Git

What is Git?
Distributed version control system (DVCS)
SVN = Centralized version control system
Mercurial, Bazaar are other DVCS
Initially designed and developed by Linus
Torvalds to manage Linux kernel code base
when BitKeeper revoked free license.

SVN (Centralized VCS) overview

Git (Distributed VCS) overview

Git (Distributed VCS) overview
(cont)

Why Git?
Embraced by all major hosting sites:
Github, Google Code, CodePlex, BitBucket
Used by major projects
Linux kernel, Android, ASP.NET MVC,
Facebook, Eclipse, Twitter Boostrap, ...

• Able to work disconnected (ex. VPN / home)
o (Almost) everything is local, fast
o Log is always available
o Private workspace
 Able to commit whenever, create snapshots,
push when ready (off VPN, done hacking)
 Share when ready, ability to modify previous
commits before sharing
• Local branching, easily switch gears when
customer calls (isolate work units)
 features, bug fixes, proof of concepts, etc
Why Git? - Benefits

Terms
HEAD
last commit of current branch
HEAD^
parent of HEAD
master
default development branch (trunk)
origin
default upstream repository (name of remote
when git clone was used)

Terms (cont.)
HEAD^ == HEAD~1 # parent of HEAD
HEAD^^^ == HEAD~3
master^^^ == master ~3

git init
New
git clone <url>
Existing
run at the project's top-most directory
creates a .git directory
Initializing

Review previous commit
git show --stat
git show --name-status
info about last commit
git show HEAD
git show HEAD^^^
git show master~10
git show @{yesterday}
git show master@{May.16}

Log
git log
git log --name-status
git log --oneline --graph --all
git log --author="Sean Lynch"
git log --grep="commit.*message.*text"
git log -- some/file
limit by changes to specific file
git timeline / git lol
custom aliases

Branching
git branch <branchname>
git checkout <branchname>
git checkout -b <branchname>
Create new branch and switch to
git branch [-a -l -r]
List branches (all, local, remote)
git merge <branchname>
Merge branch into current branch (ex. master)

Stashing
git stash
git stash [save message]
git stash list
git status apply
git stash clear
git stash branch <branchname>

Making a release (tagging)
git tag -a <name>
Create an annotated tag (with message)
git push --tags
Push tags to remote
git tag
list all tags

Remotes
git remote -v
git remote add <name> <url>
git remote show <name>
git branch --set-upstream master origin/master
Set local branch to track remote branch
git svn
http://git-scm.com/book/en/Git-and-Other-Systems-Git-
and-Subversion

Updating (Push/Pull)
git fetch / git merge
Fetch latest changes from origin, need to
use git merge to apply.
git pull
Pull latest changes from origin (fetch +
merge)
git push [remote_name] [branch_name]

Reverting
git checkout .
Revert changes to all files into working directory,
overwriting any local changes. This is most similar to
"svn revert"
git checkout -- <filename>
Revert changes to a file in working directory
git log --diff-filter=D -- <filename>
git checkout <deleting_commit>^ -- <filename>
Restore a deleted file

Reverting (cont.)
git reset HEAD
Unstage something
git reset HEAD^
forget about a commit, load it back into the staging area
git reset --hard HEAD / git checkout -f
Return to last committed state (discard all local
changes). Can not be undone (without reflog)

Reverting (cont. more)
git commit --amend
Change last commit (correct the previous commit, with
the staged changes)
git revert HEAD
Revert changes (creates a new commit)

Getting Started
Install
Configuration
Ignores

Install
Windows
Git for Windows: http://msysgit.github.com/
Git Extensions:
http://code.google.com/p/gitextensions/
TortoiseGit: http://code.google.com/p/tortoisegit/
Mac
Homebrew: brew install git bash-completion
SourceTree: http://www.sourcetreeapp.com/
GitHub for Mac: http://mac.github.com/

Configuration
git config --global user.name "Sean Lynch"
git config --global user.email "sean.lynch@sbcs.com"
git config --global core.autocrlf true #Windows
git config --global core.autocrlf input #Macs
git config --global color.ui true
git config --global log.decorate true
git config --list
cat ~/.gitconfig

Configuration (aliases)
git config --global alias.st status -s
git config --global alias.co checkout
git config --global alias.br branch
git config --global alias.ci commit
git config --global alias.timeline=log --graph --
pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s
%Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit --
date=relative --all

Ignores
git config --global core.excludesfile
~/.gitignore_global
Collection of .gitignore templates by language /
framework
https://github.com/github/gitignore

Review
git init
git clone
git add
git status
git commit
git log
git branch
git checkout
git merge
git push
git fetch
git pull

Extras - Modifying history
git commit --amend
Modify previous commit. Useful to update
message or include missing file without
creating a new commit
git rebase -i
Rewrite history. Squash, reorder, by
dropping

Extras
git submodule
git subtree

Finding regressions
git bisect start
git bisect good <commit>
git bisect bad <commit>
git bisect visualize
git bisect reset

Best practices
Don't develop off master, use
develop/feature/issue/etc branches

Help / Documentation / Reference
git <command> --help
http://gitref.org/
http://git-scm.com/book
http://help.github.com/
http://www.codingdomain.com/git/tricks/
http://jonas.nitro.dk/git/quick-reference.html
http://gitimmersion.com/
http://marklodato.github.com/visual-git-guide/

Git

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