git basics! Marvin  Killing   Co-­‐founder,  PlaytestCloud   Git  Aficionados,  2013-­‐12-­‐13   

Blobs! Trees! Commits! 

If you change anything about an object, it’s not the same object anymore.! 
 It becomes a new object.! SHA1! a3768903ca03f7cccb3c6b6f474f88f8e9a3bb5b 

commit! hello.txt A3768903ca03f7cc... 97b49d4c943e3715fe30f141cc6f27a8548cee0e a3768903ca03f7cccb3c6b6f474f88f8e9a3bb5b Hello World tree 97b49d4c943e3715f...   initial msg: a3768903ca03f7cccb3c6b6f474f88f8e9a3bb5b Tree! Blob! 

parents! initial msg: commit 2 msg: commit 3 msg: 

a3768903 initial msg: commit 2 msg: commit 3 msg: master branch! ca03f7cc cb3c6b6d 

commit 2 msg: commit 3 msg: master branch1 initial msg: $ git branch branch1 HEAD 

a5d743   initial msg: commit 2 msg: Feature A msg: master Feature B msg: branch1 HEAD $ git checkout branch1 $ git checkout a5d743 You are in 'detached HEAD' state. You can look around, make experimental changes and commit them, and you can discard any commits you make in this state without impacting any branches by performing another checkout.   

commit 2 msg: Feature A msg: Feature B msg: branch_b merge branch_b msg: master HEAD $ git merge branch_b 

initial msg: commit 2 msg: Feature B msg: branch_b fast-forward! master HEAD $ git merge branch_b 

initial msg: commit 2 msg: commit 3 msg: master HEAD $ git reset --hard HEAD^ a3768903 ca03f7cc cb3c6b6d 

initial msg: commit 2 msg: commit 3 msg: master HEAD $ git reset --hard 

collabo! ration! 

alice commit1 commit2 commit a master bob commit1 commit2 commit a master origin commit1 commit2 commit a master 

alice commit1 commit2 commit a master commit b bob commit1 commit2 commit a master commit1 commit2 commit a master alice$ git push origin master commit b origin 

alice commit1 commit2 commit a master commit b bob commit1 commit2 commit a master origin commit1 commit2 commit a master commit b commit b bob$ git fetch origin/master 

alice commit1 commit2 commit a master commit b bob commit1 commit2 commit a master commit1 commit2 commit a master commit b commit b origin/master bob$ git fetch bob$ git merge origin/master 

git pull git fetch git merge =! +! 

alice commit1 commit2 commit a master bob commit1 commit2 commit a master origin commit1 commit2 commit a master Feature B Feature B Feature A Feature B origin/master merge origin/master Feature A merge origin/master fetch merge origin/master push 6c699cb..04872e1 master -> master 

John  McDonnell:  Git  for  computer  scienEsts    hFp://nyuccl.org/pages/GitTutorial/     resources! ScoF  Chacon:  Pro  Git          hFp://www.git-­‐scm.com/book   LearnGitBranching          hFp://pcoFle.github.io/learnGitBranching/   

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pro features! 

staging area! 

rebase! 

git commit -- amend! 

refspecs! 

cherry-pick! 

add -p! 

aliases! 

git lol! 

shell extensions 

Blob! a3768903ca03f7cccb3c6b6f474f88f8e9a3bb5b Hello World 

Tree! hello.txt A3768903ca03f7cc... 97b49d4c943e3715fe30f141cc6f27a8548cee0e a3768903ca03f7cccb3c6b6f474f88f8e9a3bb5b Hello World 

.gitignore! # Untracked files: # (use "git add ..." to include in what will be committed) # # .DS_Store # config/database.yml # log/