Git is a distributed version control system that was created by Linus Torvalds to be fast, support large projects, and have an active development history. Everything in Git is stored locally, there is no need for a centralized server, and files are tracked as objects with metadata. Common Git commands include git clone, git add, git commit, git branch, git checkout, and git merge or git rebase to integrate work. Visualization tools help understand the commit graph structure.

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Git - the stupid content tracker
Henrik Austad
UNINETT Sigma A/S
15. Oct 2009

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about:henrik
Henrik Austad
MSc Engineering Cybernetics
UNINETT Sigma A/S & NDGF
System Developer

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Background - In the beginning ... was patch
• Initially written by Linus Torvalds to replace BitKeeper
• First “working” version: April 18th 2005
• git v1.0 December 21th 2005
• Written for
• Speed
• Track changes
• Large projects with active history

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Contenders
• Bazaar (bzr)
• Darcs
• Mercurial (hg)
• svk

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What does “distributed” mean?
• Everything is local.

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What does “distributed” mean?
• Everything is local.
• No “need” for a centralized repository.

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What does “distributed” mean?
• Everything is local.
• No “need” for a centralized repository.
• Disk is cheap - network is not.

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What does “distributed” mean?
• Everything is local.
• No “need” for a centralized repository.
• Disk is cheap - network is not.
• Lower threshold for new developers, you don’t need special
access to the repository to get started.

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git objects
• type
• blob
• tree
• commit
• tag
• size
• content

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git objects
• type
• blob
• tree
• commit
• tag
• size
• content
Figure: git example.credits: Scott Chacon

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Normal commands
• git clone repo dest
• git init

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Normal commands
• git status
• git log start..end
• git branch name of new branch start commit
• git checkout branchname

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Normal commands
• git add path/to/file
• git commit -s -m “short commit msg”
• git rebase -i commit
• git cherry-pick commit

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Normal commands
• git remote
• git push
• git pull
• git fetch

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Normal commands
• git tag
• git diff
• git format-patch
• git am

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Normal commands
• git config –global user.name “Henrik Austad”
• git config –global user.email “henrik@austad.us”
• git config user.email “local@project.mail”
• git config push.default current

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git merge vs. git rebase
An example, 3 branches, commits done in alphabetical order

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git merge vs. git rebase
Merge F and D giving H, then H and G giving I

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git merge vs. git rebase
Rebase F onto D, rewriting F to F’, then C-F’ onto G

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Hooks - it’s a kind of magic
See .git/hooks/
• pre-commit
• post-update

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Visualization
• git log –graph
• git-gui
• gitk
• qgit

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Questions?
http://git-scm.com/
mailto:git@vger.kernel.org
http://www.kernel.org/pub/software/scm/git/docs/
everyday.html