Git is the most widely used modern version control system.  When you learn git, you may encounter issues to master all the git commands.  In this tutorial, we list the essential git commands. After master these commands, you can use git to accomplish most of the version control tasks. 

The following two diagrams show how git manages your files.

The four stages of a file in git

1. Create a Repository
   Create a new local repository from scratch
   git init [my_project] or cd my_project git init

   1 2 3 4 5 6

   git init [my_project]   or   cd my_project git init

   Download from an existing repository

   git clone remote_reposity_url_on_github

   1	git clone remote_reposity_url_on_github

2. Check your repository
   List the files that have not been committed 
   git  status

   1	git  status

   Show the changes to files not staged

   git diff

   1

   git diff

   Show full change history

   git log

   1

   git log

   Show more detailed change history

   git reflog

   1	git reflog

   show the changes between two commits ids

   git diff commit_id1 commit_id2

   1	git diff commit_id1 commit_id2

3. Git Branches
   List all local branches
   git branch                     

   1	git branch

   List all local and remote branches

   git branch -av            

   1	git branch -av

   create a new branch

   git branch my_branch_name    

   1	git branch my_branch_name

   Switch to a branch

   git checkout my_branch_name

   1	git checkout my_branch_name

   create a new branch using an old branch and switch to the new branch

   git checkout old_branch_name git checkout -b new_branch_name or git checkout old_branch_name git branch new_branch_name git checkout new_branch_name

   1 2 3 4 5 6 7

   git checkout old_branch_name git checkout -b new_branch_name   or git checkout old_branch_name git branch new_branch_name git checkout new_branch_name

   delete a local branch

   git branch -d branch_name

   1	git branch -d branch_name

   delete a remote branch

   git push origin :{the_remote_branch} or git push origin --delete the_remote_branch

   1 2 3

   git push origin :{the_remote_branch} or git push origin --delete the_remote_branch

   tag a branch

   git tag my_tag

   1	git tag my_tag

   merge branch_a to branch_b

   git checkout branch_b git merge branch_a

   1 2	git checkout branch_b git merge branch_a

4. Add files to repository and do commit
   Add a single file to index,