Git Branch
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The document discusses Git branching workflows. It explains that branching allows developers to work independently on different versions of code without affecting the main/stable version. The key points covered include how to create, checkout, merge and delete branches. It also discusses the differences between merging and rebasing branches, and provides examples of common Git workflows like the integration manager model and dictator and lieutenants model. Finally, it summarizes the typical GitHub pull request workflow.
![Create and checkout a Branch
• Create a new branch
– git branch [name]
• Checkout a branch (move HEAD to a branch)
– git checkout [name]
• Create and checkout a new branch
– git checkout –b [name]
Ubiquitous Computing and Ambient Networking Laboratory Page : 7](https://image.slidesharecdn.com/04gitbranch-171123120043/85/Git-Branch-7-320.jpg)
![Delete a Branch
• Delete a branch
– # git branch –d [name]
– Actually, this just deletes the branch pointer.
Ubiquitous Computing and Ambient Networking Laboratory Page : 12](https://image.slidesharecdn.com/04gitbranch-171123120043/85/Git-Branch-12-320.jpg)
Git Branch
- 1. Git Branch Wei-Tsung Su (蘇維宗) ellington.su@gmail.com 11/23/2017 (Ver. 1.0) Ubiquitous Computing and Ambient Networking Laboratory Page : 1
- 2. Change Log Date Ver. Authors Description 11/23/2017 V1.0 Wei-Tsung Su Baseline Ubiquitous Computing and Ambient Networking Laboratory 2
- 3. Reference • Scott Chacon, Git Pro, Jul. 29, 2009. Available: http://git-scm.com/book Ubiquitous Computing and Ambient Networking Laboratory Page : 3
- 4. Agenda • What is branch? • Why using branch? • Operations – Create and checkout a branch – Merge two branches – Remove conflicts – Rebase branch on the other one – Delete a branch • Git Workflow • GitHub Workflow • Demonstration Ubiquitous Computing and Ambient Networking Laboratory Page : 4
- 5. What is branch? • Branching model is referred as a killer feature of Git. • Git commit data structure – Point master is a branch pointing to a specific snapshot. – Point HEAD is pointing to current working branch. Ubiquitous Computing and Ambient Networking Laboratory Page : 5 commit tree Snapshot A blob File 3 blob File 2 blob File 1 commit tree Snapshot B commit tree Snapshot C master HEAD blob File 1 (modified) Compressed
- 6. Why using branch? • Case 1 – Issue fixing without polluting stable version. – Merge is required after issue has been fixed. • Case 2 – Creating different product lines for various platforms, customers, etc. – Merge may or may not be required. • Others Ubiquitous Computing and Ambient Networking Laboratory Page : 6
- 7. Create and checkout a Branch • Create a new branch – git branch [name] • Checkout a branch (move HEAD to a branch) – git checkout [name] • Create and checkout a new branch – git checkout –b [name] Ubiquitous Computing and Ambient Networking Laboratory Page : 7
- 8. Merge two branches • Assume merge branch B into branch A – # git checkout A – # git merge B • However, there may be conflicts while merging two branches. That is, the same part of the file is changed differently in two branches. Ubiquitous Computing and Ambient Networking Laboratory Page : 8
- 9. Remove Conflict • Step 1. check the files which have conflicts <<<<<<< HEAD:index.html <div id="footer">contact : email.support@github.com</div> ======= <div id="footer"> please contact us at support@github.com </div> >>>>>>> iss53:index.html • Step 2. remove conflicts manually • Step 3. commit changes – # git commit Ubiquitous Computing and Ambient Networking Laboratory Page : 9
- 10. Rebase branch on the other one • Assume rebase branch B on branch A – # git checkout B – # git rebase A • Similarly, remove conflicts if rebasing a branch on the other one. – Abort rebasing • # git rebase --abort – Continue rebasing – # git add . – # git rebase --continue – # git checkout A – # git merge B • Note – DO NOT rebase the commits that are pushed to public repository. Ubiquitous Computing and Ambient Networking Laboratory Page : 10
- 11. Merge v.s. Rebase Ubiquitous Computing and Ambient Networking Laboratory Page : 11 S1 S3 S2 A B Before merge or rebase S1 S3 S2 A S4 B After merging A and B S1 S3 A B S2' After rebasing B on A
- 12. Delete a Branch • Delete a branch – # git branch –d [name] – Actually, this just deletes the branch pointer. Ubiquitous Computing and Ambient Networking Laboratory Page : 12
- 13. Git Workflow • Integration-Manager workflow Ubiquitous Computing and Ambient Networking Laboratory Page : 13 Forked repositoryForked repository Original repository Integration Manager Forked repositories Contributors 1. clone 2. create branch 3. make changes on branch 4. pull request 5. merge
- 14. Git Workflow (con't) • Dictator and Lieutenants workflow – Generally used by huge projects, such as Linux kernel Ubiquitous Computing and Ambient Networking Laboratory Page : 14 Lieutenant repositories Lieutenant repositoriesOriginal repository Dictator Lieutenant repositories Benevolent dictators 1. clone 2. create branch 3. make changes on branches 4. pull request 5. merge Lieutenant repositories Lieutenant repositoriesForked repositories Contributors B. create branch C. make changes on branches D. rebase changes to master A. clone F. merge E. pull request
- 15. GitHub Workflow • GitHub is an example of Git workflow based on pull request. • In typical, GitHub workflow has the following steps – Fork original project – Create a topic branch on forked project – Make changes on this topic branch – Send a pull request to original project – Discuss and make changes if necessary – Owner of original project decides to merge or close this pull request. Ubiquitous Computing and Ambient Networking Laboratory Page : 15
- 16. Q & A Ubiquitous Computing and Ambient Networking Laboratory Page : 16