Git101 presntation for iRail Summer of code

1. Git 101
@jenssegers

2. In a world without Git

3. Distributed version control
• Speed
• Simple
• Non-linear development
• Fully distributed
• Large projects

4. Snapshots, no ∆

5. Distributed
Hannes
Pieter
Jens
Miet

6. Distributed and managed
Hannes
Pieter
Jens
Miet

7. Github
Hannes
Pieter
Jens

8. What is Github?
• Repository hosting service
• Visualization of changes
• Issue tracker

9. Installing Git
• Windows
Git Bash with MinGW
git-scm.com
• OSX and Linux
Terminal

10. Git configuration
$ git config --global user.name “Your Name”
$ git config --global user.email “your@email.com”

11. A new github repository
git@github.com:user/Hello.git

12. Creating a local repository
$ mkdir Hello
$ cd Hello
$ git init
Initialized empty Git repository in Hello/.git/
$ git remote add origin git@github.com:user/Hello.git

13. Git Basics

14. git add
Track files for the next snapshot
$ git add README
$ git add subfolder/
Add all files (including deleted files)
$ git add -A

15. git rm
Opposite of add, untracks file
$ git rm README
Recursive
$ git rm -r subfolder/

16. git commit
Create a snapshot of all the added files
$ git commit -m “Adding readme”
[master] created d9e1758: “Adding readme”
1 files changed, 1 insertions(+), 0 deletions(-)
Always add an appropriate commit message!

17. git commit (2)
Automatically detect changed and deleted files
$ git commit -am “Adding readme”
Update a previous commit
$ git commit -am “GUI refactoring”
$ git add new_file
$ git commit --amend

18. git push
Push commit snapshots to a remote repository
$ git push [remote] [branch]
$ git push origin master
Writing objects: 100% (3/3), 225 bytes, done.
Total 3 (delta 0), reused 0 (delta 0)

19. git pull
Pull updates from a remote repository
$ git pull [remote] [branch]
$ git pull origin master
remote: Total 3 (delta 0), reused 0 (delta 0)
Updating d9e1758..c3e12cc

20. git clone
Work on an existing repository
$ git clone [origin]
$ git clone https://github.com/user/repository.git
Cloning into ...
Unpacking objects: 100%, done.

21. Conflicts

22. Conflicts
A file was modified since the last pull
$ git push origin master
! [rejected] master -> master (non-fast-forward)

23. Inspecting the conflict
Update your repository
$ git pull
View conflict info
$ git status
Unmerged paths:
both modified: README

24. Resolving the conflict
Open the conflicted file in your favorite editor
$ nano README
<<<<<<< HEAD
Yes, this is Dog? ] local repository
=======
Who is Dog?
>>>>>>> a0b0bf3
] remote repository

25. Push merged file
$ git add README
$ git commit -m “Merging”
$ git push origin master

26. Branching

27. Branches

28. Typical branches
• Master
The latest stable version of the project
• Staging
The branch where the a beta version is tested before it is merged
into the master branch
• Feature X
A branch where a specific feature is being developed

29. Creating a branch
From the base branch
$ git branch feature-x
Switching to the new branch
$ git checkout feature-x

30. Merging a branch
Switch to the base branch you want to merge in
$ git checkout master
Merge with the branch
$ git merge staging

31. Updating a branch
Update a feature branch with master branch bug fixes
$ git checkout feature-x
$ git merge master

32. Removing a branch
$ git branch -D feature-useless

33. Tips and tricks

34. .gitignore
A list of files that should be ignored
# OS generated files
.DS_Store
.Trashes
Thumbs.db
# Config
Config.php

35. When all hope is lost
Revert all changes to the last pulled version
$ git reset --hard HEAD

36. Credential cache
Add cache to credentials to prevent typing username and password
over and over again
$ git config --global credential.helper cache
Default cache is 15 minutes, to change cache use
$ git config credential.helper 'cache --timeout=3600'

37. SSH keys
WARNING! Only when you do not have an existing key pair
$ ssh-keygen -t rsa -C "your@email.com"
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/you/.ssh/
id_rsa): [Press enter]
Enter passphrase (empty for no passphrase): [Type a
passphrase]

38. SSH keys (2)
Add your public SSH key to your github account (account settings)
$ cat ~/.ssh/id_rsa.pub
Test your settings
$ ssh -T git@github.com
Hi username! You've successfully authenticated, but
GitHub does not provide shell access.

39. Good luck
thanks
Tim De Pauw, Pieter Colpaert, Hannes Van De Vreken