Getting Git

Intros

• Name
• Job/Role
• Length of time at Rackspace
• What you hope to get from this class
• Previous experience with version control tools

What is Version Control

• A time machine for files and projects
• Snapshots/checkpoints of the project as a timeline
• Also referred to as revision control

Why use Version Control?

What should we use Version Control for?

• Different kinds of files
  • Text files
    • Scripts, config files, software, etc.
  • Binary files (with caveats)
  • Images / logos (with caveats)
• Files that are shared with others
  • Anything that can be changed by multiple folks
• Managing the flow of changes
  • Deploying known versions of files

What is Version Control

Graphic from http://www.git-tower.com/learn/git/ebook/command-line/basics/what-is-version-control

Nomenclature

• Version control
• Source control
• Revision control

Use Case 1:

• Multiple people (team members) working on the same stuff

Use Case 2:

• Keeping track of changes as you manage a system

Use Case 3:

• Tracking / managing common configs across multiple systems

Work Flow

• Get / open a repository
  • Pull down changes shared with you by others
• Create a branch for your work
• Do some work
  • Check in (commit) changes periodically
• Push your branch to a server to share your work with others
• Merge branches to bring changes into the main "master" branch
• Lather, rinse, repeat

Work Flow

• Each step in that workflow maps to a Git command
  • or a set of Git commands
• You can map your own workflow activities to Git
  • It is really flexible
• We will work on labs that illustrate all these workflow steps

What is Git?

What is Git

• From the web: Git is a free and open source distributed version control system designed to handle everything from small to very large projects with speed and efficiency.
• Git is a suite of tools for you to implement version control
  • The core stuff is command line
  • GUIs are available (more on that later)

Installing Git

• Git is available for all the major OSes
  • Linux, Windows, OS X
• http://git-scm.com/downloads
• We will experience this in the upcoming lab

What is a repository?

• A repository is the place that stores all the data for your version controlled directory
  • database for all the versions, metadata, file contents, etc.
• A repository can live on a local machine, cloud server, or other nebulous device
• Repositories can be cloned and shared

Git Commands - init

• Get / open / create a repository

git init .

Git Commands - add

• Do some work
  • Check in (commit) changes periodically
• To commit your changes first you have to stage them
  • Tell Git which changes you will be committing

git commit -m "my cool comment"

git add my_file.txt image.jpg

Git Commands - rm

• Remove a file (or files) from the repo

git rm my_file.txt image.jpg

Git Commands - status

• Find out the status of the repo

git status

Git Commands - reset

• Unstage a change
• (after an add)

git reset new_file.txt

Git Commands - undo an edit

• Undo all edits to a file 
• Great caution is advised here

git checkout -- changed_file.txt

Lab 1

https://github.com/jeremyprice/GettingGit/blob/master/lab01.md

Branching, Merging, and Conflicts

Workflow Continued

• Working linearly on a project doesn't scale well
• We need to be able to work on parallel sets of changes
• Thankfully, we have branching and merging

Branching and Merging Illustrated

Branching

• Creating a branch called nice_feature

• Make that branch the active branch

git branch nice_feature

git checkout nice_feature

Branching

• Shortcut: Creating a branch called nice_feature and make it active

git checkout -b nice_feature

Merging Branches

• Merging branches asks Git to take the changes from one branch and put them in the other
• Merge changes from nice_feature into master

git checkout master
git merge nice_feature

A note about the master branch

• The master branch is special
• It is considered the core branch that changes are merged into
• By convention, master is usually a known state of the files in the repository
• It is not the only branch you can merge changes into
• From Git's perspective it is just any old branch

Conflicts

• Merge conflicts happen when you try to merge changes that overlap from one branch to another 
• Example: in your README file

  • Branch A: Hello world!

  • Branch B:Goodbye world!

• Git can't tell which one it should go with, so it tells you to pick

Lab 2

https://github.com/jeremyprice/GettingGit/blob/master/lab02.md

GitHub for Collaboration

GitHub

• GitHub is a web-based Git repository hosting service
  • Centralized repository
• Social coding features
  • pull requests
  • documentation (markdown)
  • wikis
  • issue tracking
  • small websites
  • history browsing
  • code reviews
• Example: https://github.com/jeremyprice/GettingGit

Lab 3

https://github.com/jeremyprice/GettingGit/blob/master/lab03.md

Other Topics

GUI Clients

• (Mac) Tower - http://www.git-tower.com
• (Mac) GitHub - http://mac.github.com
• (Win) GitHub - http://windows.github.com
• (Mac, Win) SourceTree - https://www.sourcetreeapp.com/
• (Linux) gitg - https://wiki.gnome.org/Apps/Gitg/

Good list of GUI apps:

• http://git-scm.com/downloads/guis
• https://git.wiki.kernel.org/index.php/InterfacesFrontendsAndTools

Demo of Git GUI

SourceTree

Further reading

• Git Pro book - http://git-scm.com/
• Git Immersion tutorial - http://gitimmersion.com/
• Try Git - https://try.github.io/
• Learn Git branching - http://pcottle.github.io/learnGitBranching/
• Git Tower - http://www.git-tower.com/learn/git/ebook/
• Getting started with GitHub - https://www.youtube.com/watch?v=TAObtTxBUzk
• Good advice about Git Style - https://github.com/agis-/git-style-guide

Desk Reference

Cheat Sheet

http://byte.kde.org/~zrusin/git/git-cheat-sheet-large.png