SSH access to Github from multiple accounts

• Generate SSH Keys:

  ssh-keygen  -t rsa -b 4096 -C "email@personal.com" -f ~/.ssh/id_rsa_personal
  ssh-keygen  -t rsa -b 4096 -C "email@work.com" -f ~/.ssh/id_rsa_work
  

  The two commands above generate two key pairs: id_rsa_personal/id_rsa_personal.pub, id_rsa_work/id_rsa_work.pub. 
• Add SSH Keys to your github accounts.
• Add id_rsa_personal.pub to your personal github account:
• Login to your github
• Go to Settings -> Add SSH Keys
• Copy of the content of id_rsa_personal.pub to the key field
• Click Add Key
• Add id_rsa_work.pub to your github account for work:
• Login to your github
• Go to Settings -> Add SSH Keys
• Copy of the content of id_rsa_work.pub to the key field
• Click Add Key
• Create a file: ~/.ssh/config and add:

Host personal
   HostName github.com
   User git
   IdentityFile ~/.ssh/id_rsa_personal

Host work
   HostName github.com
   User git
   IdentityFile ~/.ssh/id_rsa_work
• Update stored identities:

ssh-add -D
ssh-add id_rsa_personal
ssh-add id_rsa_work

• Test

ssh -T personal
Hi githubPersonal! You've successfully authenticated, but GitHub does not provide shell access.
$ ssh -T work
Hi githubWork! You've successfully authenticated, but GitHub does not provide shell access.

Github: Use Access Token to authenticate over HTTPS

• Login to Github
• If you have not enabled Two-factor authentication, you need to enable it:
  • Go to "Settings" -> "Security"
• Generate Personal Access Tokens:
  • Go to "Settings" -> "Personal Access Tokens"
• Click "Generate new token" at the top right corner.
• Remember/Copy the token.
• Insert the token to your repository url:

  https://<token>@github.com/owner/repo.git

• Now you can push to the repository without typing username & password.

Github: fork a repository and sync the fork

1. Fork a repository
   • Clone the repository:

     git clone https://github.com/ORIGINAL_OWNER/ORIGINAL_REPO.git

   • Add the original repository as upstream:

     git remote add upstream https://github.com/ORIGINAL_OWNER/ORIGINAL_REPO.git

   • Check the status:

     git remote -v

     You will see:

     # origin    https://github.com/YOUR_USERNAME/YOUR_FORK.git (fetch)
     # origin    https://github.com/YOUR_USERNAME/YOUR_FORK.git (push)
     # upstream  https://github.com/ORIGINAL_OWNER/ORIGINAL_REPO.git (fetch)
     # upstream  https://github.com/ORIGINAL_OWNER/ORIGINAL_REPO.git (push)
     

2. Sync the fork with upstream(original):
   • Fetch the branches and their respective commits from the upstream repository:

     git fetch upstream

   • Check out your fork's local master branch:

     git checkout master

   • Merge the changes from upstream/master into your local master branch. This brings your fork's master branch into sync with the upstream repository, without losing your local changes.

     git merge upstream/master

   • Push local repository:

     git push --tags