distributed version control with git a brief...

Oscar Nierstrasz

Distributed version control with git — a brief introduction

Thursday, September 15, 11

Why git?


Bob


Bob Carol


Bob Carol

TedAlice


Bob Carol

TedAlice

A recipe for disaster!Thursday, September 15, 11

The git object model


blob

A “blob” is content under version control (a file)


You can have trees of blobs(directories of files)

blobblob

tree

treeblob


A “commit” is a tree of blobs(a set of changes)

blob

commit

blob

tree

treeblob


Most commits modify (or merge) earlier

commitscommit

blob

tree

blob

commit

blob

tree

treeblob


You can “tag” an interesting commit

commit

blob

tree

tag

blob

commit

blob

tree

treeblob


A graph of commits may belong to a branch

commit

blob

tree

tag

branch

blob

commit

blob

tree

treeblob


commit

blob

tree

tag

HEAD

branch

blob

commit

blob

tree

treeblob

“HEAD “is the current branch


Let’s focus on commits and branches

commit

HEAD

branch

commit


Basic git


mkdir repocd repogit init

Create a git repo

C0

HEAD

master


git add …

Tell git to “stage” changes

C0

HEAD

master


C1

HEAD

master

git commit …

Commit your changes

C0


Collaborating


Public repoLocal repo

John Jane

Local repo

master

C1

C0



John Jane

Local repo

git clone …

git clone …

mastermastermaster

C1

C0

C1

C0

C1

C0



John Jane

Local repo

git add …git commit …

git add …git commit …

mastermastermaster

C0

C1

C0

C1

C1

C0

C2 C3



John Jane

Local repo

git pull

(nothing new to pull)

mastermastermaster

C0

C2 C3

C1

C0

C1

C1

C0



John Jane

Local repo

git push

mastermastermaster

C0

C2

C1

C0

C3

C1

C0

C2

C1



John Jane

Local repo

git fetch

mastermastermaster

C0

C2 C2

C1

C0

C3

C1

C0

C2

C1



John Jane

Local repo

git merge

NB: git pull = fetch + merge

C3

master

C1

C0

C2

mastermaster

C0

C2 C2

C1

C0

C1

C4



John Jane

Local repo

git push

C3

master

C1

C0

C2

master

C1

C0

C2

master

C0

C2

C3C1

C4C4



John Jane

Local repo

git pull

C3

master

C1

C0

C2C3

master

C1

C0

C2C3

master

C1

C0

C2

C4 C4C4


Branching and merging


“origin” refers to the remote repo

C1

master

C0

origin/master

HEAD


…git commit …

C1

master

C0

origin/master

HEAD

C2


git branch tryout

C1

master

C0

C2

tryout

origin/master

HEAD


git checkout tryout

NB: git checkout –b … = branch + checkout

C1

master

C0

C2

tryout

origin/master

HEAD


git commit …

C1

master

C0

C2

tryout

origin/master

HEAD

C3


git fetch origin

C1

master

C0

C2

tryout

C3

origin/idea

origin/master

HEAD

C4

C5

C6


git merge origin/master origin/idea

C1

master

C0

C2

tryout

C3

C4

C5

C6

origin/idea

origin/master

HEAD

C7


git checkout master

C1

master

C0

C2

tryoutHEAD

C3

C4

C5

C6

origin/idea

C7

origin/master


git merge

C1

master

C0

C2

tryoutHEAD

C3

C4

C5

C6

origin/idea

C7

origin/master

C8


C1

master

origin/master

C0

C2

tryout

git push

HEAD

C3

C4

C5

C6

origin/idea

C8C7


More to git


More to git …

> Merging and mergetool> Squashing commits when merging> Resolving conflicts> User authentication with ssh> gitx and other graphical tools> git configure — remembering your name> git remote — multiple remote repos> github — an open source public repo> …

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Resources

http://book.git-scm.com/index.htmlhttp://git-scm.com/

https://github.com/

http://www.slideshare.net/chacon/getting-git http://oreilly.com/


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