• Haïkel Guémar
• Fedora Packager
• Senior Engineer @ SysFera
• twitter: @hguemar

• Background
• Under the hood
• Workflows
• Use
• GitHub
• The End Of Hypnosis

* from Geek Hero Comic CC-By-NC-SA 3.0

• manages and tracks different version of content
• allow collaborative work

• 1972: SCSS
• 1982: RCS
• 1986: CVS
• 2001: BitKeeper, GNU Arch
• 2002: SVN, Darcs
• 2003: Monotone
• 2005: Git, Mercurial
• 2007: Bazaar

Linus Torvalds, Linux Kernel Creator

I'm an egotistical bastard, and I name all my projects after myself. First 'Linux', now 'git'.

• April, 3rd 2005: beginning of development
• April, 6th 2005: first release
• April, 7th 2005: git development is self-hosted
• July, 26th 2005: Junio Hamano is appointed as the new maintainer

• Linux kernel hackers BitKeeper licenses were revoked
• No FLOSS alternatives in many aspects

• CVS: "There is no way to make CVS right"
• Facilitates (highly) distributed workflow that scales
• Maintains data integrity
• Performant enough for kernel development
• Design inspired by File Systems

A SCM that is

• distributed
• performant
• no forced workflow (Bring Your Own Workflow)
• robust
• cheap branches
• history rewrite
• offline work

a content manager

stored as an objects acyclic graph

objects accessible through references

• porcelain (frontend)
• plumbing (backend)

There were only plumbing commmands

Many frontends were made available (cogito, eg)

Understanding git internals is the key for efficient use

Remember that git is a content manager

Is a

• database that contain a project whole history
• complete copy of a project

Built upon two data structures

• object store
• index

Every object is identified by a SHA-1

Which garantees unicity up to 2^160 objects

• blobs
• trees
• commits
• tags

Also know as staging area

• Managed by git
• Managed by users

They're just references too, that's why you get cheap branching !

tags !

• No time based vision
• Commits are linked to each other in a graph
• Objects are immutable
• but the graph itself is mutable
• Content is accessed through references

• No forced workflow
• Forks are encouraged

• No more commit access rights
• Disagree ? Just fork it !

No more assymetry between maintainer(s) and the others

37 main

14 manipulations

16 interrogations

9 interactions

init/merge/clone

fetch/commit/push/branch

checkout/add/log/diff

Tell git to ignore files:

• by repository: using local .gitignore file

• globally:

  !bash git config --global core.excludesfile ~/.gitignore

st    = status -sb
ci    = commit
co    = checkout
br    = branch -a
rb    = rebase
sb    = show-branch
unadd = rm -r --cached
wd    = diff --word-diff
ws    = show --word-diff
purr  = pull --rebase
amend = commit --amend

ref^ = ref parent
ref~2 = ref grand-parent

... and make it simpler with rebasing !

... let's rewrite history

allows you to:

• edit commits
• merge/slice commits
• remove commits
• reorder commits

Social Coding Platform

• Fork & Pull Request
• Encourage collaborative work through gamification

• Ding Dong, I have commits to share with you
• discussion around your modification
• merge (or get rejected)

https://github.com/blog/1124-how-we-use-pull-requests-to-build-github

• Improve drastically code quality
• Lower defect rates
• Encourage communication
• Sets a common ground for the team (coding standards, architecture, etc.)

• Official site: http://git-scm.com/
• Pro-Git: http://git-scm.com/book/
• O'Reilly: "Version Control with Git"