1. NCARB CHECKOUT GIT

2. TOPICS IN THIS TALK
Introduction
Design Goals
Architecture
Using Git
- Basics
- Branching
- Collaboration
Git with Visual Studio
GitHub

3. GIT CULTURE
Everything is a Feature Branch
Commit often as work progresses
Developers don't ask for permission:
Clone and send a pull request
Maintainers pick and choose what to merge
Delegated network of trust

4. HISTORY
Developed in April 2005 by Linus Torvalds
PRE GIT
Linux Collaborators worked with patches
then Bitkeeper and fallout
NOW
Maintained by Junio Hamano

5. DESIGN GOALS
Distributed
Reliable
Quick
ACHIEVED THROUGH ARCHITECTURE AND GOOD CODE

6. DISTRIBUTED
The entire repository is copied.
Repository work is done offline
because you have the whole repository with you.

7. RELIABLE
Each object's filename is its hash:
easy to verify.
DISTRIBUTED == RELIABLE
If your repository is lost,
just ask for another developer's copy.

8. GIT FEATURE: QUICK
Snapshots, not diffs.
Fast operations on switching, merging, and committing.
Simple architecture with kernel hacker refinements.
DISTRIBUTED == QUICK
All operations are local.

9. ARCHITECTURE
EACH OBJECT'S FILENAME IS ITS HASH
OBJECTS
Files, Directories, Commits
POINTERS
Branches, HEAD, Tags

10. OBJECTS
Hello.txt
e965047ad7c57865823c7d992b1d046ea66edf78
Hellon
Directory Containing Hello.txt
2ea873e13e84497d7459150a0b2b662403e3bc2b
100644 blob e965047ad7c57865823c7d992b1d046ea66edf78 Hello.txt
Commit of Directory Containing Hello.txt
849d9a4ec0e853151ca4e8ff630feee25d701386
tree 2ea873e13e84497d7459150a0b2b662403e3bc2b
parent 2dce1bf1497951717f34a3a0d9605436e0477832
author DAnderson <danderson@ncarb.org> 1375967945 -0400
committer DAnderson <danderson@ncarb.org> 1375968283 -0400
Committed Hello.txt

11. POINTERS
Master Branch
.git/refs/heads/master
849d9a4ec0e853151ca4e8ff630feee25d701386
HEAD
.git/HEAD
ref: refs/heads/master
config
.git/config (snippet)
[remote "origin"]
url = https://github.com/davious/PrepGit.git
fetch = +refs/heads/*:refs/remotes/origin/*
[branch "master"]
remote = origin
merge = refs/heads/master

12. USING GIT
Basics
Branching
Collaboration

13. BASICS
Setup a Repository
Stage Files
Commit Staged Files
Undo Changes
Tagging

14. SETUP A REPOSITORY
CREATE A REPOSITORY
git init
Creates a repository filesystem in the .git subdirectory
SET NAME AND EMAIL
git config user.name "DAnderson"
git config user.email "danderson@ncarb.org"
Used in all commit files

15. Stages files; files are now tracked.
STAGE FILES
git add .
Further modifications to the
same file remain unstaged until the next add.
Shows which files are tracked, which files are modified
Shows line-by-line changes
between modified and staged/committed
Shows line-by-line changes between staged and committed
git status
git diff
git diff --cached

16. Amend is an easy way to add to what was just committed
COMMIT FILES
git commit -m "Commit message"
Branch now points to new commit file.
Commit files point to previous parent(s).
git commit -m "Commit message" --amend
or just redo the commit message
git log
Review past commits

17. UNDOING THINGS
git checkout -- filename1 filename2
git clean -f
Revert unstaged changed to their staged or committed state;
clean deleted untracked files
git reset HEAD
git reset HEAD filename1 filename2
Unstage staged files
git reset --hard
Throw away all work
git reset --hard HEAD^2
Undo last two commits

18. TAGGING
git tag -a 2.0 -m "Mid August Release"
Adds a tag on branch's last commit
git describe
2.0-12-8bd3fe1
Current commit description based on last created tag
{last tag name}-{revisions since}-{short hash of commit}

19. BRANCHES
Ethos
Creating
Merging
Resolving Conflicts
Rebasing
Squashing

20. BRANCH ETHOS
Branching, Checking out, and Merging
is cheap and fast
It keeps the master branch golden
We branch within our own repositories;
so, the main repository remains uncluttered
SO, FOR EACH ENDEAVOR, BRANCH

21. Switches your working files to this branches files
Shortcut: creates the branch and checks it out
BRANCH CREATION
git branch newbranch # master, newbranch >> A; HEAD >> master
Creates a new branch
git checkout newbranch # HEAD >> abranch
Note: Any staged files remained staged
git checkout -b newbranch # master, newbranch >> A; HEAD >> abranch
newbranch is now your current working branch

22. Lists branches; stars current branch
Deletes a branch
BRANCH MANAGEMENT
git branch
* master
feature1
git branch -D feature1

23. MERGING
git checkout master
git merge abranch
Merges changes in abranch into master
FAST-FORWARD MERGE
When commits have only been added to a branch,
just point to the branch's commit object
master >> A
master, newbranch >> A
master >> A <- B << newbranch
A <- B << master, newbranch

24. MERGING
COMPOSITE MERGE
When both branches have changed
and can be cleanly merged,
a new commit object is created;
it has two parents.
B (master work)
↙ ↖
A D (merge)
↖ ↙
C (newbranch work)

25. CONFLICTS
git merge abranch
Auto-merging hello.txt
CONFLICT (content): Merge conflict in hello.txt
Automatic merge failed; fix conflicts and then commit the result.
git mergetool
git commit
The result is just like a composite merge.
Typical Conflict Markup
<<<<<<< HEAD
Line modified in master
=======
Line modified in abranch
>>>>>>> abranch
git merge abranch
/conflict: you can hand edit it/
git add .
git commit

26. REBASING
Reconfigure branch history so that the same changes are
based on a different commit
Reconfigures abranch so that when master merges it,
it is a fast-forward merge
B
↙
A ⇒ A ← B ← C
↖
C
git checkout abranch
git rebase master

27. Brings up an edit-list of commits to squash together
SQUASHING
When you are already are without conflicts...
git rebase master -i --autofix
Undoes all commits, but keeps changes staged for a commit
Commit to master branch in one commit
git reset --soft master
git commit -m "abranches work, now in one commit"
git checkout master
git merge --squash abranch
git commit -m "abranch in one commit"

28. COLLABORATING
Cloning
Pull
Push

29. CLONE
git clone https://github.com/ncarb/Repo.git
Init + Copies repository + adds remote references
git remote add me https://github.com/davious/Repo.git
Adds a remote
git fetch
Brings down objects from remote repository
updates remote branch stored locally

30. Shortcut for doing a fetch and
Set a branch to track origin's
PULL
git pull
Shortcut for doing a fetch and
merging changes into the branch
git pull --rebase
rebasing the branch to be a fast-forward of the remote
git branch -u origin/master
master branch
Set a new branch to track origin's master branch
git checkout -b abranch origin/master

31. Pushes local commits to the remote.
Pushes a tag to a remote repository
PUSH
git push [remote]
If there have been changes since your last fetch,
your push will be cancelled.
git remote set-url --push origin https://github.com/davious/Repo.git
Changes the default repository you push to
git push -f
Force the remote to accept out-of-sync changes.
Not usually done while collaborating.
git push origin 2.0

32. VISUAL STUDIO INTEGRATION
msys-git
posh-git
GitHub for Windows
See Git
Visual Studio Git Provider
git-tfs

33. MSYS-GIT
Basic Command-line support
Git Bash Shell
Git GUI

34. POSH GIT
Powershell Enhanced Git Command-line Experience
C:UsersdandersonDev [master +3 ~4 -0 | +0 ~1 -0]>
Fancy, color-coded command prompt
Auto-completed git commands and arguments
branch upstream: in sync , ahead, behind, both
files: staged , unstaged
+ = added files
~ = modified files
- = deleted files

35. GITHUB FOR WINDOWS
Simple GitHub account management
App eye-candy
Fun to view history
Fun to view unified diffs
Easy to sync local repositories
with GitHub repositories
Msys-Git and Posh-Git
are bundled in with it

36. SEE GIT
Visual Application for Git

37. VISUAL STUDIO GIT PROVIDER
Team Explorer:
Changed Files, Commit, Push, Pull,
Conflict Resolution
Solution Explorer:
File Status, History
Improvements forthcoming
Integrated with Team Foundation Service
Note: Solution Provider is git add agnostic

38. GIT-TFS
Plugin for Git command-line
git tfs clone http://tfs:8080/tfs/DefaultCollection $/Project
git checkout -b story
git commit -am "Progress"
git tfs pull
git tfs shelve "Shelveset Name"
git tfs checkintool
Allows you to use git for development
when repository is TFS
Note: Commits to TFS as one commit,
even when you have committed multiple times:
no need to rebase

39. GITHUB
Popular
Thriving Community
Great Code Web Experience
Organization Support
Pull Requests
Sophisticated Code Review
Repository Wiki
Issue Tracking
Low Cost
Web Api
Team City integration

40. GITHUB INTEGRATION
DEVELOPER EXPERIENCE
track main repository
pull request when ready for review
request is verfied by Team City
request starts code review
easy to comment directly on code changes
in GitHub
GitHub provides email notifications
on build status and code review
ability to push branches to individual
account to collaborate with team members

41. GITHUB INTEGRATION
REVIEWER EXPERIENCE
Pull Requests are checked by Team City;
notifications in pull request comments
Easily see if request will merge without conflicts
Can use John Resig's Node.js module Pulley
to rebase pull requests and close it

42. CONCLUSION
Git is a well-designed version control system.
Microsoft supports Git.
We are using git locally with git-tfs right now.
—
GitHub offers a sophisticated repository service.
Team City supports Git and GitHub.
We could be using GitHub right about now.