If you've got 2FA enabled on your Github account, your regular password won't work for this purpose, but you can generate a Personal Access Token and use that in its place instead.

Visit the Settings -> Developer Settings -> Personal Access Tokens page in GitHub (https://github.com/settings/tokens/new), and generate a new Token with all Repo permissions:

The page will then display the new token value. Save this value and use it in place of your password when pushing to your repository on GitHub:

> git push origin develop
Username for 'https://github.com': <your username>
Password for 'https://<your username>@github.com': <your personal access token>

Here's another option:

Instead of writing

git push origin HEAD

You could write:

git push https://user:pass@yourrepo.com/path HEAD

Obviously, with most shells this will result in the password getting cached in history, so keep that in mind.

Updating your Git configuration file directly (if you do not want to memorize fancy commands):

Open your .git/config file in your favorite text editor. It will be in the folder that you cloned or in the repository that you performed git init in. Go into that repository. .git is a hidden folder, and pressing Ctrl + H should show the hidden folder, (ls -a in terminal).

Below is a sample of the .git/config file. Copy and paste these lines and be sure to update those lines with your Git information.

[user]
        name = Tux
        email = tux@gmail.com
        username = happy_feet

[remote "origin"]
        url = https://github.com/happy_feet/my_code.git
        fetch = +refs/heads/*:refs/remotes/origin/*

Change the URL part with the following format for SSH:

url = git@github.com:happy_feet/my_code.git

(The above formats do not change with various Git remote servers like GitHub or Bitbucket. It's the same if you are using Git for version control):

Note: The SSH way of connecting to a remote Git repository will require you to add your public SSH key to your Git remote server (like GitHub or Bitbucket. Search the settings page for SSH keys).

To know how to generate your SSH keys, refer to: Creating SSH keys

If you have cloned HTTPS instead of SSH and facing issue with username and password prompt on pull, push and fetch. You can solve this problem simply for UBUNTU

Step 1: move to root directory

cd ~/

create a file .git-credentials

Add this content to that file with you usename password and githosting URL

https://user:pass@example.com

Then execute the command

git config --global credential.helper store

Now you will be able to pull push and fetch all details from your repo without any hassle.

For Windows Git users, after running git config --global credential.helper store, if it still prompts for a password, you'd better check where the configuration file is written to, using this command

git config --list --show-origin

In my case, after manually editing configuration file 'C:\Program Files\Git\mingw64\etc\gitconfig', and adding the following text, it worked.

[credential]
    helper = store

This is what worked for me:

git remote set-url origin https://username@github.com/username/reponame.git

Example:

git remote set-url origin https://jsmith@github.com/jsmith/master.git

You need to perform two steps -

1. git remote remove origin
2. git remote add origin git@github.com:NuggetAI/nugget.git

Notice the Git URL is a SSH URL and not an HTTPS URL... Which you can select from here:

List your current SSH keys:

ls -l ~/.ssh

Generate a new SSH key:

ssh-keygen -t ed25519 -C "your_email@example.com"

where you should replace your_email@example.com with your GitHub email address.
When prompted to Enter a file in which to save the key, press Enter.
Upon Enter passphrase (empty for no passphrase) - just press Enter (for an empty passphrase).
List the your SSH keys again:

ls -l ~/.ssh

The files id_ed25519 and id_ed25519.pub should now have been added.
Start the ssh-agent in the background:

eval $(ssh-agent -s)

Add your SSH private key to the ssh-agent:

ssh-add ~/.ssh/id_ed25519

Next output the public key to the terminal screen:

cat ~/.ssh/id_ed25519.pub

Copy the output to the clipboard (Ctrl + Insert).
Go to https://github.com/<your-github-username> and sign in with your username and password.
Click your GitHub avatar in the upper-right corner, and then Settings. In the left pane click SSH and GPG keys. Click the green-colored button New SSH key and paste the public SSH key into the textarea labeled Key. Use a descriptive Title that tells from what computer you will use this SSH key. Click Add SSH key.

If your current local repository was created with http and username, it needs to be recreated it so as to become SSH compatible.
First check to make sure that you have a clean working tree so that you don't lose any work:

git status

Then cd .. to the parent directory and rm -fr <name-of-your-repo>.
Finally clone a fresh copy that uses SSH instead of username/password:

git clone git@github.com:[your-github-username]/[repository-name].git

References:
https://docs.github.com/en/free-pro-team@latest/github/authenticating-to-github/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent
https://docs.github.com/en/free-pro-team@latest/github/authenticating-to-github/adding-a-new-ssh-key-to-your-github-account

For Mac OS

1. Go to your Github Settings -> Developer Settings -> Personal Access Tokens page in GitHub (https://github.com/settings/tokens/new), and generate a new Token with all Repo permissions
2. Search Keychain Access in your mac -> search for github.com -> click Show password then paste the token you just copied.
3. Go to the CLI, it will ask again for username and password, enter your Github username and paste the token as password, and you should be good to go for the rest of the times you are using the CLI.

As of 2021, there is a secure user-friendly cross-platform solution for HTTPS remotes. No more typing passwords! No more SSH keys! No more personal access tokens!

Install Git Credential Manager developed by GitHub (downloads). It supports passwordless in-browser OAuth authentication to GitHub, BitBucket, Azure and GitLab. This means you can enable two-factor authentication on GitHub and the other platforms, greatly improving the security of your accounts.

When you push, you are offered a choice of authentication methods:

> git push
Select an authentication method for 'https://github.com/':
  1. Web browser (default)
  2. Device code
  3. Personal access token
option (enter for default): 1
info: please complete authentication in your browser...

On Linux, a tiny bit of setup is required. The following caches credentials in memory for 20 hours, so you have to authenticate at most once per day.

git-credential-manager-core configure
git config --global credential.credentialStore cache
git config --global credential.cacheoptions "--timeout 72000"

Power users familiar with gnome-keyring or KWallet may prefer to change the credential store to libsecret.

Cosmetic configuration (docs):

1. Prefer choosing authentication method at terminal rather than in GUI (fewer clicks)
2. Always use browser method rather than be asked every time (even fewer keypresses)

git config --global credential.guiPrompt false
git config --global credential.gitHubAuthModes browser

Blockquote

if you experience $ git push code issues requesting for username && password follow the procedure below:

Login to your profile.
Go to settings

click developer settings
->Personal access tokens
--> note: access token
--->Select scopes: checkbox on repo
----> Generate token
-----> Make sure to copy and store it safely if you intend to reuse it.

*** use the generated token as password during pushing code for next 30days ***

***HAPPY CODING***

 # gen  the pub and priv keys
 # use "strange" naming convention, because those WILL BE more than 10 ...
 ssh-keygen -t rsa -b 4096 -C "me@corp.com" -f ~/.ssh/id_rsa.me@corp.com@`hostname -s`

 # set the git alias ONLY this shell session
 alias git='GIT_SSH_COMMAND="ssh -i ~/.ssh/id_rsa.me@corp.com.`hostname -s`" git'

 # who did what when and why
 git log --pretty --format='%h %ai %<(15)%ae ::: %s'

 # set the git msg
 export git_msg='issue-123 my important commit msg'

 # add all files ( danger !!! ) and commit them with the msg
 git add --all ; git commit -m "$git_msg" --author "Me <me@corp.com"

 # finally 
 git push

Check your git version and update. Then will fixed the issue

$ git update-git-for-windows

Update note : we can use this when your PC git version and server git version mismatched.