Introduction to distributed version control with git

Size: px

Start display at page:

Download "Introduction to distributed version control with git"

Wilfred Walker
5 years ago
Views:

1 Institut für theoretische Physik TU Clausthal

2 Inhalt 1 Basics Differences to Subversion Translation of commands 2 Config Create and clone States and workflow Remote repos Branching and merging Workflows 3 Advanced topics 4 Administration with Gitolite 5 Helpers 6 Weblinks 7 Conclusion

3 Basics Differences to Subversion Differences to Subversion: conceptual fully distributed data seen as snapshots, not differences (Subversion, Bazaar,...) optimized for branching and merging

4 Basics Differences to Subversion Differences to Subversion: practical git only adds data git uses hashes (SHA1) a lot (no revision numbers) only one.git directory

5 Basics Differences to Subversion Differences to Subversion: practical git only adds data git uses hashes (SHA1) a lot (no revision numbers) only one.git directory (nearly) every operation is local/offline multiple remote repos (origins) possible git clones whole repository including history clones are full repository backups

6 Basics Differences to Subversion Differences to Subversion: practical git only adds data git uses hashes (SHA1) a lot (no revision numbers) only one.git directory (nearly) every operation is local/offline multiple remote repos (origins) possible git clones whole repository including history clones are full repository backups branching and merging is easy and efficient every branch has its own history branching allows more efficient workflows

7 Basics Translation of commands task git svn create a repo git init svnadmin create repo git add. svn import file://repo git commit get a repo git clone URL svn checkout URL git pull svn update status/log git status/log svn status/log restore a file git checkout file svn revert file add/rm/mv file git add/rm/mv file svn add/rm/mv file commit changes git commit -a svn commit share changes git push list branches git branch svn list URL/branches/ create branch git branch BRANCH svn copy URL/trunk... git checkout BRANCH svn switch URL/branches/BRANCH merge branches git merge BRANCH svn merge -r 20:HEAD URL/branches/B

8 Basics Revision numbers Revision numbers: use tags or count commits in specific branch: git rev-list BRANCH wc -l git rev-list --reverse BRANCH grep -n HASH cut -d: -f1 or abbreviated hashes: git show --abbrev-commit BRANCH grep commit sed -e s/commit //

9 Basics nomenclature nomenclature: non-bare and bare local and remote

10 Basics nomenclature nomenclature: non-bare and bare local and remote a nonbare git project contains working copy repository (.git-directory) links to a number of bare remote reposiories (origins)

11 Config Getting started: git config --global user.name "Your Name Comes Here" git config --global user. name and mail in every commit-message

12 Config Getting started: git config --global user.name "Your Name Comes Here" git config --global user. name and mail in every commit-message get all set config variables git config --list set config, for example git config --global core.editor emacs

13 Create and clone create a project (local): git init git add. git commit -m "initial commit" clone a remote repo: git clone URL

14 States and workflow Operations between sections: source: git book (staging area can be completely ignored (git commit -a))

15 States and workflow File lifecycle: source: git book

16 States and workflow Example: basic usage git init vim readme git status git add readme git commit -m initial commit vim readme git diff git status git add readme git diff --cached git status git commit -m bla git log -p -2 vim readme git reset HEAD readme

17 Remote repos Remotes: a local repo can have more than one remote repo as origin git clone adds remote called origin list remotes: git remote -v add remote: git remote add origin-test ORIGIN-URL get all data from remote: git fetch origin-test push BRANCH to remote: git push origin-home BRANCH show info about remote: git remote show origin (git push: pushes local branches to origin) useful for: collaborative work redundancy and backup!

18 Branching and merging Branching: very efficient use as often as possible!

19 Branching and merging internal date structure: a single commit source: git book

20 Branching and merging internal date structure: multiple commits source: git book git stores data as commit objects which point to snapshot

21 Branching and merging internal date structure: a branch source: git book a branch is just a pointer to a snapshot!!!

22 Branching and merging add branch testing: git branch testing source: git book

23 Branching and merging HEAD: source: git book HEAD marks the branch that is currently checked out

24 Branching and merging checkout branch testing: git checkout testing source: git book HEAD marks the branch that is currently checked out

25 Branching and merging changes in branch testing: source: git book

26 Branching and merging git checkout master: source: git book

27 Branching and merging changes in branch master: source: git book

28 Branching and merging basic branching: initial state source: git book

29 Branching and merging basic branching: create branch iss53 git branch iss53 source: git book

30 Branching and merging basic branching: do some work in branch iss53 git checkout iss53 edit and commit changes source: git book

31 Branching and merging basic branching: make a hotfix git checkout master git checkput -b hotfix (=git branch hotfix; git checkout hotfix) edit and commit changes source: git book

32 Branching and merging basic branching: after hotfix testing hotfix was bad: make more changes and commit or throw away changes: git branch -d hotfix hotfix was good: merge with master git checkout master git merge hotfix (=fast forward merge) git branch -d hotfix source: git book

33 Branching and merging basic branching: do work on iss53 git checkout iss53 edit and commit changes source: git book

34 Branching and merging basic branching: merge iss53 into master must have common ancestors source: git book

35 Branching and merging basic branching: merge iss53 into master git checkout master git merge iss53 possible merge conflict handling (git mergetool) git branch -d iss53 source: git book

36 Branching and merging collection of commands: create branch: git branch BRANCH change to branch: git checkout BRANCH create branch and change to is: git checkout -b BRANCH remove branch: git branch -d BRANCH merge branch BRANCH with HEAD: git merge BRANCH list branches: git branch -v list merged branches: git branch merged list unmerged branches: git branch no-merged

37 Branching and merging visualization: source: git book

38 Branching and merging commit often (checkpoint commits) think of history as development journal use feature branches (the commit history can be cleaned up afterwards...)

39 Branching and merging remote branches: until now all branches local! names of remote branches have the form: ORIGIN/BRANCH local master branch is tracking remote ORIGIN/master branch get infos about remote branches: git remote show ORIGIN

40 Branching and merging remote branches: actions get/update all remote branches: git fetch ORIGIN push local branch: git push ORIGIN BRANCH push local branch to other remote branch: git push ORIGIN BRANCH:REMOTEBRANCH

41 Branching and merging remote branches: actions get/update all remote branches: git fetch ORIGIN push local branch: git push ORIGIN BRANCH push local branch to other remote branch: git push ORIGIN BRANCH:REMOTEBRANCH merge changes in remote branch into HEAD: git merge ORIGIN/REMOTEBRANCH create local tracking branch of remote branch: git checkout -b BRANCH ORIGIN/REMOTEBRANCH delete remote branch: git push ORIGIN :REMOTEBRANCH show info about remote: git remote show ORIGIN

Workflows Integration-Manager Workflow: source: git book http://git-scm.com/ 1 The project maintainer pushes to their public repository. 2 A contributor clones that repository and makes changes.

42 Workflows Integration-Manager Workflow: source: git book 1 The project maintainer pushes to their public repository. 2 A contributor clones that repository and makes changes. 3 The contributor pushes to their own public copy. 4 The contributor asks maintainer to pull changes. 5 The maintainer adds the contributor s repo as a remote and merges locally. 6 The maintainer pushes merged/tested changes to the main repo.

43 Advanced topics advanced topics (sorted by importance): merge conflict handling staging tags rewriting history: rebasing, commit amending/squashing/reordering/splitting stashing (save unfinshed changes without commit for later use) blame, bisect (nice for debugging, error search) submodules (git repos as subdirectory of another git repo) aliases hooks

44 Administration with Gitolite adminstration of remote repository: Gitolite v3.3 at gitserver.pt.tu-clausthal.de included in backup system uses ssh user authentication via ssh-public/private key-pair access control

45 Administration with Gitolite howto: create account create new repository put existing directories and files under version control push existing local repository to new remote repo change access permissions delete repository

46 Administration with Gitolite create account: create new or use your existing ssh-pubkey (use nonempty password!) ssh-keygen -t rsa produces id_rsa (private key) and id_rsa.pub (public key) in $USER_HOME_DIR/.ssh be careful if you use multiple keys ( theowiki) send public key to Axel (NOT the private key!)

47 Administration with Gitolite create account: create new or use your existing ssh-pubkey (use nonempty password!) ssh-keygen -t rsa produces id_rsa (private key) and id_rsa.pub (public key) in $USER_HOME_DIR/.ssh be careful if you use multiple keys ( theowiki) send public key to Axel (NOT the private key!) check access with: ssh git@gitserver info hello robert, this is git@gitserver running gitolite3 v3.3-7 C CREATOR/[a-zA-Z0-9].* R W paw R W robert/rdmft R W robert/paw R W testing

48 Administration with Gitolite create new remote repository: git clone Cloning into test... Initialized empty Git repository in /home/git/repositories/robert/test.g warning: You appear to have cloned an empty repository. remote bare repository with url (initial access permissions are RW for the creator, none for others) local non-bare repository test with origin

49 Administration with Gitolite put existing directories and files under version control: create new remote repository copy files and directories to local repo add everything, commit, push

50 Administration with Gitolite push existing local repository to new remote repo: create new remote repository optional: remove old origin git remote rm origin add new remote in local repo: git remote add origin tell git to push all branches and tags: git config --add remote.origin.push +refs/heads/*:refs/ git config --add remote.origin.push +refs/tags/*:refs/t git push or push only selected branches with git push origin BRANCH

51 Administration with Gitolite change access permissions: for a wild repository (e.g. robert/test, optional): check current access permission (if empty only creator has RW): ssh git@gitserver perms -l robert/test

52 Administration with Gitolite change access permissions: for a wild repository (e.g. robert/test, optional): check current access permission (if empty only creator has RW): ssh git@gitserver perms -l robert/test add read permission for user: ssh git@gitserver perms robert/test + READERS user revoke read permission for user: ssh git@gitserver perms robert/test - READERS user add/revoke write permission for user: ssh git@gitserver perms robert/test +/- WRITERS user for other repositories: ask gitolite-admins to do it (Axel)

53 Administration with Gitolite delete remote repo: ask gitolite-admins to do it

54 Helpers graphical helpers: GNU/Linux: committing: git gui browsing, history,...: gitg - pretty, but slow with large repos gitk - very fast Mac: SourceTree GitX Android: agit

55 Weblinks Weblinks: git-svn course git book short git guide everyday-git git/docs/everyday.html cheat sheet http: //zrusin.blogspot.de/2007/09/git-cheat-sheet.html

56 Conclusion Next steps: generate ssh-keys and send them to Axel enjoy distributed version control...

57 Conclusion Next steps: generate ssh-keys and send them to Axel enjoy distributed version control... Branch and merge as often as possible! Questions?

58 Conclusion rebasing: git checkout experiment git rebase master

59 Conclusion All-day Workflow: 1 create private branch of public master branch 2 do work in private branch (implement feature, fix bug,...) 3 test commit often (checkpoint commits) feature branches 4 clean up private branch history with reset, rebase and commit amending 5 merge private into master when done commits in master should be atomic, linear, well documented (no checkpoint commits!)

GIT. CS 490MT/5555, Spring 2017, Yongjie Zheng

GIT. CS 490MT/5555, Spring 2017, Yongjie Zheng GIT CS 490MT/5555, Spring 2017, Yongjie Zheng GIT Overview GIT Basics Highlights: snapshot, the three states Working with the Private (Local) Repository Creating a repository and making changes to it Working