Git at first glance

As a distributed source version control system, Git is a quite complicated.
There are several components you will usually get touch with while using Git.

Following is the very basic architecture of components you will use:

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Local Machine

Pretty self-explanatory, local machine means the local machine than you are directly coding on or using. For example if you are coding in a remote server through SSH, that remote server is also called local machine, as that is the computer that you use to do the work directly.

Several components exist in local machine:

Working directory

Working directory, is the most trivial conception of coding. Why? say, you modify a file README.md with vim, then save it by :x, now this README.md file definitely in Working directory.
Files in working directory have 2 state:

Untracked

Files that are newly created and have never been versioned by Git.
A fresh created file should be an untracked file, and the way to ask Git to take care of this file is

git add FILE_NAME

This command tells Git, Go to take care of that guy...
Once ever the file is traced by git add, git started to aware of the content change of this file.

Tracked

Files that have been versioned by Git.
Git will monitor which file is modified, deleted and renamed.
Add untracked files or modify tracked files would trigger this mechanism, use git status to see the changes you made since last commit.

Staging area

If you want to use Git to save files, you need to first store the current state in an area called Staging area. There are several way to achieve this:

1. Use git add FILE_NAME to add files that already exist
2. Use git rm FILE_NAME to delete a file that is being tracked
3. Use git mv ORIGIN_NAME DEST_NAME to move or rename a file. This usage is exactly same with the Linux command mv

You need to place any file that you want to commit into this area, including files that you want to delete and move.

Stash area

This area will not be used very often, only when you want to do some operations about original commits without affecting files in working directory.
We usually use this area when we switch branch, pull commit. Operations like these will probably mess up you working directory.
To avoid this, you can store working directory temporarily in stash.

git stash

After finishing your operation, you want to resume your work,

git stash pop

Local repository

Now you want to save the changes permanently, let’s do the commit

git commit -m"COMMIT_MESSAGE"

All files in staging area will be saved permanently after commiting.
You can find the local commit log by using:

git log

And you can have better printing and format by:

git log --color --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit --

Remote ref

This is the local references of remote host.
This is to compare the relative relationship between real remote repository and you local repository.
This ref will be synchronized whenever fetch and pull.

git fetch

Remote repository

A remote repository is a git repository where you will not do the code directly on it.
The purpose of this repository is to store you local commit in a distributed fashion.
Technically speaking, after commiting locall, your local machine still has the risk of disk failure.
To avoid this tragedy, we need a remote repository to save our code.

git push # push your code to remote repository
git pull # pull the code from remote repository to local repository