This document provides an overview of a Git training course titled "Git-4-Geeks". It introduces Git and its history, explaining how Linus Torvalds created Git as a replacement for BitKeeper. It then covers common Git commands like init, clone, add, commit, branch, merge, rebase, and resolve conflicts. It discusses distributed version control and branching workflows. It also addresses tagging, remote repositories, and resolving merge conflicts. The goal is to teach attendees the fundamentals of using Git through scenario-based problems and solutions.

1. Git-4-Geeks
1st WEEK
DATE
GEEKY ACADEMY 2013

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2013
WHO ARE WE?
SALAH PIYA
Sala (Dean) Chalermthai
Siam Chamnan Kit
SChalermthai@sprint3r.com
Piya (Tae) Lumyong
-
piya.tae@gmail.com

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WHO ARE YOU?

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G
GIT
In software development, Git / tɡɪ / is a distributed version control and
source code management (SCM) system with an emphasis on speed. Initially designed and
developed by Linus Torvalds for Linux kernel development, Git has since been adopted by
many other projects.

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Git History
o Linux submitting patches model is quite interesting & unique in that time
o Linus hates CVS so much, he never believe in it
o He was in doomed maintaining Linux Kernel using Tarball + patch
o BitMover offer BitKeeper free usage. BitKeeper saved his life, but just for a while
o BitKeeper has a very strict Software License. People start to get upset
o Politics happened. Linus needs a replacement for BitKeeper
o Key criteria are:
o Needs to be Distributed SCM, like BitKeeper
o Needs to be highly Performance. 3 seconds max to apply a patch
o Guaranteed what goes in comes out correctly.

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Git History
• Nothing matches the criteria. Linus decided to creates his own SCM, Git.
• After the 2.6.12-rc2 Linux kernel development release, he make an announce:
“I’m not going to touch linux until I have a
replacement of BitKeepers” -- Linus Torvalds

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Git History
• Kernel 2.6.12 release was managed by Git
• Junio Harmano, major contributor was responsible for Git 1.0 release on 21 Dec 2005
• He remains as the project’s maintainer
• Linus on Git, Google Tech Talk: http://www.youtube.com/watch?v=4XpnKHJAok8

8. Git4G33ks
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Problem#:How is the course structured?
• Scenario based: Problems & Solutions

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Problem#:What is distributed SCM?

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Centralized CSM
Centralized
Repository
Developer
Developer
Developer

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Distributed CSM
Shared Repository
Developer
Developer
Developer
Local Repository
Local Repository
Local Repository

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Problem#: Is Git Installed?
$ git --version
git version 1.8.3.1

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Problem#: How to create a local repo?
$ git init

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Problem#: How to clone a remote repo?
$ git clone git@github.com:<username>/git_training.git
$ ssh-keygen
goto https://github.com/schalermthai/git_training
fork IT!

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Problem#: How to see history?
$ git log --oneline --graph
Note:
git config --global alias.tree "log --graph --decorate --oneline --abbrev-commit"

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C3
HEAD
master
C1 C2

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Problem3: How to make a commit?
$ git status
$ echo ‘hello world’ >> file1.txt
$ git status
$ git add file1.txt
$ git status
$ git commit -m “my first commit”

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C4
HEAD
master
C2 C3C1

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NOTE:
svn add != git add

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INDEX (staging)
Working Directory
C4
HEAD
master
C2 C3C1
git add
git commit

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Git diff
$ echo ‘how are you?’ >> file1.txt
$ git status
$ git diff

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Git diff
$ git add file1.txt
$ git status
# Changes to be committed:# (use "git rm
--cached <file>..." to unstage)## new file:
file1.txt

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Git INDEX
$ git diff

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Git INDEX
$ git diff --cached

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HEAD
INDEX (staging)
Working Directory
git add
git commit
git diff
git diff --cached

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INDEX is a SNAPSHOT!
$ echo 'oops!forgot something' >> file1.txt
$ git status

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INDEX is a SNAPSHOT!
$ echo 'oops!forgot something' >> file1.txt
$ git status
$ git diff
$ git commit -am “added file1”

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C5
HEAD
master
C3 C4C2C1

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Recap
• git add
• git commit
• git status
• git diff
• git checkout
• git reset
• git log

31. GIT BRANCHING
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S
GIT BRANCHING
- GIT branching is super easy & lightweight
- Branching is just a ref (AKA. pointer)
- SVN Branching is very heavyweight.
- Heavy enough so you wouldn’t want to create a branch unless it’s
super necessary

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Problem#: How to create a new branch?
$ git branch feature1
$ git branch
$ git checkout feature1
$ git branch
$ git tree

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C5
HEAD
master
C3 C4

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C5
HEAD
master
C3 C4
feature1
git branch feature1

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C5
HEAD
master
C3 C4
feature1
git checkout feature1

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Problem#: How to create a new branch and
switch to it?
$ git checkout -b feature2
$ git branch

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Problem#: How to create a new branch
from a commit point?
$ git checkout -b feature3 HEAD~1
$ git tree --all

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Makes 2 commits to feature2 branch and tag
it!
$ git checkout feature2
$ echo ‘1’ >> feature2.txt
$ git add feature2.txt
$ git commit -m “completed task 2.1”
$ echo ‘2’ >> feature2.txt
$ git commit -am “completed task 2.2”
$ git tree

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C5
HEAD
master
C3 C4
C6 C7
feature2

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Problem#: How to merge a branch?
$ git checkout master
$ git merge feature2

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C5
HEAD
master
C3 C4
C6 C7
feature2

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C5
HEAD
master
C3 C4 C6 C7
feature2
FAST FORWARDED!

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Switch back to feature3 branch and create 1
new commit!

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C5
HEAD
master
C3 C4 C6 C7
feature2
C8
feature3

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Switch back to master and now try to merge
feature3 branch!

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C5C3 C4
master
C6 C7
feature2
C8
feature3
C9
HEAD
Cannot make a fast-forward. So a new
merge commit is created

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Problem#: How to reset a branch?
$ git checkout master
$ git reset --hard feature2
$ git tree

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C5C3 C4
master
C6 C7
feature2
C8
feature3
HEAD

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Problem#: How to delete a branch?
$ git checkout master
$ git branch -D feature2
$ git branch
$ git tree

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C5C3 C4
master
C6 C7
feature2
C8
feature3
HEAD

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C5C3 C4
master
C6 C7
C8
feature3
HEAD

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Problem#: How to rebase a branch?
$ git checkout feature3
$ git rebase master

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C5C3 C4
master
C6 C7
C8
feature3
HEAD
C8’
Challenge: switch back to master and fast-forward it to feature3

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C5C3 C4
master
C6 C7
feature3
HEAD
C8’

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C5C3 C4
master
C6 C7
feature3
HEAD
C8’

57. Conflict
resolving
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Neither, Rebase or Merge did not make
conflicts go away!!

59. Git Remote
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Problem#: How to see remote details?
$ git remote -v
$ git remote show <remote>

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Problem#: How to see tracking remote
branches?
$ git branch -r
$ git branch -a

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Problem#: How to push changes to a branch
$ git push origin master

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Find a couple to work with!

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1. A & B clone from same repo
2. A add feature1, commit and push; B add feature2, commit and push
3. A add feature3, commit and push;
3. A add feature3, commit and push;
3. A add feature3, commit and push;

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Problem#: How to pull from remote?
$ git pull origin master

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Git pull == git fetch;git merge origin/master

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git tree --all

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Git pull --rebase == git fetch;git rebase
origin/master

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Problem#: How to diff with remote branch?
$ git fetch;
$ git diff origin/master
$ git diff ...origin/master
$ git diff ..origin/master

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Problem#: You want to pull but you are not
ready to commit?
$ git reset --hard HEAD~1
$ echo ‘experiment an idea’ >> feature3.txt
$ cat feature3.txt
$ git status
$ git pull origin master
STASH to rescue

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Problem#: How to stash changes?
$ git stash
$ git status
$ git pull origin master
$ git stash pop
Warning!: GIT STASH can create conflicts!

72. Tagging &
Branching Tips
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Problem#: Git checkout vs Git reset?
$ git checkout <commit>
$ git reset <commit>

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Problem#: What to do when you forgot to
create a feature branch?
$ git checkout master
$ touch feature6.txt
$ git add feature6.txt
$ git commit -m “complete feature6”

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Problem#: What to do when you forgot to
create a feature branch?
$ git branch feature6
$ git tree --all
$ git reset --hard origin/master
$ git tree --all

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Problem#: How to create a tag?
$ git tag v1.0
$ git tag v1.1 <commit>
$ git push origin v1.0

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Problem#: How to push to different remote
branch name?
$ git checkout -b myFeature5
$ git push origin myFeature5:feature5

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Problem#: How to delete a local branch?
$ git branch -D feature2

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Problem#: How to delete a remote branch?
$ git push origin :feature2

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Problem#: How to remove deleted tracking
branch?
$ git branch -a
$ git fetch
$ git prune
$ git fetch -p

81. UNDO
CHANGES
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Problem#: How to revert a public commit?
$ git revert #commit

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Problem#: How to amend to local last
commit?
$ echo ‘finish feature4’ >> feature4.txt
$ git add feature4.txt
$ git commit -m “complete feature4”
$ echo ‘forgot this’ >> feature4.txt
$ git add feature3-1.txt
$ git commit --amend

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Problem#: How to do rebase interactive?
$ git rebase -i HEAD~4
#you can move, delete, edit, squash commits

85. Git for
debugging
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Problem#: How to see who commit which line
of code and when?
$ git blame <file>

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Problem#: How to see which revision that
introduce the bug?
$ git bisect start
$ git bisect bad
$ git bisect good v1.0

88. Git Submodule
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Problem#: How to create a git submodule?
$ git submodule add <remote> <directory>
$ git status
$ git commit -m “added submodule”

90. Git Tips
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Problem#: How to cherry-pick commits?
$ git cherry-pick <commit>

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Problem#: How to remove untracked files?
$ git clean -df

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Problem#: How to add new remote?
$ git remote add <alias> <remote>
$ git fetch <alias>

94. Git Workflow
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Problem#: Git flow?
http://nvie.com/posts/a-successful-git-branch
https://github.com/nvie/gitflow

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Problem#: Code review with
Github/BitBucket Pull Request

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Problem#: Code review with Gerrit

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Feature Branch vs Branch by Abstraction
• Feature Branch == Poor man’s modular architect
• Feature toggle + Branch by abstraction
• Feature branch suffers when two team members start working on two different feature branches for
too long. git rebase origin/develop every day wont help much

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Summary
• Git is a very cool & powerful tool
• Once you understand its basic fundamental, you’ll start fall in love with its infinite potential
• Keep calm and geek on!

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