Git Basics: Climbing the Totem Pole

© Matthew Salerno, 2012

Git Basics: Climbing the Totem Pole

by Matthew SalernoGithub: https://github.com/seldomatt

Twitter:@seldomattLinkedin: http://www.linkedin.com/pub/matthew-salerno/9/62b/584


Git vs. Github


Git vs. Github

GIT• Revision control and source

code management system


Git vs. Github


code management system • Created by Linus Torvalds

(Linux) in 2005


Git vs. Github



(Linux) in 2005

GITHUB• Hosting service for software

projects that use Git


Git vs. Github



(Linux) in 2005

GITHUB• Hosting service for software

projects that use Git• Started in 2008, now 1m+

users


Git vs. Github

• GitHub – has a graphical user interface


Git vs. Github

• GitHub


Git vs. Github

• Git – run through the command line


Git vs. Github

• Git – run through the command line– Tracks changes to a file or directory by storing

commits (versions) to a local repository


Git vs. Github


commits (versions) to a local repository– Local changes can be pushed to remote repository

(GitHub)


Git vs. Github


commits (versions) to a local repository– Local changes can be pushed to remote repository

(GitHub)– Fork/clone projects from remote repositories to

local repos, and much more…


Git vs. Github

• Git


Part of being a programmer isbreaking down complexity into more manageable parts


We’re going to try to swallow a manageable, bite-sized portion of Git.


What We Will Cover

• Init – creating a local repository


What We Will Cover

• Init – creating a local repository• Add – staging changes


What We Will Cover

• Init – creating a local repository• Add – staging changes • Commit – commit changes (saves a version)


What We Will Cover

• Init – creating a local repository• Add – staging changes • Commit – commit changes (saves a version)• Status/Log – see staged/unstaged changes,

commit history


What We Will Cover


commit history• Push – create a remote repo and push

changes from local repo (GitHub)


What We Will Cover


commit history• Push – create a remote repo and push

changes from local repo (GitHub)• Fork/Clone – work on someone else’s project


What We Won’t Cover

• Installing Git


What We Won’t Cover

• Installing Git • Branching, merging, and a host of other

operations that would be central to using git to manage professional projects


GIT: BUILDING THE TOTEM POLE


WORKING TREE


WORKING TREE

• Files and directories that the user alters in an editor or otherwise (example.rb, ‘rails_app’ directory)


WORKING TREE

• Files and directories that the user alters in an editor or otherwise (example.rb, ‘rails_app’ directory)

• ACTIONS:– WRITE CODE– DELETE CODE– SAVE (LOCALLY)


Local Repository


Local Repository

The local repository is where git stores versions, or commits, of your working tree


Let’s create a local git repository

• From the command line, navigate to our working tree directory


Let’s create a local git repository

• From the command line, navigate to our working tree directory

• Run ‘git init’ command/working tree $ git init .


Working Tree


Working Tree

Local Repository


Working Tree

Local Repository

What’s Missing?


Index/Staging Area


Index/Staging Area

Index is a collection of changes to the working tree waiting to be saved to the repository as a

commit


Index/Staging Area

Index is a collection of changes to the working tree waiting to be saved to the repository as a

commit

(the On-Deck circle of working tree changes)


Index/Staging Area

When we make changes to the working tree, we add them to the index(staging area) with the ‘git

add’ command


Git Add

• Make some changes to the working tree


Git Add

• Make some changes to the working tree• /working tree $ git add .


Git Add

Our index is now a snapshot of our working tree in it’s current state


Git Add

We can keep ‘git add’-ing changes to update the index


Git Add

• Added changes are ‘staged’. Changes to the working tree that have not been added to the index are ‘unstaged’


Git Add

• Added changes are ‘staged’. Changes to the working tree that have not been added to the index are ‘unstaged’

• $ git status will show us what changes have been staged and which have not


Eventually, we’ll come to a point where we want to save a version of our working tree

in it’s current state.


COMMIT


COMMIT

• A commit is a saved version (snapshot) of the working tree


COMMIT


• when git commit is executed, all ‘staged changes’, i.e. the current index, are saved to the local repo.


COMMIT


• when git commit is executed, all ‘staged changes’, i.e. the current index, are saved to the local repo.

• the index is then cleared out, making room for future changes to be staged and saved to the local repo as future commits


COMMIT

• $ git status . to make sure all changes are staged


COMMIT

• $ git status . to make sure all changes are staged

• $ git commit –m ‘commit message’


COMMIT

If we leave off the –m tag, git will open VIM, PICO, or whatever editor it can find in our bash

settings to enter a commit message


COMMIT

If we leave off the –m tag, git will open VIM, PICO, or whatever editor it can find in our bash

settings to enter a commit message

Don’t forget the –m tag!


COMMIT

• git commit records the snapshot(index) of all staged content to the local repository


COMMIT


• Each commit is uniquely identified


COMMIT


• Each commit is uniquely identified • The commit can now be compared, shared, or

reverted to if necessary


RECAP


RECAP

Working Tree • Write, Delete, Save• Local Drive


RECAP


Index• Snapshot of the working tree • $ git add stages by updating the index


RECAP


Index• Snapshot of the working tree • $ git add stages by updating the index

Local Repository• Local repository stores commits

(versions) of the working tree• $ git commit saves all staged changes

(index) to local repo


Now we want to share with the world…


Remote Repo


Remote Repo

Step #1 – Create a remote repository


Remote Repo

Github will give you a URL for that repository, i.e.

[email protected]:username/reponame.git


Remote Repo

Step #2 – synchronize between local and remote repo


Remote Repo

• $ git remote add


Remote Repo

• $ git remote add– Allows us to set up an alias for our remote repo


Remote Repo

• $ git remote add– Allows us to set up an alias for our remote repo– $ git remote add [alias] [email protected]:

[username]/[reponame].git


PUSH!

Step #3 – push commits from local repo to remote repo


PUSH!

• $ git push [alias] [branch]


PUSH!

• $ git push [alias] [branch]– We’ll use master as our branch, but you could

push from any number of branches


PUSH!

• $ git push [alias] [branch]– We’ll use master as our branch, but you could

push from any number of branches– $ git push basic master


PUSH!

We’ve now successfully pushed our commit from the local repo to the remote repo.


PUSH!

We’ve now successfully pushed our commit from the local repo to the remote repo.


What if we want to work on someone else’s code?


FORK/CLONE


FORK


FORK

In forking someone’s else’s project repo, you are creating a new remote repository with identical

contents…


FORK

…but a forked repo only exists on github. To work on the project, we need to clone the repo

to our local machine…


CLONE


CLONE

$ git clone https://github.com/username/reponame.git


CLONE

Now we can interact with the cloned repo as we would any other (adding, commiting, pushing)


CLONE

We can also configure remote aliases pointing to the original forked repo to keep track of updates

to the original project, pull from the original repo, merge with our own files, etc.


CONCLUSION/RESOURCESTHE TOTEM POLE IS COMPLETE…


BASIC WORKFLOW


BASIC WORKFLOW

• Creating a local repo (init)


BASIC WORKFLOW

• Creating a local repo (init)• Snapshotting (add)


BASIC WORKFLOW

• Creating a local repo (init)• Snapshotting (add)• Commits (commit)


BASIC WORKFLOW

• Creating a local repo (init)• Snapshotting (add)• Commits (commit) • Remote repo (remote add, push)


BASIC WORKFLOW

• Creating a local repo (init)• Snapshotting (add)• Commits (commit) • Remote repo (remote add, push)• Interaction (fork, clone)


THERE’S MUCH, MUCH MORE

• Resources– GitHub• http://help.github.com

– GitReference• http://gitref.org

– Code School – Try Git• http://try.github.com


GOOD LUCK!

Technology

Git Basics: Climbing the Totem Pole