This document discusses Git tips and best practices, including: - Git is a distributed version control system designed for speed, integrity and distributed workflows. It stores snapshots of project files rather than file differences. - Merging incorporates changes from one branch into another but leaves an extra merge commit, while rebasing replays changes to a new base and cleans up history. - A successful Git branching model uses main branches like master and develop, and supporting branches like features, releases and hotfixes to integrate work.

1. Git Tips
by Arthur Shvetsov
CoreValue/MalkosUA

2. Agenda
● Git common principles and design goals
● Merging vs. Rebasing
● How to rewrite history?
● A successful Git branching model

3. What is Git?
● Git is a distributed revision control and source code
management (SCM) system with an emphasis on
speed, data integrity, and support for distributed, non-
linear workflows.
● Git was initially designed and developed by Linus
Torvalds for Linux kernel development in 2005, and has
since become the most widely adopted version control
system for software development.

4. Git design goals
● Speed
● Simple design
● Strong support for thousands of parallel branches
● Fully distributed
o full local repository
o offline commits
o full size repository
● Able to handle large projects like Linux kernel effectively
● Ensure integrity

5. Git drawbacks
● Big committed files will be in every clone of
repository
● No partial checkout
● No lock
● No support of empty directories

6. Git philosophy
● Commit early, commit often
● One commit represents one idea or one
change
o Make it easy to read patches
o Easy to revert unwanted changes later
● Your working directory, index and local
repository are your scratch pads

7. Git architecture

8. Nearly Every Operation Is Local

9. Snapshots, Not Differences
The major difference between Git and any
other VCS (Subversion and friends included) is
the way Git thinks about its data.

10. Tracking changes (most VCS)
Storing data as changes to a base version of each file

11. Tracking changes (the Git way)
Storing data as snapshots of the project over time

12. Git Generally Only Adds Data

13. File status lifecycle

14. The Staging Area
The staging area is a buffer between the
working directory and the project repository.

15. What happens when you create a
commit ?

17. What happens when you create a
new branch?
$ git branch testing

18. How does Git know what branch
you’re currently on?

19. What happens when you switch a
branch?
$ git checkout testing

20. Merging vs. Rebasing

21. Merging vs. Rebasing
git rebase and git merge - both of these
commands are designed to solve the same
problem - integrate changes from one branch
into another branch — they just do it in very
different ways.

22. A forked commit history
To incorporate the new commits into your feature branch,
you have two options: merging or rebasing.

23. Merging master into feature branch
$ git checkout feature
$ git merge master

24. Pros
● Simple to use and understand
● Merging is a non-destructive operation
● The existing branches are not changed in any way
Cons
● The feature branch will have an extraneous merge
commit every time you need to incorporate changes
● Visual charts of repository can have non-informative
branch lines
Git merge pros and cons

25. The Rebase Option
$ git checkout feature
$ git rebase master

26. Pros
● Much cleaned project history
● Eliminates the unnecessary merge commits required by git merge
● A perfectly linear project history
Cons
● Re-writing project history can be potentially catastrophic for your
collaboration workflow
● Rebasing loses the context provided by a merge commit - you can’t
see when upstream changes were incorporated into the feature
Git rebase pros and cons

27. Git rebase golden rule
Never use git rebase on public branches. Only rebase
local branches

28. When you rebase pushed branch, you’re
abandoning existing commits and creating
new ones that are similar but different

29. Interactive Rebase
$ git checkout feature
$ git rebase -i master

30. Pros
● Eliminating insignificant commits like this makes
your feature’s history much easier to understand.
This is something that git merge simply cannot do
Interactive rebase pros, no cons :)

31. Force Pushing
$ git push -f origin feature

32. Integrating an Approved Feature

33. Integrating an Approved Feature

34. Integrating an Approved Feature.
“Fast forward” effect

35. Rebasing a temporary branch
git checkout feature
git checkout -b temporary-branch
git rebase -i master
git checkout master
git merge temporary-branch

36. Git pull --rebase
By default, the git pull command performs a
merge, but you can force it to integrate the
remote branch with a rebase by passing it the --
rebase option.
$ git config branch.autosetuprebase always

37. How to rewrite history?

38. Git revert
Reverting undoes a commit by creating a new
commit. This is a safe way to undo changes, as
it has no chance of re-writing the commit
history.

39. $ git checkout hotfix
$ git revert HEAD~2

40. Git reset
Git reset as the dangerous method. When you
undo with git reset, there is no way to retrieve
the original copy—it is a permanent undo.

41. $ git checkout hotfix
$ git reset HEAD~2

42. Reverting vs. Resetting

43. git checkout
● checking out branches
● checking out commits - makes the entire
working directory match that commit
● checking out files - lets you see an old
version of that particular file, leaving the rest
of your working directory untouched

44. “Detached HEAD” state
$ git checkout HEAD~2

45. Multiple ways how to rewrite
history?
● $ git reset
● $ git rebase

46. Git cherry-pick
Applies the changes introduced by some
existing commits to specific branch
$ git checkout feature-branch
$ git cherry-pick <commit hash>

47. Stashing
Records the current state of the working
directory and the index, and cleans up the
working directory
$ git stash

48. Submodules
Submodule allows you to keep another Git
repository in a subdirectory of your repository
$ git submodule

49. A successful Git branching model

50. Decentralized but centralized

51. The main branches
● master
o contains production ready code
● develop
o an integration branch
o contains the latest changes
o used for nightly builds
o getting a production release
when merging with master

52. Supporting branches
● Feature branches
● Release branches
● Hotfix branches

53. Feature branches (topic branches)
● May branch off from:
o develop
● May merge back into:
o develop
● Branching name convention:
o anything except master, develop,
release-* or hotfix-*

54. Creating a feature branch
$ git checkout -b myfeature develop
Switched to a new branch “myfeature”
Incorporating a finished feature on develop
$ git checkout develop
Switched to branch 'develop'
$ git merge myfeature
Updating ea1b82a..05e9557 (Summary of changes)
$ git branch -d myfeature
Deleted branch myfeature (was 05e9557).
$ git push origin develop

55. Release branches
● May branch off from:
o develop
● Must merge back into:
o develop and master
● Branch naming convention:
o release-*
● Used for preparation of a new production release
● Allow minor bug-fixes

56. Creating a release branch
$ git checkout -b release-1.2 develop
Switched to a new branch "release-1.2"

57. Finishing a release branch
$ git checkout master
Switched to branch 'master'
$ git merge release-1.2
Merge made by recursive. (Summary of changes)
$ git tag -a 1.2
$ git checkout develop
Switched to branch 'develop'
$ git merge release-1.2
Merge made by recursive. (Summary of changes)
$ git branch -d release-1.2
Deleted branch release-1.2 (was ff452fe).

58. Hotfix branches
● May branch off from:
o master
● Must merge back into:
o develop and master
● Branch naming convention:
o hotfix-*

59. Creating a hotfix branch
$ git checkout -b hotfix-1.2.1 master
Switched to a new branch "hotfix-1.2.1"
$ git commit -m "Fixed severe production problem"
[hotfix-1.2.1 abbe5d6] Fixed severe production problem 5
files changed, 32 insertions(+), 17 deletions(-)

60. Finishing a hotfix branch
$ git checkout master
Switched to branch 'master'
$ git merge hotfix-1.2.1
Merge made by recursive. (Summary of changes)
$ git tag -a 1.2.1
$ git checkout develop
Switched to branch 'develop'
$ git merge hotfix-1.2.1
Merge made by recursive. (Summary of changes)
$ git branch -d hotfix-1.2.1
Deleted branch hotfix-1.2.1 (was abbe5d6).

61. Links and Literature
● Pro Git
● A successful Git branching model
● https://www.atlassian.com/git/tutorials/
● https://help.github.com/

62. Thank You!