https://help.github.com/en/articles/adding-an-existing-project-to-github-using-the-command-line

Create a new repository on GitHub
https://github.com/test-user?tab=repositories

Open terminal and change the current working directory to your local project

1. git init
2. git commit -m “first commit”
3. git remote add origin git@github.com:test-user/test_project.git
4. git push -u origin master

In step 3 the URL can be obtained from the GitHub repositories Quick Setup page. Copy the ssh link which has this format: git@github.com:test-user/test_project.git

(Do not use the https url. You will be asked to enter username and password with the https url)

verify new remote url git remote -v

    git clone <remote_repo>

    git clone -b <branch> <remote_repo>

Example

        git clone -b develop git@github.com:user/myproject.git

https://coderwall.com/p/y7hf6w/how-to-clone-a-specific-branch-in-git

pull from remote branch (master) to local (origin)

git pull origin master

push from local branch (origin) to remote branch (master)

git push origin master

create new branch

git checkout -b test-branch-1

switch to another branch

git checkout test-branch-2

push a new local branch to remote git repository

git push -u origin test-branch-2

pull from remote branch (test-branch) to local (origin)

git pull origin test-branch

push from local branch (origin) to remote branch (test-branch)

git push origin test-branch

merge local branch with master:

git checkout master
git pull origin master
git merge test-branch

rename local branch

if you are on the branch you want to rename:

    git branch -m new-name

if you are on a different branch

    git branch -m old-name new-name

delete file from git repository

git rm file.txt

delete directory from git repository

git rm -r folder-name

create git branch from another branch

If you want to create a new branch branch2 from existing branch branch1

git checkout branch1
git checkout -b branch2 branch1 

merge two local branches

https://stackoverflow.com/questions/25053697/git-merge-two-local-branches/25053738 If you have branch Master, branch1 and branch2. To merge branch2 into branch1

git checkout branch1
git merge branch2

git add all

Stage all files in your repository, which includes all new, modified and deleted files.

git add -A

or

git add --all

Add all files under folder vendor

git add -A vendor

undo git add

git reset <file_name>

undo all files that were added

git reset	

remove all local untracked files

remove all local untracked files (local changes that have not yet been commited) from a dir, so only git tracked files remain

git clean -fd <some-dir>

options:
-d  recurse into untracked directories. -d is irrelevant if any paths are specified.
-f  --force
-i  --interactive Show what would be done and clean files interactively
-n  --dry-run show what would be done. Don't actually remove anything

revert uncommited changes

Revert uncommitted changes only to particular file or directory:

git checkout [some_dir|file.txt]

undo file delete

git checkout HEAD <filename>

Restoring file delete: https://www.git-tower.com/learn/git/faq/restoring-deleted-files/

Delete local branch

The local branch should not be current while deleting it. Switch to some other branch before deleting it.

git branch -d <branch_name>

Delete remote branch

git push origin --delete <branch_name>

Show history of changes on a file

git annotate <file-name>

Change commit message (when commit has not been pushed online)

git commit --amend

press Enter. In the vi editor edit the commit message and save

See the remote repository your project is pointing to

git remote -v

Stage a file for removal

file is not removed from the working dir. The file will then be shown as untracked.

untrack all files
    git rm -r --cached .
     
untrack specific file
    git rm --cached foo.txt

Remove all version tracking from a projrcts directory

rm -rf .git

Find hash of branch

git rev-parse <branch>

example: 
    git rev-parse master
    17f2303133734f4b9a9aacfe52209e04ec11aff4

Revert a git merge (link)

Example: 
1. find hash of the branch you want to revert 
    git rev-parse master
    17f2303133734f4b9a9aacfe52209e04ec11aff4

2. Use the hash to revert a merge
    git revert -m 1 17f2303133734f4b9a9aacfe52209e04ec11aff4

Push your static website to a git repository

Go to the settings page of your repository and scroll to the bottom where it says Danger Zone. Change the visibility to public. 

Scroll down to the GitHub Pages section and chose the source branch. (example - master). Select folder root and click "Save" button.

A message with a url where your site is published at will appear under the GitHub Pages section of the settings page.

Enter the URL link in a browser to launch your static website.