Learn Git_Lesson_Git Teamwork

1.Overview
Git offers a suite of collaboration tools to make working with others on a project easier.
Imagine that you're a science teacher, developing some quizzes with Sally, another teacher in the school. You are using Git to manage the project.
In order to collaborate, you and Sally need:

• A complete replica of the project on your own computers
• A way to keep track of and review each other's work
• Access to a definitive project version

You can accomplish all of this by using remotes. A remote is a shared Git repository that allows multiple collaborators to work on the same Git project from different locations. Collaborators work on the project independently, and merge changes together when they are ready to do so. 2.git clone
Sally has created the remote repository, science-quizzes in the directory curriculum, which teachers on the school's shared network have access to. In order to get your own replica of science-quizzes, you'll need to clone it with:

git clone remote_location clone_name

In this command:

• remote_location tells Git where to go to find the remote. This could be a web address, or a filepath, such as:

/Users/teachers/Documents/some-remote

• clone_name is the name you give to the directory in which Git will clone the repository.

 The Git remote Sally started is called:

science-quizzes

Enter the command to clone this remote. Name your clone:

my-quizzes

Notice the output:

cloning into 'my-quizzes'...

Git informs us that it's copying everything from science-quizzes into the my-quizzes directory.
my-quizzes is your local copy of the science-quizzes Git project. If you commit changes to the project here, Sally will not know about them.$ git clone science-quizzes/ my-quizzes                                                          

Cloning into 'my-quizzes'...                                                                     

done.3.git remote -v
We have a clone of Sally's remote on our computer. One thing that Git does behind the scenes when you clone science-quizzes is give the remote address the name origin, so that you can refer to it more conveniently. In this case, Sally's remote is origin.
You can see a list of a Git project's remotes with the command:

git remote -v

3.1.Using the file navigator, examine the contents of the cloned Git project. There are a few quiz files here, which we will be working with during this lesson.
Open a file of your choice in the code editor.

3.2.Change directories into the my-quizzes directory, enter this command on the terminal:

cd my-quizzes

3.3.list the remotes. 

$ git remote -v                                

origin  /home/ccuser/workspace/curriculum/science-quizzes/ (fetch)                            

origin  /home/ccuser/workspace/curriculum/science-quizzes/ (push)  

• Git lists the name of the remote, origin, as well as its location.
• Git automatically names this remote origin, because it refers to the remote repository of origin. However, it is possible to safely change its name.
• The remote is listed twice: once for (fetch) and once for (push).

4.git fetch
After you cloned science-quizzes, you had to run off to teach a class. Now that you're back at your computer, there's a problem: what if, while you were teaching, Sally changed the science-quizzes Git project in some way. If so, your clone will no longer be up-to-date.
An easy way to see if changes have been made to the remote and bring the changes down to your local copy is with:

git fetch

This command will not merge changes from the remote into your local repository. It brings those changes onto what's called a remote branch.
4.1.go into the my-quizzes directory.
$ cd my-quizzes  
4.2.Fetch any new changes Sally may have made to the remote.  

$ git fetch                                                                                      

remote: Counting objects: 6, done.                                                               

remote: Compressing objects: 100% (5/5), done.                                                   

remote: Total 5 (delta 1), reused 0 (delta 0)                                                    

Unpacking objects: 100% (5/5), done.                                                             

From /home/ccuser/workspace/curriculum-a/science-quizzes                                         

* [new branch]      master     -> origin/master    
5.git merge
Even though Sally's new commits have been fetched to your local copy of the Git project, those commits are on the origin/master branch. Your local master branch has not been updated yet, so you can't view or make changes to any of the work she has added.
In Lesson III, Git Branching we learned how to merge braches. Now we'll use the git merge command to integrate origin/master into your local master branch. The command:

git merge origin/master

will accomplish this for us.
5.1.go into the my-quizzes directory

cd my-quizzes

You are on your local master branch. In your commit history, the commit message of the HEAD commit is:

Add first question to Physics     quiz

From the terminal, merge with origin/master, where Sally's most recent commits are.
Notice the output:

$ git merge origin/master                                                                        

Updating 2fd7d9b..3a29454                                                                        

Fast-forward                                                                                     

 biology.txt | 4 ++++                                                                            

 1 file changed, 4 insertions(+)                                                                 

 create mode 100644 biology.txt 

Print the commit history.
In the output, notice that the HEAD commit has changed. The commit message now reads:

Add heading and comment to biology quiz

$ git log                                                                                     

commit 3a294546f4a55f02bf37233ef8988d8b9dd7ce59                                                  

Author: danasselin <johndoe@example.com>                                                         

Date:   Tue Nov 3 12:33:23 2015 -0500                                                                                                                                                            

    Add heading and comment to biology quiz                                                                                                                                                      

commit 6aa7704a31d05541141fbb529abf946bd2fd416b                                                  

Author: danasselin <johndoe@example.com>                                                         

Date:   Thu Oct 29 17:04:04 2015 -0400                                                                                                                                                           

    Add biology quiz                                                                                                                                                                             

commit 2fd7d9b248e0b4a3b531b9af3bb61916d42ad45f                                                  

Author: danasselin <johndoe@example.com>                                                         

Date:   Thu Oct 29 15:42:55 2015 -0400                                                                                                                                                           

    Add first question to physics quiz                                                                                                                                                           

commit 2c4e484e0f5bda111a164e6580f4a4a603cea48f                                                  

Author: danasselin <johndoe@example.com>                                                         

Date:   Thu Oct 29 15:42:36 2015 -0400                                                                                                                                                           

    Add physics quiz                                                                                                                                                                             

commit 65be0d3f24fb34363bdac6949325f35ad3cdd98a                                                  

Author: danasselin <johndoe@example.com>    

Date:   Thu Oct 29 15:42:21 2015 -0400                                                                                                                                                           

    Add chemistry quiz                                                                                                                                                                           

commit 9bfc082a0e64efe5c0a2e4298e0b4f127d0a9b96Git has performed a "fast-forward" merge, bringing your local master branch up to speed with Sally's most recent commit on the remote.
6.git workflow
Now that you've merged origin/master into your local master branch, you're ready to contribute some work of your own. The workflow for Git collaborations typically follows this order:

1. Fetch and merge changes from the remote
2. Create a branch to work on a new project feature
3. Develop the feature on your branch and commit your work
4. Fetch and merge from the remote again (in case new commits were made while you were working)
5. Push your branch up to the remote for review

Steps 1 and 4 are a safeguard against merge conflicts, which occur when two branches contain file changes that cannot be merged with the git merge command. Step 5 involves git push.
6.1.change directories into the my-quizzes directory. 
6.2.Create a branch to develop questions for the biology quiz. Name the branch bio-questions.

$ git branch bio-questions 
6.3.Switch to your new branch

$ git checkout bio-questions                   

Switched to branch 'bio-questions'6.4.On your branch, open biology.txt in the code editor.
Add a biology question to the file and some sample answers.
6.5.Add biology.txt to the staging area.
$ git add biology.txt  
6.6.Commit the work to the repository with a commit message.

$ git commit -m "First Commit"                 

[bio-questions fcc7550] First Commit           

 1 file changed, 5 insertions(+)  

7.git push

git push origin your_branch_name

will push your branch up to the remote, origin. From there, Sally can review your branch and merge your work into the master branch, making it part of the definitive project version.
7.1.change directories into the my-quizzes directory. 
$ cd my-quizzes/    

7.2.Push your branch up to the remote.

$ git push origin bio-questions                                                                  

Counting objects: 5, done.                                                                       

Delta compression using up to 3 threads.                                                         

Compressing objects: 100% (3/3), done.                                                           

Writing objects: 100% (3/3), 388 bytes | 0 bytes/s, done.                                        

Total 3 (delta 1), reused 0 (delta 0)                                                            

To /home/ccuser/workspace/curriculum-a/science-quizzes                                           

 * [new branch]      bio-questions -> bio-questions
Git informs us that the branch bio-questions was pushed up to the remote. Sally can now review your new work and can merge it into the remote's master branch. 
8.generalizations

• A remote is a Git repository that lives outside your Git project folder. Remotes can live on the web, on a shared network or even in a separate folder on your local computer.
• The Git Collaborative Workflow are steps that enable smooth project development when multiple collaborators are working on the same Git project.

We also learned the following commands

• git clone: Creates a local copy of a remote.
• git remote -v: Lists a Git project's remotes.
• git fetch: Fetches work from the remote into the local copy.
• git merge origin/master: Merges origin/master into your local branch.
• git push origin <branch_name>: Pushes a local branch to the origin remote.

Git projects are usually managed on Github, a website that hosts Git projects for millions of users. With Github you can access your projects from anywhere in the world by using the basic workflow.