Git Tutorial

Create a new repository
To create a new directory, open it and perform a
git init

Checkout a repository
To create a working copy of a local repository by running the command
git clone /path/to/repository

When using a remote server, your command will be
git clone username@host:/path/to/repository

Add & Commit
You can propose changes (add it to the Index) using
git add <filename>
git add *

This is the first step in basic git workflow. To actually commit these changes use
git commit -m "Commit message"

Now the file is committed to the HEAD, but not in your remote repository yet.  

Workflow
Your local repository consists of three "trees" maintained by git. the first one is your Working Directory which holds the actual files.
the second one is the Index which acts as a staging area and finally the HEAD which points to the last commit you've made.
        

     






Pushing changes
Your changes are now in the HEAD of your local working copy. To send those changes to your remote repository, execute
git push origin master

Change master to whatever branch you want to push your changes to.

If you have not cloned an existing repository and want to connect your repository to a remote server, you need to add it with
git remote add origin <server>

Now you are able to push your changes to the selected remote server

Branching
Branches are used to develop features isolated from each other. The master branch is the "default" branch when you create a repository. Use other branches for development and merge them back to the master branch upon completion.

Create a new branch named "feature_x" and switch to it using
git checkout -b feature_x

switch back to master
git checkout master

and delete the branch again
git branch -d feature_x

a branch is not available to others unless you push the branch to your remote repository
git push origin <branch>

Update & Merge
To update your local repository to the newest commit, execute
git pull

In your working directory to fetch and merge remote changes.
to merge another branch into your active branch (e.g. master), use
git merge <branch>

In both cases git tries to auto-merge changes. Unfortunately, this is not always possible and results in conflicts. You are responsible to merge those conflicts manually by editing the files shown by git. After changing, you need to mark them as merged with
git add <filename>

Before merging changes, you can also preview them by using
git diff <source_branch> <target_branch>

Tagging
git log    
git whatchanged -n 1
git log --stat
git diff HEAD^ HEAD
git show HEAD~2 HEAD~2
git remote -v //get remote link

Revert local changes

git clean -f -d

git reset --hard
git checkout -- HEAD

git checkout -- <filename>

git reset --hard HEAD~1
git reset --hard HEAD@{1}
HEAD~1 means "go to the commit before the commit that HEAD currently points at",
HEAD@{1} means "go to the commit that HEAD pointed at before it pointed at where it currently points at".
Detailed Here

If you instead want to drop all your local changes and commits, fetch the latest history from the server and point your local master branch at it like this
git fetch origin
git reset --hard origin/master
 
If you want to keep your work and just 'undo' that commit command (you caught before pushing to repo):

git reset --soft HEAD~1

Do not use the --hard flag unless you want to destroy your work in progress since the last commit.
 

To Remove remote commit changes:
To remove git commit after git push:
git reset --hard HEAD~1
git push -f

To switch among the commits, use
"$ git reflog" and then using
"$ git checkout commit_id" jump to specific commit id back and forth

To merge branches
$ git fetch
$ git checkout a (you will switch to branch a)
$ git merge b (this will merge all changes from branch b into branch a)
$ git commit -a (this will commit your changes)
$ git push

To checkout remote branch
Before you can start working locally on a remote branch, you need to fetch it.
To fetch a branch, you simply need to:
$ git fetch origin
This will fetch all of the remote branches for you. With the remote branches in hand,
you now need to check out the branch you are interested in, giving you a local working copy
$git checkout -b test origin/test

To create remote branch
1. First, you create your branch locally
   git checkout -b your_branch
   e.g. git checkout -b master-devel-v8.0
2. Then push it to the remote server
   git push <remote-name> <branch-name>
   e.g. git push -u origin master-devel-v8.0

To delete a remote branch
git push origin --delete <branchName>
e.g. git push origin --delete master-devel-v8.0

To delete Local Branch
git branch -D <branchName>
e.g. git branch -D master-devel-v8.0

To create development branch from master
1. first checkout master
2. then checkout devel

To create development branch from master
If two people are working on same branch in git
1. First should commit and push his changes. Then
2. Second should commit his changes and pull first's changes from server and then push everything.

To rebase branch:
1. First checkout working branch
2. Then, rebase from master branch
e.g. git checkout mutex
       git rebase component-integration

To changes of a file in all commit:
git log -p -- path/to/file 

Useful Hints:

built-in git GUI

gitk

use colorful git output

git config color.ui true

show log on just one line per commit

git config format.pretty oneline

use interactive adding

git add -i

https://stackoverflow.com/questions/8801729/is-it-possible-to-have-different-git-config-for-different-projects

https://stackoverflow.com/questions/4523496/is-it-possible-to-pull-from-one-repo-and-push-to-other-one

http://gitref.org/creating
http://git-scm.com/book
http://rogerdudler.github.io/git-guide/
http://www.vogella.com/articles/Git/article.html
http://stackoverflow.com/questions/2745076/what-is-the-difference-between-git-commit-and-git-push
http://www.cyberciti.biz/faq/appy-patch-file-using-patch-command

https://remarkablemark.org/blog/2018/10/09/git-checkout-clean-reset/