G I T F O R S Y S T E M A D M I N S

J U S T I N E L L I O T T P E N N S TA T E U N I V E R S I T Y

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W H AT I S V E R S I O N C O N T R O L ?

• Management of changes to documents like source code, scripts, text files

• Provides the ability to check documents in and out of a versioning system

• Version Control System (VCS)

• Source Code Management (SCM)

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W H Y S H O U L D Y O U U S E I T ?

• Enables you to easily back out of mistakes

• Removes the risk of updating your scripts and code

• Excellent for collaboration with others

• Greatly enhances your ability to be agile and move quickly with scripts and coding.

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G I T V E R S U S S U B V E R S I O N

• Lightning fast! Checkouts are MUCH faster

• Clients have the full repo

• Distributed versus centralized

• No need for constant network access

• Easier to ignore files and edit other properties

• Git easily handles renaming and moving files

• Branching and Merging is much easier in Git

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G I T: A G R E AT S C M T O O L

• Extremely fast performance

• Excellent data integrity

• Git checksums everything (SHA-1)

• Easy to learn and start small

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G I T O V E R V I E W

• Git is distributed

• All clients have the full repo

• Changes are applied to local repo first

• Backups are everywhere

• Each member of your team has a local copy

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G I T T E R M I N O L O G Y

• Repository

• Working Directory

• Staging Area

• Remote

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G I T F I L E C L A S S I F I C AT I O N S

• Tracked

• Already in the repo, Git is watching it

• Ignored

• Can exist locally, not in repo and git ignores it

• Untracked

• What's not tracked or ignored

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G I T F I L E S TAT E S

• Modified

• Is tracked, changed but not yet committed

• Staged

• Modified filed marked to go into next commit

• Committed

• Safely stored in the repo

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B A S I C G I T W O R K F L O W

Working Directory

Staging Area

Repository

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H O W T O I N S TA L L G I T

• Download from http://git-scm.com/downloads

• OS X: Terminal.app

• Windows: Git Bash

• Embedded with many Git GUI client apps

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C O N F I G U R I N G G I T

• $ git config

• Contains items such as name, email, editor, diff tool

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C O N F I G U R E L I N E E N D I N G S

• End of line characters differ based on client OS

• OS X and Linux use one invisible character

• LF (Line Feed)

• Windows uses two invisible characters

• CR (Carriage Return) + LF (Line Feed)

• Embrace the native line endings for each OS

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L I N E E N D I N G M O D E S

• core.autocrlf true

• Use for cross platform projects on Windows clients

• core.autocrlf input

• Use for cross platform projects on OS X clients

• core.autocrlf false

• Use only on single platform projects

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L I N E E N D I N G S O N O S X

Enable auto convert CRLF to LF:

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L I N E E N D I N G S O N W I N D O W S

Enable auto convert to LF on Windows by using git config to set core.autocrlf to true:

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C R E AT E A R E P O S I T O R Y

• $ git init ProjectName.git

• Initializes a new and clean repository in new directory

• $ git clone <repoURL> <directory>

• The process of copying an existing Git repository locally to your computer

• Copies the entire repository history and file revisions

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S TAT U S O F F I L E C H A N G E S

• How do I know what has changed?

• $ git status

• Status reports different states

• Untracked

• Modified

• Staged

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I G N O R I N G F I L E S

• Some files should never reside in the repo

• The .gitignore file solves this

• Specify file names, directory paths to ignore

• Supports Wildcards

*NotForRepo*, *.dmg

10.9.4-Lab-Image.dmg

LargeDataFile-NotForRepo.db

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A D D I N G F I L E S T H E R E P O

• Adding files are “staged”

• Why not just directly commit the changes?

• git add -v <file/folder_name>

• git add -v .

• git add -A

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U N S TA G I N G F I L E S

• File not yet tracked but staged:

• $ git rm --cached NewFile.txt

• Files already tracked in repo, revert to previous

• $ git reset HEAD FileName.txt

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C O M M I T T I N G C H A N G E S

• This process saves the revisions made to the repository

• Commit often - You will thank yourself later!

• Or else … Larger changes are much harder to pick apart and revert back to!

• Each commit should encapsulate a single fix*

• $ git commit -m <commit_message>

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V I E W I N G D I F F S

• Commits are all about what is different

• Viewing the differences

• $ git diff <FileName>

• GUI Apps

• Kaleidoscope, FileMerge, Changes.app, etc.

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V I E W I N G C O M M I T L O G S

• $ git log

• $ git log -p -2

• Lists changes in last two commit entries

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B R A N C H E S

• “master” is the default branch

• Merging of branches is where Git excels

• Help to separate lines of development

• “Git Flow” is a popular branching model

• Ex: Master, Hotfix, Development, Feature, Release

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B R A N C H E S

• $ git checkout master

• Create and switch to new branch

• $ git checkout -b <branch>

• Delete branch

• $ git branch -d <branch>

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H E A D R E F E R E N C E

• HEAD is a reference to latest commit in branch OR a specific commit

• What does "detached HEAD" mean, and why should I care?

• Occurs when you check out a specific commit in a branch versus the latest commit of branch

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C O M M A N D L I N E D E M O

• Create Repo

• Create .gitignore

• Add Files

• Commit Changes

• Review Logs

• View Diffs

• Checkout commit

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R E M O T E R E P O S

• Local repo on your client only

• Remote is a Git host to push to

• You clone from remotes

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R E M O T E R E P O S

• Network Based

• SSH

• HTTPS

• Git Protocol (daemon)

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S E L F - H O S T E D R E P O S

• SSH

• Enable SSH, create “bare” repository on server

• Atlassian Stash

• Enterprise GitHub

• GitLab

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R E M O T E R E P O S

• 3rd Party

• GitHub, BitBucket, Google Code

• CodeSpaces, SourceRepo

• Assembla, Gitorious

• git.psu.edu (For Penn Staters)

• And possibly more, I’m sure…

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C L O N I N G A R E P O S I T O R Y

• The process of copying an existing Git repository to your computer

• A cloned repo includes the entire file history changes and commit messages

• Git clone command example:

• $ git clone https://server.edu/RepoName.git

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P U S H I N G C H A N G E S

• $ git push origin master

• Push (upload) the ‘master’ branch to the ‘origin’ remote host

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G U I C L I E N T S

• http://git-scm.com/downloads/guis

• GitHub (OS X and Windows)

• SourceTree (OS X and Windows)

• Tower (OS X)

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B A S I C S O F G I T H U B D E M O

• Create Repo

• Create .gitignore

• Add Files

• Commit

• View Diffs

• Review Logs

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S O U R C E T R E E

• Integrated support for Git hosting services

• GitHub, BitBucket, Kiln, Stash

• Helps to simplify more complex tasks

• Decent UI

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S O U R C E T R E E D E M O

• Create repo

• Create .gitignore

• Add files

• Commit changes

• Review Logs

• View Diffs

• Create Branch

• Merge Branch

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L E S S O N S L E A R N E D

• Start small

• Pick just one project to manage with Git

• Use remotes when ready

• GitHub, BitBucket, SSH host

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L E S S O N S L E A R N E D

• Take the time to write good commit messages

• There will be a time when you need to search your commit messages and it will really help you out

• Be nice to your future self

• “Where / when / how did I fix that issue?”

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G I T C O M M A N D L I N E H E L P

• $ git help

• $ git help <command>

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R E S O U R C E S A N D T R A I N I N G

• Official Git Site

• http://git-scm.com

• Git Cheat Sheets

• Git Pro Book

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R E S O U R C E S A N D T R A I N I N G

• http://try.github.com

• http://atlassian.com/git

• O’Reilly

• “McCullough and Berglund on Mastering Git”

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Q & AJustin Elliott

jelliott [at] psu.edu !

@justindelliott

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T H A N K Y O U .

Justin Elliott jelliott [at] psu.edu

!@justindelliott

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