2. What is Revision Control?
• Keeps track of changes over time
• Allows you to go back in time
• Helps prevent code from “disappearing”
3. Revision Control Systems
• cp –R source_dir source_dir-2013.02.20.12.18.52
• Mark Rochkind creates Source Code Control System
(SCCS) in 1972
• Walter Tichy releases Revision Control System (RCS)
in 1982 (still actively maintained)
• CVS introduced in 1986 (handles editing multiple
files at once)
• Commercial systems: ClearCase, VSS and Perforce
4. Revision Control Systems (cont)
• Subversion (SVN) came out in 2000. Designed to be
mostly compatible with existing CVS projects.
– Offers atomic commits (CVS did not)
– Keeps track of file renames and moves
– Branching / Tagging is expensive (copies all files)
– Tags are modifiable
5. Revision Control Systems (cont)
• Git introduced in 2005
– Linux kernel used BitKeeper (commercial
software) because it was free for OSS
– Bitkeeper started charging, so Linus Torvalds
wrote a compatible program (Git)
• Mercurial (similar to Git) was also created
because of the BitKeeper license change
6. Features of Git
• Git has a strong emphasis on non-linear
development
• Branching and merging is easy
• Auditing of history
– If the code in a commit changes, the SHA-1 changes
– Once published, it prevents history changes without
people noticing
• Distributed Development is the #1 selling point
7. Git 101
• Setup central “blessed” repository
– Each developer downloads a copy
– Developer can do local development without
affecting other developers
• Branching is cheap
– git checkout -b branch_name
8. Getting started with Git
• mkdir test_app
• cd test_app
• vi hello_world.rb
#!/usr/bin/env ruby
puts “Hello World”
• git init .
• git status
• git add hello_world.rb
• git commit –m ‘Added hello_world.rb’
9. Github
• Github.com is a website that hosts Git repos
• Allows you to share your code with others
• Easy Forking / Cloning of existing repos
• Provides an easy to use website for hosting
your software projects
10. Create New Repo on Github
• Visit https://github.com
– Login if necessary
• Click New Repository
• Enter repository name, description
• Click Create repository
• Follow directions
11. Additional Hands on Training
• Tonight from 6:30 to 8:30pm
• Bring a laptop with Git installed
• Signup for a Github.com account
• Hands on instructor led tutorial
– TAs will be available to assist
• http://www.meetup.com/DaVinci-
Coders/events/104098422/
