Lab session 1 Git & Github

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Emery Townsend
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1 Lab session 1 Git & Github

2 Administration Course personnel: Lecturer - Refael Dakar, currentintec@gmail.com TA - Avi Hayoun, hayounav@cs.bgu.ac.il Office hours - Tuesdays, 109/37 (might change) Course website: Lab sessions: Sundays, 003/92 Mandatory attendance *

3 Syllabus Modern web technologies HTML Abstract away HTML with templating CSS CSS on steroids (LESS, SASS) JS Abstraction/Utility libraries (JQuery, BackboneJS, etc.) Server side (NodeJS) OSS Good software engineering practices VCS Style guides UX Async/Event-driven

4 Today VCS What is it? Why use it? Overview and history Git History Pros and Cons Github Interactive Exercise

5 Version Control Systems What is version control? A system that records changes to a file or set of files over time so that you can recall specific versions later. We will use VCS primarily for source code management Any type of file on a computer can be placed under version control.

6 Version Control Systems Why should you care? A VCS allows you to: Revert files (even the entire project) back to a previous state Review changes made over time See who last modified something that might be causing a problem And more Using a VCS also means that if you screw things up or lose files, you can generally recover easily. In addition, you get all this for very little overhead.

7 History of VCS Once upon a time, there was no VC software People used to just copy files around to back up and maintain older versions of their work. Most people still do. Pros: Simple Cons: Error prone: Easy to forget which directory you re in and accidentally write to the wrong file Copy over files you don t mean to

8 Local VCS In 1972, Marc Rochkind, then an employee at Bell Labs, developed the first Local VCS: SCCS. Local VCSs had a simple database that kept all the changes to files under revision control. Pros: There is now version control!!! Cons: No collaboration

Centralized VCS What people were still missing was the ability to work together on the same project, while still enjoying the benefits of version control.

9 Centralized VCS What people were still missing was the ability to work together on the same project, while still enjoying the benefits of version control. Enter Centralized Version Control Systems (CVCSs): The project is hosted on a single server Clients connect and check out files Pros: Collaboration Cons: Single point of failure Admin overhead

10 Distributed VCS This is where Distributed Version Control Systems (DVCSs) step in. Clients don t just check out the latest snapshot of the files, they fully mirror the repository. If any server dies, any of the client repositories can be copied back up to the server to restore it. Every checkout is really a full backup.

11 Git In the beginning, the Linux Kernel project was a mess - changes to the software were passed around as patches and archived files. In 2002, the Linux kernel project began using a proprietary DVCS system called BitKeeper, but in 2005 the tool s free-of-charge status was revoked. Linus decided to develop a new tool based on some of the lessons learned while using BitKeeper. Some of the goals of the new system were: Speed Simple design Strong support for non-linear development (thousands of parallel branches) Fully distributed Able to handle large projects like the Linux kernel efficiently (speed and data size)

12 Git basics So, what is Git in a nutshell? Snapshots, Not Differences Nearly Every Operation Is Local Git Has Integrity Git Generally Only Adds Data The Three States committed modified staged

13 Git - Demo

14 Github GitHub is a web-based hosting service for software development projects that use the Git revision control system. GitHub offers both paid plans for private repositories, and free accounts for open source projects. The site was launched in You will get free private repositories for the duration of the course

15 Exercise

Introduction to Version Control with Git

Introduction to Version Control with Git Dark Cosmology Centre Niels Bohr Institute License All images adapted from Pro Git by Scott Chacon and released under license Creative Commons BY-NC-SA 3.0. See