GitHub Tutorial

by Xiurong Yu

Git vs. GitHub

Git: Keep “snapshots” of code & does not require github
Github: Stores code in the cloud, visually track changes, & requires git.

Initial Setup

- Make a github account.

1. Go to www.github.com
2. Click sign up in the upper right hand corner.
3. Step 1 will ask you to fill in a username, email address, and password you want to use.
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4. Step 2 will ask you to choose a plan.
   • Usually you would choose free plan unless you want to pay for the other one.
5. Step 3 will ask you some question and you will answer them.
6. Click submit once you completed all steps.
7. Go to the email address you put down when signing up to github.
   • You should see a message from github that askes you to verify your email address.
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   • Click on Verify email address and it will bring you to your github account. This means your email address is verified and you are able to access github features!

- SSH Setup

Setting up a SSH key allows you to create a connection with a remote server. In this case, you are trying to create a connection between github and cloud9.

Here are the steps to setting up SSH Key:

1. In your github page, click on profile icon on the upper right hand corner and press settings.
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2. Then on the leftside bar (under personal setting), click on SSH and GPG Keys.
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3. Click New SSH key
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4. Go to your cloud9 account. Click on the gear icon on the upper right.
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5. Click on “SSH Keys” on the left.
6. Copy the 2nd SSH Key to your github account.
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7. Your SSH is now set up!

Repository Setup

- Making a Repository (repo) and initialize git

Directory: Folder

Repository: When git is initialized, folders are called repo

Working Directory: where you’ll be doing all the work: creating, editing, deleting and organizing files

Staging Area: where you’ll list changes you make to the working directory

1. Go to your github account that you have created. On the upper right hand corner, click the “+” sign and create a new respository.
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2. Give your repository a name (In this case I named it tutorial-repo). Once your repository is created, you should be seeing this
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3. Copy the SSH link on github; Make sure it’s the SSH link, not HTTP
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4. Go to your cloud9 account. On a new terminal/workspace and type in the following and paste the link after git clone.
   git clone [link]

git clone: Creates a copy of a repo to a directory. In this case, we are cloning the remote repo (from github) to local workspace (in cloud9).

1. Everytime you clone something, always cd into it
   cd [name of the repo]

cd: Change directory (allows you to move into the directory you want to be in).

1. Make a file in this repo and name it README.md (this will help you practice git add & git commit later on) touch README.md

touch: makes a new file

1. Now initialize git inorder to use git commands
   git init
   • You should be seeing something like this

     username:~/workspace/reponame (master) $
     

git init: Creates a new, empty git repository. This is where git commands are allowed to be used

• Note: Do not ever git init in workspace because it is an empty git repository.

Error Handling

• If you already initialize it, rm -rf .git will help you remove it.
  • rm -rf .git: Removes the .git repository completely (Undo git init)
  • Notice the (master) is gone when you uninitialize git.
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- First add and commit

1. Go to the readme file you creaded in cloud9 (the one you cloned from github)
   cd [your repo]

2. Open up the README.md file you created inside this folder and type in any message you want.
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3. Now go back to the command line, and add this file to staging area.
   git add README.md"

• Git add: Adds files from the working directory to the staging area. Here are 3 ways you can use git add
  • git add [filename]
  • git add . adds the current directory
  • git add --all includes all changes, including deleted files

1. Once you have added the file, commit it with a message that will help you reference what you did.
   git commit -m "[message]"

Git commit -m: Takes a snapshot of the files on the stage.

• Message should be present tense and should describe the snapshot

1. Now you have to set connection with your remote repo in github in order to push your commits. Use the following format
   git remote add origin [URL]

git remote add origin [URL]: Sets connection with between the local repo and the remote repo, then, give it a short name

• Note: Once you added the remote origin, you no longer have to added next time unless you want the file to go to a diferent remote.
  • you can find the URL under “…push an existing repository from the command line”
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1. Now type the second line of the code
   git push -u origin master

git push -u origin master: allows you to push the changes you made in your local repo to the main branch (master) of the remote repository.

• This is only for the first time set-up; this means the next time you can just use git pushto push into the same repo in github.
  • You should be seeing the following after you push showing that you have successfully pushed your README file on github
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git push: Sends the commit from logo repo to remote repo

1. Go back to your github account, open your repo, then press commits.
   • You should be able to see the commit you just pushed! (For your repo, you should only see one commit)
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Workflow & Commands

If you want to commit another file to github(the remote repository), the process will be different. Let’s commit another message to the same README.md file we’ve been working on.

1. Make sure you are on your repo in a command line (at cloud9)
   • You should see USERNAME: ~/workspace/[name of your repo] $
2. Open up your README.md. You can use the following to help you open. * c9 README.md
3. Add or delete anything in the text go back to your terminal.
4. Now add your file to the staging area
   git add README.md
5. Use git status to check the state of your file
   • You should see README.md in green showiing that it can be commited
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git status: Shows the state of file. Tells you the staged and unstagged file, and files that are not tracked.

1. Now commit the file by stating what you did to the file `git commit -m “[text]”
2. Push the commit to the remote. This time you don’t have to do git remote add origin [URL]or git push -u origin master because it is a one time set-up that is already added. So just simply type git push
   • You should still see something similar to
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3. Now you can go to github and check the commits in your repo. You should now see another commit being added to github!

Rolling Back Changes

undo edit/add/commit/push

- Undo edit

1. Make sure you are in USERNAME:~/workspace/[name of repo]. If not cd into it.
2. Go to your README.md and add some text.

3. Now use git status to check the stage of your file (try to use this command frequently to check your state of file)
   git status

4. Now notice the nessage above the README.md is red because you have not added to the staging area. Also, there are command listed for how to discard a change.
5. Type in this command without using <> or ….
   git checkout -- [file]
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6. Now go open up your README.md
   c9 README.md

7. You should see the texts you added being deleted.

- Undo add

1. Make sure you are in USERNAME:~/workspace/[name of repo]. If not cd into it.
2. Make some changes to your README.md.
3. On the terminal, add your README.md to the staging area. git add README.md
4. Your README.md should be showing up as green because it is being added to the staging area.
5. Now Check the state of your files git status
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6. Since your README.md is green, you want to unstage it (turn it to red) using the command given above
   git reset HEAD README.md

7. Now use git status, and you should be seeing your README.md unstaged (red).

- Undo commit

1. Following from the step above, add README.md to the staging area. git add README.md
2. Your README.md should appear green. Now commit it with a message. `git commit -m “[text]”
3. You have just commited README.md, but you want to undo it. Use the following to help you undo the commit.
   git reset --soft HEAD~1
4. You have just undo your commit!

- Undo Push

1. Make sure you are in USERNAME:~/workspace/[name of repo]. If not cd into it.
2. Add some text to README.md
3. Add and commit it
4. Then git push. This will allow you to see your commits in the remote repo.
5. At this point, you realized that you did not mean to push it and you want to undo your push. Use the following to undo a push.
6. First use git log to view the history of your commits.
7. Copy the SHA of the commit you want to delete (something like b2322f7df4ada74a0681beb121e6b933fe6b021)

8. Then git revert [SHA]
   git revert: undoes a commited snapshop

9. Once you git revert, a page will pop up
10. Then press control X to exit.