git and github - suny oswegocs.oswego.edu/~csa/repo/talks/git-talk.pdf · 1 versioncontrol 2 git 3...

Git and GitHub

Dan Wysocki

February 12, 2015

Dan Wysocki Git and GitHub February 12, 2015 1 / 48

1 Version Control

2 Git

3 GitHub

4 Walkthrough


Version Control


Background

when dealing with a document which changes over time, a system forrecording and organizing those changes is important

books are released in separate volumeswith the dawn of computing, more incremental versioning became bothfeasible and necessary


Background

when dealing with a document which changes over time, a system forrecording and organizing those changes is importantbooks are released in separate volumes

with the dawn of computing, more incremental versioning became bothfeasible and necessary


Background

when dealing with a document which changes over time, a system forrecording and organizing those changes is importantbooks are released in separate volumeswith the dawn of computing, more incremental versioning became bothfeasible and necessary


Version Control Systems (VCS)

CVS (1986)

SVN (2000)Mercurial (2005)Git (2005)



CVS (1986)SVN (2000)

Mercurial (2005)Git (2005)



CVS (1986)SVN (2000)Mercurial (2005)

Git (2005)



CVS (1986)SVN (2000)Mercurial (2005)Git (2005)


Git


Background

an open source version control system created by Linus Torvalds

I designed with lessons learned from Linux

distributed version control systemnon-linear development history

I multiple developers working in parallel


Background

an open source version control system created by Linus TorvaldsI designed with lessons learned from Linux




Background


distributed version control system

non-linear development history



Background





Repository

a data structure which stores files and a record of changes

Git repositories are designed like filesystemsa Git repository is stored on a remote server, and each developer makesa local clonechanges are committed to the local repository, and the local repositoryis then pushed to the remote


Repository

a data structure which stores files and a record of changesGit repositories are designed like filesystems

a Git repository is stored on a remote server, and each developer makesa local clonechanges are committed to the local repository, and the local repositoryis then pushed to the remote


Repository

a data structure which stores files and a record of changesGit repositories are designed like filesystemsa Git repository is stored on a remote server, and each developer makesa local clone

changes are committed to the local repository, and the local repositoryis then pushed to the remote


Repository

a data structure which stores files and a record of changesGit repositories are designed like filesystemsa Git repository is stored on a remote server, and each developer makesa local clonechanges are committed to the local repository, and the local repositoryis then pushed to the remote


Commits

an update to a repository

contains:

I a short user-made description (basically a title)I an optional long descriptionI a record of changes made to the repository

F additions (+)F deletions (-)

I a unique identifier

every commit is stored in the repository’s history, and may be revertedto at any time


Commits

an update to a repositorycontains:






Commits


I a short user-made description (basically a title)

I an optional long descriptionI a record of changes made to the repository





Commits


I a short user-made description (basically a title)I an optional long description

I a record of changes made to the repository





Commits







Commits



F additions (+)

F deletions (-)I a unique identifier



Commits







Branches

a Git repository may be separated into multiple branches

the primary branch is conventionally named mastereach branch may be worked on independently, without affecting eachother

I essential for managing group projectsI still useful for single person projects, as functionality-breaking changes

may be worked on in separate branches while master remains intact

branches can be merged together, combining their commit historiespull requests

I a request to pull changes from one branch to anotherI similar to a commit (description, record of changes, unique identifier)I must be accepted before changes are committed, allowing collaborators

to review or test the code first


Branches

a Git repository may be separated into multiple branchesthe primary branch is conventionally named master

each branch may be worked on independently, without affecting eachother







Branches

a Git repository may be separated into multiple branchesthe primary branch is conventionally named mastereach branch may be worked on independently, without affecting eachother







Branches


I essential for managing group projects

I still useful for single person projects, as functionality-breaking changesmay be worked on in separate branches while master remains intact





Branches








Branches




branches can be merged together, combining their commit histories

pull requests




Branches








Branches





I a request to pull changes from one branch to another

I similar to a commit (description, record of changes, unique identifier)I must be accepted before changes are committed, allowing collaborators



Branches





I a request to pull changes from one branch to anotherI similar to a commit (description, record of changes, unique identifier)

I must be accepted before changes are committed, allowing collaboratorsto review or test the code first


Branches








Forks

a user may fork any repository they have access to, creating anindependent copy

the fork can be used to:

I keep a personal backupI take the project in a new directionI make changes to the repository, which will later be merged back in

just like branches on the same repository, branches from forkedrepositories may be merged via pull requestopen source projects often use the fork/pull request model foraccepting 3rd party contributions


Forks

a user may fork any repository they have access to, creating anindependent copythe fork can be used to:




Forks


I keep a personal backup

I take the project in a new directionI make changes to the repository, which will later be merged back in



Forks


I keep a personal backupI take the project in a new direction

I make changes to the repository, which will later be merged back in



Forks





Forks



just like branches on the same repository, branches from forkedrepositories may be merged via pull request

open source projects often use the fork/pull request model foraccepting 3rd party contributions


Forks





GitHub


Background

a proprietary hosting service for Git repositories, with added perks

created in 2008 by Tom Preston-Werner, Chris Wanstrath, and PJHyettwritten in Rubyunlimited free hosting for public repositoriespaid hosting for private repositories


Background

a proprietary hosting service for Git repositories, with added perkscreated in 2008 by Tom Preston-Werner, Chris Wanstrath, and PJHyett

written in Rubyunlimited free hosting for public repositoriespaid hosting for private repositories


Background

a proprietary hosting service for Git repositories, with added perkscreated in 2008 by Tom Preston-Werner, Chris Wanstrath, and PJHyettwritten in Ruby

unlimited free hosting for public repositoriespaid hosting for private repositories


Background

a proprietary hosting service for Git repositories, with added perkscreated in 2008 by Tom Preston-Werner, Chris Wanstrath, and PJHyettwritten in Rubyunlimited free hosting for public repositories

paid hosting for private repositories


Background

a proprietary hosting service for Git repositories, with added perkscreated in 2008 by Tom Preston-Werner, Chris Wanstrath, and PJHyettwritten in Rubyunlimited free hosting for public repositoriespaid hosting for private repositories


Repositories

adds additional features to normal Git repositories

displays various statistics about each repositoryrenders files written in the markdown markup languageallows users to write comments on just about anything, from individuallines of code to pull requestsprovides a wiki for each repositoryprovides an issue tracker for reporting bugs, proposing changes, andsetting milestones with optional deadlines


Repositories

adds additional features to normal Git repositoriesdisplays various statistics about each repository

renders files written in the markdown markup languageallows users to write comments on just about anything, from individuallines of code to pull requestsprovides a wiki for each repositoryprovides an issue tracker for reporting bugs, proposing changes, andsetting milestones with optional deadlines


Repositories

adds additional features to normal Git repositoriesdisplays various statistics about each repositoryrenders files written in the markdown markup language

allows users to write comments on just about anything, from individuallines of code to pull requestsprovides a wiki for each repositoryprovides an issue tracker for reporting bugs, proposing changes, andsetting milestones with optional deadlines


Repositories

adds additional features to normal Git repositoriesdisplays various statistics about each repositoryrenders files written in the markdown markup languageallows users to write comments on just about anything, from individuallines of code to pull requests

provides a wiki for each repositoryprovides an issue tracker for reporting bugs, proposing changes, andsetting milestones with optional deadlines


Repositories

adds additional features to normal Git repositoriesdisplays various statistics about each repositoryrenders files written in the markdown markup languageallows users to write comments on just about anything, from individuallines of code to pull requestsprovides a wiki for each repository

provides an issue tracker for reporting bugs, proposing changes, andsetting milestones with optional deadlines


Repositories

adds additional features to normal Git repositoriesdisplays various statistics about each repositoryrenders files written in the markdown markup languageallows users to write comments on just about anything, from individuallines of code to pull requestsprovides a wiki for each repositoryprovides an issue tracker for reporting bugs, proposing changes, andsetting milestones with optional deadlines


Organizations

in addition to individual users, organizations may be created

organizations may host free public repositories, and paid private onesmembers may have varying read/write permissionsteams of members may be created, which have permissions for specificrepositoriesevery organization has one or more owners, with the authority tochange the permissions of every other member


Organizations

in addition to individual users, organizations may be createdorganizations may host free public repositories, and paid private ones

members may have varying read/write permissionsteams of members may be created, which have permissions for specificrepositoriesevery organization has one or more owners, with the authority tochange the permissions of every other member


Organizations

in addition to individual users, organizations may be createdorganizations may host free public repositories, and paid private onesmembers may have varying read/write permissions

teams of members may be created, which have permissions for specificrepositoriesevery organization has one or more owners, with the authority tochange the permissions of every other member


Organizations

in addition to individual users, organizations may be createdorganizations may host free public repositories, and paid private onesmembers may have varying read/write permissionsteams of members may be created, which have permissions for specificrepositories

every organization has one or more owners, with the authority tochange the permissions of every other member


Organizations

in addition to individual users, organizations may be createdorganizations may host free public repositories, and paid private onesmembers may have varying read/write permissionsteams of members may be created, which have permissions for specificrepositoriesevery organization has one or more owners, with the authority tochange the permissions of every other member


GitHub Pages

free static website hosting service

each user, organization, and repository is permitted one websitefor users and organizations, that website is hosted at<user-name>.github.iorepositories are hosted at<user-name>.github.io/<repository-name>


GitHub Pages

free static website hosting serviceeach user, organization, and repository is permitted one website

for users and organizations, that website is hosted at<user-name>.github.iorepositories are hosted at<user-name>.github.io/<repository-name>


GitHub Pages

free static website hosting serviceeach user, organization, and repository is permitted one websitefor users and organizations, that website is hosted at<user-name>.github.io

repositories are hosted at<user-name>.github.io/<repository-name>


GitHub Pages

free static website hosting serviceeach user, organization, and repository is permitted one websitefor users and organizations, that website is hosted at<user-name>.github.iorepositories are hosted at<user-name>.github.io/<repository-name>


Walkthrough


Initialize Repo


Clone Repo

$ git clone <paste url here>Cloning into 'git-demonstration'...remote: Counting objects: 3, done.remote: Compressing objects: 100% (2/2), done.remote: Total 3 (delta 0), reused 0 (delta 0)Unpacking objects: 100% (3/3), done.Checking connectivity... done.


Add a File

in your editor of choice (which should be Emacs), create a file namedtest in the directory containing your repository, and write somethingin it


Commit Your Changes

$ git add test$ git commit -m "I created a test file and wrote things in it"[master 20ab3bb] I created a test file and wrote things in it1 file changed, 1 insertion(+)create mode 100644 test


Status Report

$ git statusOn branch masterYour branch is ahead of 'origin/master' by 1 commit.

(use "git push" to publish your local commits)nothing to commit, working directory clean

so far, we have commited a change to our local repository

we have yet to change the remote repository (hosted on GitHub)


Status Report

$ git statusOn branch masterYour branch is ahead of 'origin/master' by 1 commit.

(use "git push" to publish your local commits)nothing to commit, working directory clean

so far, we have commited a change to our local repositorywe have yet to change the remote repository (hosted on GitHub)


Pushing Local to Remote

$ git push origin masterUsername for 'https://github.com': dwysockiPassword for 'https://[email protected]':Counting objects: 3, done.Delta compression using up to 2 threads.Compressing objects: 100% (2/2), done.Writing objects: 100% (3/3), 316 bytes | 0 bytes/s, done.Total 3 (delta 0), reused 0 (delta 0)To https://github.com/dwysocki/git-demonstration.git

cb687c8..20ab3bb master -> master


Status Report

$ git statusOn branch masterYour branch is up-to-date with 'origin/master'.nothing to commit, working directory clean

now the remote and local repositories are in sync


Commit History


Viewing Previous Commits

copy the initial commit’s ID

$ git checkout <paste ID here>HEAD is now at cb687c8... Initial commit

now you should notice that test is gonewe have reverted to a previous commit





now you should notice that test is gone

we have reverted to a previous commit





now you should notice that test is gonewe have reverted to a previous commit


Returning to Latest Commit

$ git checkout masterPrevious HEAD position was cb687c8... Initial commitSwitched to branch 'master'Your branch is up-to-date with 'origin/master'.


Pulling Remote Changes

say another person on your team edited a file

to sync the updated remote with your local repository, simply pull



say another person on your team edited a fileto sync the updated remote with your local repository, simply pull



$ git pull origin masterremote: Counting objects: 3, done.remote: Compressing objects: 100% (2/2), done.remote: Total 3 (delta 0), reused 0 (delta 0)Unpacking objects: 100% (3/3), done.From https://github.com/dwysocki/git-demonstration* branch master -> FETCH_HEAD

20ab3bb..dcbd46c master -> origin/masterUpdating 20ab3bb..dcbd46cFast-forwardother_persons_file | 1 +1 file changed, 1 insertion(+)create mode 100644 other_persons_file


Handling Conflicts

say another person on your team edited a file, which you have alsoedited

both of you made these changes at the same timethe person who pushes first is none the wiserthe person who pushes second must deal with a merge conflict


Handling Conflicts

say another person on your team edited a file, which you have alsoeditedboth of you made these changes at the same time

the person who pushes first is none the wiserthe person who pushes second must deal with a merge conflict


Handling Conflicts

say another person on your team edited a file, which you have alsoeditedboth of you made these changes at the same timethe person who pushes first is none the wiser

the person who pushes second must deal with a merge conflict


Handling Conflicts

say another person on your team edited a file, which you have alsoeditedboth of you made these changes at the same timethe person who pushes first is none the wiserthe person who pushes second must deal with a merge conflict


Handling Conflicts

$ git add test$ git commit -m "Here goes"[master a20e398] Here goes1 file changed, 3 insertions(+), 1 deletion(-)

$ git push origin masterTo https://github.com/dwysocki/git-demonstration.git! [rejected] master -> master (fetch first)

error: failed to push some refs to 'https://github.com/dwysocki/git-demonstration.git'hint: Updates were rejected because the remote contains work that you dohint: not have locally. This is usually caused by another repository pushinghint: to the same ref. You may want to first integrate the remote changeshint: (e.g., 'git pull ...') before pushing again.hint: See the 'Note about fast-forwards' in 'git push --help' for details.


Handling Conflicts

$ git pull origin masterremote: Counting objects: 3, done.remote: Compressing objects: 100% (2/2), done.remote: Total 3 (delta 1), reused 0 (delta 0)Unpacking objects: 100% (3/3), done.From https://github.com/dwysocki/git-demonstration* branch master -> FETCH_HEAD

dcbd46c..db8b662 master -> origin/masterAuto-merging testCONFLICT (content): Merge conflict in testAutomatic merge failed; fix conflicts and then commit the result.


Handling Conflicts


Handling Conflicts

$ git add test$ git commit -m "That'll show em"[master 9af49d0] That'll show em$ git push origin masterCounting objects: 6, done.Delta compression using up to 2 threads.Compressing objects: 100% (6/6), done.Writing objects: 100% (6/6), 567 bytes | 0 bytes/s, done.Total 6 (delta 3), reused 0 (delta 0)To https://github.com/dwysocki/git-demonstration.git

db8b662..9af49d0 master -> master


Branches

to avoid this headache, we can work in separate branches

$ git checkout -b my-branchSwitched to a new branch 'my-branch'$ git push origin my-branchTotal 0 (delta 0), reused 0 (delta 0)To https://github.com/dwysocki/git-demonstration.git* [new branch] my-branch -> my-branch


Branches

now make some changes to your new branch, and push

$ git add test$ git commit -m "Making changes on my-branch"[my-branch d22de3d] Making changes on my-branch1 file changed, 2 insertions(+)

$ git push origin my-branchCounting objects: 3, done.Delta compression using up to 2 threads.Compressing objects: 100% (3/3), done.Writing objects: 100% (3/3), 347 bytes | 0 bytes/s, done.Total 3 (delta 1), reused 0 (delta 0)To https://github.com/dwysocki/git-demonstration.git

9af49d0..d22de3d my-branch -> my-branch


Merging

we can now directly merge my-branch with master (don’t do thiswith branches shared by multiple people, we’ll see why)

$ git checkout master$ git merge my-branchUpdating 9af49d0..d22de3dFast-forwardtest | 2 ++1 file changed, 2 insertions(+)

$ git push origin master


Pull Requests

when we want to merge our changes with the project’s master branch,it is a good idea to consult with the rest of your group

I keeps the group informedI gives them a chance to review your changes and suggest revisions

also allows people outside your group to submit changes, while leavingthe group with the final decision to accept or reject those changes


Pull Requests


I keeps the group informed

I gives them a chance to review your changes and suggest revisions



Pull Requests


I keeps the group informedI gives them a chance to review your changes and suggest revisions



Pull Requests

make a new branch, make some changes to it, and push them asbefore, but don’t merge with master

$ git checkout -b new-feature$ echo "Words words words words" > new-file$ git add new-file$ git commit -m "Adding new file"$ git push origin new-feature

now open your repository’s web page on GitHub


Pull Requests


Forks

create your own copy of another repository

has the benefits of working on separate branches, but with completeindependenceyou may create a pull request between your fork and the originalrepositorythis is how many open source projects accept contributionslarge projects in general benefit from using this model over branches,as it restricts who can directly edit the main project, allowing for codereview


Forks

create your own copy of another repositoryhas the benefits of working on separate branches, but with completeindependence

you may create a pull request between your fork and the originalrepositorythis is how many open source projects accept contributionslarge projects in general benefit from using this model over branches,as it restricts who can directly edit the main project, allowing for codereview


Forks

create your own copy of another repositoryhas the benefits of working on separate branches, but with completeindependenceyou may create a pull request between your fork and the originalrepository

this is how many open source projects accept contributionslarge projects in general benefit from using this model over branches,as it restricts who can directly edit the main project, allowing for codereview


Forks

create your own copy of another repositoryhas the benefits of working on separate branches, but with completeindependenceyou may create a pull request between your fork and the originalrepositorythis is how many open source projects accept contributions

large projects in general benefit from using this model over branches,as it restricts who can directly edit the main project, allowing for codereview


Forks

create your own copy of another repositoryhas the benefits of working on separate branches, but with completeindependenceyou may create a pull request between your fork and the originalrepositorythis is how many open source projects accept contributionslarge projects in general benefit from using this model over branches,as it restricts who can directly edit the main project, allowing for codereview


Forks

let’s go fork 2048: https://github.com/gabrielecirulli/2048


https://github.com/gabrielecirulli/2048

Forks

make some changes to the fork

create a pull request on the original repositorydon’t actually submit it if it’s not serious


Forks

make some changes to the forkcreate a pull request on the original repository

don’t actually submit it if it’s not serious


Forks

make some changes to the forkcreate a pull request on the original repositorydon’t actually submit it if it’s not serious


Other GitHub Features

feature rich issue tracker

I anybody may submit issues and commentI people may be assigned to issuesI milestones allow issues to be grouped together with an optional deadline

GitHub flavored markdown (GFM) is an extension of the simplelanguage markdown

I markdown’s philosophy is to have plain text source code, which looksclose to its compiled form

I GFM adds syntax highlighting, as well as allowing you to reference users,repositories, commits, issues, and more, with a simple syntax

I all comments, READMEs, and issues are rendered in markdown

GitHub Pages allows any repository to have its own website

I create a branch named gh-pagesI by default, GitHub assumes this repository contains source code for

Jekyll, a static site generator, and will compile it for youI if you just want to give it plain HTML, just add an empty file to your

repository named .nojekyll



feature rich issue trackerI anybody may submit issues and comment

I people may be assigned to issuesI milestones allow issues to be grouped together with an optional deadline











feature rich issue trackerI anybody may submit issues and commentI people may be assigned to issues

I milestones allow issues to be grouped together with an optional deadlineGitHub flavored markdown (GFM) is an extension of the simplelanguage markdown










feature rich issue trackerI anybody may submit issues and commentI people may be assigned to issuesI milestones allow issues to be grouped together with an optional deadline















I all comments, READMEs, and issues are rendered in markdownGitHub Pages allows any repository to have its own website











I create a branch named gh-pages

I by default, GitHub assumes this repository contains source code forJekyll, a static site generator, and will compile it for you

I if you just want to give it plain HTML, just add an empty file to yourrepository named .nojekyll









Jekyll, a static site generator, and will compile it for you

I if you just want to give it plain HTML, just add an empty file to yourrepository named .nojekyll










repository named .nojekyllDan Wysocki Git and GitHub February 12, 2015 46 / 48

Useful Links

github tutorialhttps://guides.github.com/activities/hello-world/

git game https://github.com/hgarc014/git-game


https://guides.github.com/activities/hello-world/

https://github.com/hgarc014/git-game

Useful Links

github tutorialhttps://guides.github.com/activities/hello-world/git game https://github.com/hgarc014/git-game


https://guides.github.com/activities/hello-world/

https://github.com/hgarc014/git-game

Questions

Any questions?


git and github - suny oswegocs.oswego.edu/~csa/repo/talks/git-talk.pdf · 1 versioncontrol 2 git 3...

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