, you should have learned about how Vim enables commands by typing colon ":" followed by your command. However, there are some commands you don't want to have to type every time. For example, it's pretty normal to want line numbers whenever you open a file. But having to type :set number every time you run Vim kinda sucks. How can we avoid this?

Your ~/.vimrc (Vim Run Control) file controls what commands will run every time Vim is invoked. You can customize it to your heart's content.

You can disable this at any time within a file by typing :set nonumber within Vim, or by deleting it from your ~/.vimrc and then re-opening Vim again.

As you can imagine, there are thousands of commands you can leverage in your ~/.vimrc file. For a great resource on customization, read this article.

A favorite quote from that article that you should definitely adhere to is:

"Don't put any lines in your vimrc that you don't understand."

For those who are using nano, here is an article about nano customization. Similar to Vim, you add your commands in your ~/.nanorc file.

What is Terminal?

When you use the terminal, you talk more directly with your computer. Think of it as a more powerful (but less friendly) finder/file explorer.

Why Use Terminal?

There are many benefits of using Terminal! Here are some important points:

• Accessibility to programmers - with terminal, you can do important things like compile source code, access other computers, and launch programs without having to open up any other programs
• Versatility + Customizability - Say you want to move all files that start with 'cool' and end with '.gif' into a folder called 'cool gifs'. With terminal, this is one command!
• Purdue CS and terminal - Most courses will have projects/tests/homeworks that assume terminal knowledge

How Do I Open a Terminal Window?

There are lots of options for Windows and Mac computers to open a terminal window! For Windows, you can open the Command Prompt program to open a terminal window and the equivalent program on Mac is Terminal. Alternatively, there are many other programs you can download such as Git Bash, which gives you a Bash terminal with extra Git functionalities.

Now What?

For many, the interface of a terminal window can be confusing at first. To utilize terminal, you must type in UNIX commands. Remember that when you're moving around in terminal, you are essentially 'clicking' folders and files like you would in File Explorer/Finder. The way you'll be interacting with terminal is by giving it commands. Here's the basic structure of Linux commands:

It'll be helpful to get comfortable with moving around with terminal before learning more difficult actions. Here's some important commands to help you get comfortable with navigating with terminal:

• pwd
• ls
• cd

More Commands

As mentioned before, one of the important benefits of using terminal is that it gives you a lot of flexibility and options- that means there are way too many available commands to talk about in this article! To get started, check out our terminal guide that'll give you some of the important UNIX commands. You can find another helpful guide here or check out our terminal cheatsheet

If you want more information about a command, use the command man to get more information about any given command. For example, man ls gives you info about the ls command.

What is Github Pages?

Github Pages allows you to easily host and publish a webpage through Github. To start, all you need is a Github account!

How Can I Set Up my GH Page?

Set up a basic webpage by completing the following steps!

Create a new repository

Push your first file to the repository's main branch. You can use our template file by saving as a markdown file (using the file extension .md)

Click on the settings tab in your repository menu

Scroll down to the section called GitHub Pages

Change the Source setting to the option called main branch and click save

At this point, you can visit https://.github.io// to view the website you just activated.

Your website is ready!

Congrats! Your webpage has been deployed successfully!

Editing my Page

Any edits to your repository should automatically reflect onto your deployed Github Page, although your changes may not load immediately. If you do not see any changes, hit CTRL + SHIFT + R (or ⌘ + SHIFT + R on macs).

If you want to continue to edit your page using Markdown (which is what index.md is using), check out this markdown guide

Want some inspiration on what to do with your new website and lots of cool free stuff? Take advantage of Github's Student Developer Pack! To do this, navigate to the GitHub Student website and follow the steps there to request access.

Introduction

PAL3.0 is Purdue's wireless network. It uses WPA2 Enterprise authentication, which means additional configurations may be needed to connect to it on Linux.

This tutorial will show you how to connect to PAL3.0 on desktop Linux. Note: Screenshots below show the GNOME 3 desktop environment. The process should be very similar to other environments.

Step 1

Open Wi-Fi settings, and select PAL3.0 in the list of available wireless networks.

Step 2

Change the following settings:

• Set "Authentication" to Protected EAP (PEAP)
• Select No CA certificate is required

After changing these settings, your options page should look like this:

Step 3

Enter your Purdue username (without "@purdue.edu") and password (regular password, NOT BoilerKey), then click "Connect."

Step 4

You should be connected to PAL3.0 in a few seconds! Check the Wi-Fi symbol on the top bar/panel to see if you're connected.

I have space in my schedule; what should I do?

First and foremost- take classes that interest you! Purdue offers a broad spectrum of classes that exist outside of the requirements for your degree. In order to look for all available classes, go to mypurdue.purdue.edu and click on the Registration tab. In the Register for Classes category, click on Look up Classes. In this search tool, choose the term you are looking for and start looking through classes that might interest you.

Need suggestions? Below is a compiled list of fun/interesting classes categorized by topic. Note that course numbers might have changed since this article was written.

Art/Design

AD 242: Ceramics I

Introductory ceramics class. Note there is an extra fee for this class.

HORT 270: Floral Design & Inter Plt Mgmt

Class on flower arrangement and designs with flowers. Note there is an extra fee for this class.

MUS 250: Music Appreciation

No musical background needed- learn more about the fundamentals of music and listen to important musical compositions.

AD 255: Art Appreciation

No artistic background needed- learn more about the fundamentals of art and view art in galleries and in your community.

Sports/Activity

PES 115: Bowling (Indv Dual Mvmt Frm I)

Bowling class where you can bowl in the Purdue Memorial Union! Note there is an extra fee for this class.

Behavioral Science

SOC 100: Intro Sociology

Course covering introductory topics in sociology.

Earth and Planetary Sciences

EAPS 106: Geosciences in the Cinema

This class explores geology and natural disasters in respect to science fiction movies. This class is known to have some of the most interesting/entertaining lectures!

EAPS 104: Oceanography

Introductory course on ocean life, ocean ecosystems, and natural processes in the ocean.

EAPS 100: Planet Earth

Introductory course on Earth’s natural processes.

Outreach

CS 39000SL: MAGIC (Service Learning Outreach)

One credit course where students start programs and initiatives at local high schools in order to introduce girls to computer science. Learn more here!

EPICS

EPICS is a service-learning design program in which teams of students partner with local and global community organizations to address human, community, and environmental needs. To view the different options for EPICS courses, look for courses that start with EPCS. Learn more here!

History

HIST 371: Society & Rock & Roll

Examines post-WWII America and its relation to music, specifically rock and roll.

Honors Courses

There is a misconception that you need to be in the Honors College to take HONR courses. All you need is to have a minimum of a 3.0 GPA in order to enroll in HONR courses, check with your primary advisor about how to sign up for HONR courses. There are some (i.e. HONR 19901 and HONR 19902 that are restricted to first-year honors students).

HONR 29900: Visiting Scholars Seminar

One credit course where students attend events (currently virtual due to COVID-19) with visiting scholars and engage with their work. Every semester, the Honors College hosts a range of visitors from across disciplines.

HONR 29900: Honors College Study Away Programs

Study Away programs are a great way to learn about different communities, cultures, and socio-economic and technical issues in a variety of settings. They are offered during October break, spring break, Maymesters, and over the summer. Study Away programs are a great way to gain some experience abroad in a busy schedule. Some Study Away programs may also be a great way to fulfill your Great Issues requirement, check with your primary advisor about which ones. Learn more here!

Grade Options

Want to take a course you’re interested in but don’t want it to count towards your GPA? Students also have the opportunity to change the grade mode for some classes to Pass/No Pass. In this grade mode, your final grade will be either P (Pass) or NP (No Pass). This grade will not impact your GPA. Note that if you change a grade mode for a certain class, this class will not count toward your degree requirements even if you get a P. The amount of credits of a P/NP class, however, counts towards your overall credit rank- for example, if you’re taking five classes that are each three credits and one class has the P/NP grade mode, you are still a 15 credit student. To fully understand if you can change a course to P/NP and how it will impact your progression in your degree, discuss this option more with your advisor.

Introduction

The Student Wiki is designed to be a source of information that is useful for the Purdue CS/DS community. We encourage anyone to create a new article for the Wiki or edit a preexisting article. We only ask that new articles are tangentially useful to the CS/DS community. We are using GitHub as the means of managing edits to the Student Wiki. Therefore, to contribute to the Student Wiki, you must have a GitHub account

Create a New Article

Step 1

First, you need to fork the purdueusb.com website repository. This can be done by going to the GitHub repository page, and click the "Fork" button on the top right.

Step 2

Once you are in your fork of the Purdue USB website repository, navigate to the _wiki directory.

Step 3

Next, click "Add file" on the top right, then click "Create new file".

Step 4

From here you are going to create a Markdown file for your article. If you are not familiar with Markdown, please read through this guide.

The name of your Markdown file's name should be no more that 3 words long, with dashes (-) separating the words. The file should always end in the .md file extension. The filename will be the URL slug, so lawson-fob.md becomes /wiki/lawson-fob.

To maintain format consistency, please do not use h1 (#) or h2 (##) headings.

You can also use emojis seen on this cheat sheet! :bangbang:

The beginning of your Markdown file should begin with "front matter." This is metadata that is used by Jekyll to better organize your article. This is an example of front matter.

---
title:  "Contribute to the Wiki"
description: "Add or edit an article on the Student Wiki"
author: Noah Alderton
date:   2020-10-28 12:00:00 -0400
categories: campus
---

• title: Title of the article
• description: Describe what the article is about. Keep this down to one sentence.
• author: List of author names exactly as they appear in membership data files.
• date: Date of most recent edit
• categories: Category this fits the article, like technical or campus. Multiple categories can be included, as long as they are comma separated and between square brackets.

A note about images: Please only use images hosted by USB - not from an outside source. In addition, use descriptive and readable captions for wiki images, as they will be displayed to the user and read aloud via screen readers. Add images to a directory in /assets/images/wiki/<article-name>. From there, will be able to reference local images in your article like so:

![Community Hub Homepage](/assets/images/wiki/connect-vpn/step1.png)

Step 5

Once you are finished typing up your article, add a commit message, and click the green "Commit new file" button on the bottom.

Step 6

Now, you need to go to the "Pull requests" tab, and click the green "New pull request" button. Here, you are going to create a new pull request that merges your fork of the website into the Purdue-CSUSB/purdueusb.com repo.

Edit Existing Article

Step 1

Navigate to the _wiki directory and open the Markdown file that you wish to edit.

Step 2

Click the edit button on the top right. This will make a fork of the website repository. From here you can the desired changes to the wiki article. If you are not familiar with Markdown, please read through [this guide]. Also, please do not use h1 (#) or h2 (##) headings in an effort to maintain format consistency across the articles.

Step 3

Once you are finished making those edits, add a commit message, and click the green "Commit changes" button on the bottom.

Step 4

Now, you need to go to the "Pull requests" tab, and click the green "New pull request" button. Here, you are going to create a new pull request that merges your fork of the website into the Purdue-CSUSB/purdueusb.com repo.

Our wiki is built with tools make your searches more powerful and precise. You can use any combination of the operators explained below:

Wildcards

Wildcards let you match any text and are represented by asterisks (*). For example, C* S* matches words starting with C or S. Together they match phrases like Computer Science or Canadian Studies, among other things.

Fields

Fields relate to meta-information about our articles, such as the date or author. You can use them to search only titles, for example, instead of searching the entire wiki. Search for this article with title:optimize.

Available fields: title, description, content, author, category, and date.

Boosts

You can use boosts to prioritize certain search terms over others. For example, foo^10 bar tells the website you're 10x more interested in the search term foo than bar. Articles containing foo would then be higher in the search results.

Fuzzy Matches

Fuzzy matching allows for some grace if you misspell a term or are off by a few letters. For example, foo~1 matches anything 1 letter away from foo, like boo or food. It will not match words like boot because it has a difference of two letters.

Term Presence

Term presence allows you to explicitly include or exclude phrases in your search query with the symbols + and -, respectively. For example, +foo -bar baz matches only content with foo and without bar, that also may contain baz.

By default, a result comes back if any word separated by a space matches some content. This is a limitation of the code our website uses. Searching for +author:Purdue Pete is seen as two separate terms, +author:Purdue and Pete.

Nothing's perfect.

Bringing It All Together

You can make your search as simple or as complex as you'd like. As an example, if I wanted to search for meta-articles I've authored in June, containing the mis-spelled phrase crakatoa, I could type category:meta +author:Zach +Bryant +date:June -crakatoa~1. Except at this time, my only article contains the phrase krakatoa.

Thank you for coming to my TED talk.

Below are links you can use to sync the Purdue Computer Science calendars using your preferred calendar app. The CS department switched to Google Calendar just for you! :tada:

Note: We recommend subsribing to the Google Calendar link. Downloadable calendars do not update automatically.

Departmental events, such as Town Hall or career workshops:

• Google Calendar Embed
• Webcal
• iCalendar (.ics)

Corporate events, such as recruiting days:

• Google Calendar Embed
• Webcal
• iCalendar (.ics)

CS seminars & colloquiums:

• Google Calendar Embed
• Webcal
• iCalendar (.ics)

Student organization events:

• Google Calendar Embed
• Webcal
• iCalendar (.ics)

Introduction

A Virtual Private Networking (VPN) is a method that allows users to securely access an organization's internal network resources. By using Purdue's VPN service, you can access resources that are only available on campus anywhere, e.g. printing to any campus printer, remotely accessing Purdue's servers/UNIX machines (like mc19.cs.purdue.edu) through remote desktop, etc.

This tutorial will show you how to connect to Purdue's VPN using Cisco AnyConnect.

Step 1

To download Cisco AnyConnect, go to the Purdue Community Hub. After login in, you would want to go to "Antivirus and Security Software".

Step 2

Select Cisco AnyConnect for Personally Owned Computers and select the appropriate settings for your computer. After adding the software to your cart, download Cisco AnyConnect.

Step 3

Once you finished installing Cisco AnyConnect, open it up. You will see that Cisco AnyConnect is ready to connect to the VPN server: webvpn.purdue.edu.

There are a couple options you can choose. Due to COVID-19, more people are utilizing Purdue's VPN services. Purdue has created another VPN server: webvpn2.purdue.edu/ for people to connect to. Whichever VPN server you choose to connect to will work.

Step 4

After you click "Connect", a prompt for login in will pop up. Your username is your Purdue username and the password is your BoilerKey password (pin,push).

Step 5

You should be able to connect to Purdue's VPN server! A pop-up will notify you that you are connected. Another way to tell is to check is on the task/menu bar. From the picture below, the lock symbol signifies that you are connected.

Step 6

After using Purdue's VPN, you want to disconnect. On Windows, right click on the Cisco AnyConnect icon, and click "Disconnect". On Mac, to disconnect, click on the Cisco AnyConnect icon from the menu bar and select "Disconnect".

As a CS student, you can get a keyfob from the Lawson mailroom which will give you after-hours/weekend access to the Lawson building, as well as the student activities center in HAAS G072.

Getting a New Keyfob

To get a keyfob all you need to do is email cs-workstudy@purdue.edu When your request has been fulfilled you will receive an email informing you that your fob can be picked up at the mailroom in Lawson.Here's a template that might be helpful:

Subject: Lawson Keyfob

To whom it may concern,

I am a computer science student enrolled in [CS courses here]. I would like a keyfob to access the Lawson building after-hours.

Thank you, [Your name]

Renewing an Existing Keyfob

Keyfob access expires every semester. If you don't renew your keyfob, you won't be able to get into the building or offices without renewing. To renew your keyfob, simply email cs-workstudy@purdue.edu again and request that your fob be renewed. In the email, tell them new CS courses you are enrolled in.

Introduction

Sometimes there comes a need where you need to transfer a files between your personal computer and one of Purdue's servers (like data.cs.purdue.edu). The tutorial will show you how to transfer files between your computer and a remote server (and vice versa) using SCP via command line and FileZilla. These methods will work on Windows, Mac, and Linux.

Solution 1: Command Line

Step 1

On Windows open “Windows PowerShell.” On Mac or Linux, open your respective Terminal.

Step 2

In order to transfer your files, we are going to use SCP. SCP works the same regardless of operating system. The SCP program takes the following parameters:

scp <source_directory> <destination_directory>

For our purposes of transferring homework from data, we are going to use the following command:

scp <purdue_username>@initiatives.cs.purdue.edu:<homework_directory> <personal_machine_directory>

For example, if I wanted to transfer my hw2.c file to my current directory on my PC, I would run:

scp nalderto@initiatives.cs.purdue.edu:~/cs240/hw2/hw2.c .

Step 3

If everything ran properly, you should be able to access your homework on your personal machine. Keep in mind that this is a copy of your homework, so any changes you make on your personal machine will not be reflected on data and vice versa. If we want to transfer a file from our personal machine to data, we would need to run SCP again, flipping the source and destination directories.

For example, if I wanted to transfer my hw2.c file from my personal machine to data, I would run:

scp hw2.c nalderto@initiatives.cs.purdue.edu:~/cs240/hw2/

Solution 2: FileZilla

Step 1

If you are not comfortable with the command line, there are several graphical user interface programs that are available which provide the same functionality. In this tutorial we are covering FileZilla, as it is compatible with Windows, Mac, and Linux.

You can download FileZilla here.

Step 2

Once you have finished installing FileZilla, open it up. On the top, there should be 4 input boxes. Put in the following information:

• Host: sftp://data.cs.purdue.edu
• Username: Purdue Username
• Password: Purdue Career Account Password (same password used to SSH into data)
• Port: 22

Step 3

Once the appropriate information is entered, click “Quickconnect”. A dialog might appear about trusting the connect. Go ahead and trust the connection.

Step 4

You should now be connected to data! Your data filesystem is on the right part of the screen, while your personal computer’s files are on the left. You can drag and drop the files between the machines as you wish!

There are a few different opportunities to rent equipment for both classwork and personal use. The Department of Computer Science allows CS/DS students to rent various equipment online.

The following devices are available to rent for 1 week at a time:

• SenseHat
• Raspberry Pi 3
• Particle Photon
• Pebble Smartwatch
• LittleBits
• Myo
• LeapMotion
• Parrot Rolling Spider MiniDrone
• Oculus Rift DK2
• HoloLens

Additionally, Purdue Libraries has cameras, camcorders, tripods, and hard drives available to rent for 3 days.

To learn more, see the Purdue Libraries Equipment page.

What is USB?

Established in 1999, The Computer Science Undergraduate Student Board is dedicated to improving the student experience within Computer and Data Sciences at Purdue- whether by managing CS193, hosting forums for student advocacy, or maintaining a database of undergrad-tailored resources, USB is continually creating initiatives that will uphold our values. Check out our initiatives page to see what we’re up to now!

What do USB members do?

That will be completely up to you! USB prides itself in being driven by student-led initiatives- if a board member has an idea and a plan, they are encouraged to take lead. Initiatives can be small or large, and members are given flexibility to be able to move from project to project if it’s in their best interest.

What are the responsibilities of USB members?

All USB members are expected to be working on at least one initiative- this can mean being the member of an initiative team or being the lead of an initiative with heightened responsibility. Along with work on your initiatives, USB has a mandatory hour-long weekly meeting where initiative leads can report their progress and members can discuss any new ideas or suggestions.

How to Join

USB opens applications early December and keeps them open until the beginning of Spring semester. If you follow us on social media (such as our Facebook or Instagram), you’ll be the first to know when it releases!

What’s the application process?

Our interview can be split up into 2 main parts.

-Our general application is released early December and stays open until the beginning of Spring semester. It is made up of personal and behavioral questions about yourself. We’re not looking for the longest response (although details, if important, can definitely add to your application)- we want to see what you’re passionate about. If possible, give us a specific situation that or personal experience relates to the question.

-Final interview offers will be sent out within the next two weeks. After scheduling your interview, we will invite you to either an in-person or virtual interview. You will be able to sit with two interviewers and answer some more personal and behavioral questions. Again, we want to know about you- sharing personal, specific experiences will allow us to get to know you better! During the second half of your interview you will be given a ‘situation’ question where you’re encouraged to share an idea or initiative you have for the CS department and how you would lead it.

Traditionally, we have had a third optional event with all candidates that made it to the final round of interviews- in the past, we have invited candidates to bowl with us and have dinner. The purpose of this optional meeting is to be able to meet all candidates in a relaxed setting and to get to know you more personally. Since this event is optional, we do not use it as a definitive way to consider candidates, but it (if anything) gives an excuse to have some fun and free food!

What are we looking for?

USB cares about diversity. The computer science department heavily lacks diversity and we believe that the best way for a student organization to address this is to amplify and elevate the voice of minority groups in tech. We want our board to be representative of the diverse community we are trying to build.

USB is also looking for passion and great ideas for the CS department. Initiatives are completely maintained and created by USB members, so we want to find individuals who truly care about the work they will do with us. We love to talk with candidates who have genuine interest or a specific experience that is driving their idea- maybe a love for teaching that has given them an idea for a mentorship initiative, or an experience in class that made them realize there was an easier way to hold PSOs.

I believe in what USB is doing but do not want to become a member. Can I still make changes within the CS department?

You definitely can! While USB provides existing relationships with faculty and a network of supportive members who can help start your initiative, it is by no means the only way to do so. If you have an idea for the CS department, take initiative and contact your professors, faculty members, and your peers. Conduct some research and form a plan- change can absolutely come from an individual. And USB is more than willing to help- if you feel stuck, don't hesitate to come to our scheduled office hours or send us an email about your idea and we will share any helpful resources we have!