| title | author | date |
|---|---|---|
Git & GitHub |
Wyoming IBC |
October 7, 2019 |
1.4 A Typical Authentication Session
1.5 Notify Your Computer About the Keys
1.6 Add SSH Keys to Your GitHub Profile
1.7 Create a New Repository on GitHub
1.8 Upload Your Local Repo to GitHub
Git is a version control system. Don't let that make you feel like you are a software engineer. You don't have to be one for it to be useful to you. In the simplest terms, git keeps a journal of all the changes you will make to any files and folders (create, edit, copy, move, delete etc.) in a given project. Think of it as a virtual assistant that is always listening and keeping track of what you do.
GitHub as you probably already figured out, is an online resource that allows people to host and archive their code. The code can be updated/maintained from multiple computers that you may have access to. You may keep it all to yourself, share it with collaborators or if its useful enough, share it with the community at large. Code is divided into repositories on GitHub and you may have one or a hundred each dedicated to a different project you are working on. Consider that you are teaching a course for which you may host the weekly materials such as presentations, assignments and exam solutions to a GitHub repository and then share the repo with your students.
As you can see, one doesn't really need to be a software programmer for Git and GitHub to be useful to them. With this introduction, we are barely scratching the surface. In the Further Reading section below, you will find additional resources to learn about these tools. For now, we will set up your environment so it's usable today.
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Note For Windows Users: Please install git from https://gitforwindows.org/
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Open the commandline terminal on your system. For Windows, right click and choose Git Bash. For Mac, search for
terminalin the spotlight search.
- Check whether
gitis working on your system:
git --version
git version 2.20.1 (Apple Git-117)
- To check git's documentation i.e. help manual
man git
- To exit the interactive documentation
q- Check the Status of the current directory where your prompt is located:
git status
fatal: not a git repository (or any of the parent directories): .git
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You haven't created any
gitrepositories yet on your system, so this warning message is to be expected. -
Let's create a new repository for testing purposes. First, check where you are on the system, then create a new folder named
gitproject.
pwd
/Users/wyoibc
mkdir gitproject
cd gitproject
pwd
/Users/wyoibc/gitproject
- Initiate a new repository
git init
Initialized empty Git repository in /Users/wyoibc/gitproject/.git/
- Check the status again
git status
On branch master
No commits yet
nothing to commit (create/copy files and use "git add" to track)
- This is normal as well since we haven't yet created any content in here. Now let's go ahead and create a new file.
touch README.md
vim README.md
- Create some content in the file
---
title: Learning the Basics of Git
author: Wyoming IBC
date: October 7, 2019
---
This is a new repository.
- Save the changes and exit
:wq
- Now check the git status again
git status
On branch master
No commits yet
Untracked files:
(use "git add <file>..." to include in what will be committed)
README.md
nothing added to commit but untracked files present (use "git add" to track)
- As you can see, Git is now aware of the changes you made to this repository. It knows that there is a new file, although the file is not yet on Git's roll call. This is by design. Often times, you don't want every file/folder to be tracked by git. So git only tracks changes in files when you ask it to. Let's go ahead and do that.
git add README.md
git status
On branch master
No commits yet
Changes to be committed:
(use "git rm --cached <file>..." to unstage)
new file: README.md
- The next logical step here is to
committhis file to git and then push the contents of the repository to your GitHub account. But before we get there, we need to do a couple of preparations:
SSH translates into Secure SHell which allows for encrypted communication over the network between two computers. What are keys then you might ask? They are secure passwords, usually a very long alphanumeric sequence of characters. Notice the plural. Why keys? That's because in the world of encryption, there are two keys:
- A private key (known only to you)
- A public key (that you can share with others) as a token of your identity.
You can use this pair of SSH keys while communicating with remote computing systems so as to identify yourself over an encrypted network. For example, you an enhance and automate your workflow with the GitHub account through the use of SSH keys. So how does it work?
- First, create a pair of SSH-keys; use the email address associated with your GitHub account:
ssh-keygen -t rsa -b 4096 -C "user@email.com"
Generating public/private rsa key pair.
Enter a file in which to save the key (/Users/wyoibc/.ssh/id_rsa): [Press enter]
A private ssh-key is should be secured with a passphrase, which you will be asked to create. Think of this as a strong password to safeguard your private ssh-key. Make this passphrase strong and secure, and write it down on a post-it or in your notebook somewhere.
Enter passphrase :
Enter same passphrase again:
Your keys have now been stored in the location you chose above e.g. /Users/wyoibc/.ssh. Let's go there and check to make sure.
cd /Users/wyoibc/.ssh/
ls -lh
-rw------- 1 wyoibc inbre 1.7K Oct 07 2019 id_rsa
-rw-r--r-- 1 wyoibc inbre 406B Oct 07 2019 id_rsa.pub
- Key ending in
.pubis your public key which you can share with a remote server. But what's inside it?
cat id_rsa.pub
ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEA6UJHt+SrbvC2K/E/FozdqrsScVYZmdv476b4A/4takitEXEDjorzXWAHcMHSP/pu3VPlZv6G5s04QkXYRMYxpb3c+LY+7+I39i6aYtGbbkx+HiLIGXDw5R5Pqlh+aSec1ndEXv5aK5yWghMDpOmaq4K+rrhd70zRem28+uUhZeCocJxr56ORIHhBAI84ZKrk2tOnuaD8ad4AKoidM1y9CHRPRB3HzgmaEvO3YzZgiM5A83EkSHpmR1lZnFBvAibX6+lJNYMHwy3fsuxDml1GpDNUCTesSkzQX7L+MBppuylm358vW7xyGdZP245kLYNwqja5nRKprL2uC9rwmQ3T6Q== wyoinbre@gmail.com
- What about the private key?
cat id_rsa
-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC,4CC25AF5303CA059
---
---
---
-----END RSA PRIVATE KEY-----
So how do these keys work together allow secure communication with a remote server?
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The public key is shared with the server you are trying to communicate with.
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When you try to connect to the server, it looks at your public key, and sends a manifest to your computer. Your computer then checks your public key against the private key and if they match, notifies the server that you are who you say you are.
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Server logs you in or allows file/data transfer.
There is an SSH agent on your system which needs to be notified of the presence of ssh keys. This is a two step process:
- First create a configuration file named
config
cd /Users/wyoibc/.ssh
vim config
- Add the following lines to your newly created config file. Pay attention to the upper and lowercase letters.
Host *
AddKeysToAgent yes
UseKeychain yes
Host YOUR_GITHUB_USER_NAME.github.com
HostName github.com
User git
PreferredAuthentications publickey
IdentityFile /Users/wyoibc/.ssh/id_rsa
- Second, notify the ssh agent
ssh-add -h
ssh-add: illegal option -- h
usage: ssh-add [options] [file ...]
Options:
-l List fingerprints of all identities.
-E hash Specify hash algorithm used for fingerprints.
-L List public key parameters of all identities.
-k Load only keys and not certificates.
-c Require confirmation to sign using identities
-m minleft Maxsign is only changed if less than minleft are left (for XMSS)
-M maxsign Maximum number of signatures allowed (for XMSS)
-t life Set lifetime (in seconds) when adding identities.
-d Delete identity.
-D Delete all identities.
-x Lock agent.
-X Unlock agent.
-s pkcs11 Add keys from PKCS#11 provider.
-e pkcs11 Remove keys provided by PKCS#11 provider.
-q Be quiet after a successful operation.
-A Add all identities stored in your keychain.
-K Store passphrases in your keychain.
With -d, remove passphrases from your keychain.
- Check what the ssh agent has in its memory
ssh-add -l
The agent has no identities.
- Good! Let's add our identity
ssh-add /Users/wyoibc/.ssh/id_rsa
Enter passphrase for /Users/wyoibc/.ssh/id_rsa:
Identity added: /Users/wyoibc/.ssh/id_rsa (/Users/wyoibc/.ssh/id_rsa)
- Check the memory one more time
ssh-add -l
2048 SHA256:ZtqsHDh1QDAKDIKzQ4J4FYlnSGi3Di17mlJzakGtxF4 /Users/wyoibc/.ssh/id_rsa (RSA)
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Navigate to https://github.com/YOUR_USER_NAME
-
Then follow these steps:
Give your key whatever name you'd like, but don't use spaces or special characters in that name. Then paste the contents of your id_rsa.pub in the provided box. Then save. Your saved key should appear like this:
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Follow on screen instructions for creating a new repo called
gitproject -
Make sure not to initialize the repo with a README
-
Once the repo is generated, use the following procedure for uploading your local work to GitHub
- First go to the repository where you had created a README.md file
cd /Users/wyoibc/gitproject
cat README.md
---
title: Learning the Basics of Git
author: Wyoming IBC
date: October 7, 2019
---
This is a new repository.
- Check git status
git status
On branch master
No commits yet
Changes to be committed:
(use "git rm --cached <file>..." to unstage)
new file: README.md
- Configure git to use your github credentials
git config user.name "YOUR GITHUB USER NAME" ## Keep the quotes
git config user.email "YOUR EMAIL ASSOCIATED WITH GITHUB" ## Keep the quotes
- Check your settings
git config --list
user.name=wyoibc
user.email=wyoinbre@gmail.com
- Now we are good to upload; First, commit the README.md to git
git commit -m "A helpful note about your changes" ## You could say something like "Initial commit"
- Tell git your repository's name
git remote add origin git@github.com:wyoibc/gitproject
- Finally push changes
git push -u origin master
- Ideally, you should see something like the following:
Enumerating objects: 3, done.
Counting objects: 100% (3/3), done.
Delta compression using up to 8 threads
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), 328 bytes | 328.00 KiB/s, done.
Total 3 (delta 0), reused 0 (delta 0)
To github.com:wyoibc/gitproject
* [new branch] master -> master
Branch 'master' set up to track remote branch 'master' from 'origin'.
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This indicates that the repo was successfully synced with GitHub. Go to GitHub and check it out:
