# git 指令介紹

## Repository (數據庫)
### What is "Repository" ?
The repository tracks all changes made to files in your project,
building a history over time.

--

### The categories
* Remote repository - everyone with the permission could use it
* Local repository - a user use in the local computer

--
### The intro of the Working tree and index
#### What is "Working tree" ?

The working tree (working directory), consists of files that you are currently working on.

#### What is "index" ?

The index (staging area), is where commits are prepared.
The index compares the files in the working tree to the files in the repository.
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## Git init and basic commands: commit, push, clone and pull
### First step of the git flow
1. create a directory

    mkdir dir_local
    // create a directory

2. go to the directory ( where we need to put our local repository in)

    cd dir_local
    // go to the directory

3. **initiate our local git repository**

    git init
    // Initialized empty Git repository in "dir_local"/.git/

### Commit
#### Introduction
Commit set a message about the changes you were done. The commit also saves a revision of the code and you can revert the code to any version anytime in one click.


#### The steps
1. use add before commit

    git add "certain file"
    // if we need to change the status of certain file (modify/add/delete)

    git add .
    // if we need to change all of the file we edited (modify/add/delete)

2. commit our file

    git commit -m "<The details fo the revision>" 
    // we need to also send a message 

3. check the status of the current action [optional]

    git status
    // check the status of "commit"...

4. check the histrory

* command:

`git log`

* output:

        commit b6c3c771cd8939bcd25a8c50089fdf0cd3eab98d (HEAD -> master)
        Author: 您的姓名 <您的 Email>
        Date:   您的版本更新時間

            新增網頁

### Push
#### Introduction
To upload local repository content to a remote repository.
#### Command
1. prepare where (what remote repository) you want to push to

    git remote add <nickname of the remote repository> <remote url>
    // remote repository with nick-name

2. upload (push) local repository to remote repository

    git push origin master
    // origin is the nickname of the remote repository
    // master is the default branch name of the remote repository

### Clone
#### Introduction
To target an existing repository and create a clone, or copy of the target repository.

**Timing:** when we see this project for the first time (never download from the remote repository )


#### Command
1. select directory
`cd <dir_clone>`

2. clone
`git clone <remote copied url>`

### fetch
#### Introduction
Downloads commits, files, and refs from a remote repository into your local repository.

**Timing:** when we want to update our local repository to the latest version.

Before:

After:

#### Command
`git fetch`

### Pull
* pull = fetch + merge
#### Introduction
To fetch and download content from a remote repository and immediately update the local repository to match that content. And it will also merge the content with the local repository.

#### Command

merge(fast-forward) version:
`git pull`

merge(no fast-forward) version:
`git pull --no-ff`

rebase version:
`git pull --rebase`

* Hint: if you don't know what is merge or rebase, you could check the next topic down below
___

## Branch
### The categories
* Integration branch - the released version
* Topic branch - Fix bugs / add functions ...

### Head
#### Introduction
The pointer to the current branch reference
#### use reset with HEAD
reset : means "go to"
* ^ means previous

git reset HEAD^
// reset what previous HEAD point to

* ~ means "specify the parents of the first generation"
(指第幾代的父代)

git reset HEAD~1
// = git reset HEAD^

### Merge
#### Introduction
Lets you take the independent lines of development created by git branch and integrate them into a single branch.
#### The categories
* Fast forward:
merge one commit with a commit that can be reached by following the first commit’s history (update the HEAD pointer in such a way that its new value is a direct descendant of the prior value. )

**Timing:** when you want to simplify the "commits"

* no fast forward:
creates a new commit with multiple parents, and provides a better history tracking. Otherwise

**Timing:** when you want to have a clear notion of your feature branch.
#### Command
1. change to another branch

`git checkout another_branch`
2. merge the branch -v1 (fast forward by default)

`git merge want_to_merge_branch`
3. merge the branch -v2 (no fast forward)

`git merge want_to_merge_branch --no-ff`

### Rebase
#### Introduction
The process of moving or combining a sequence of commits to a new base commit. (its like copy the sequence of commits to the a new base commit)
#### What is base?
The base of the branch is the commit it grew out of.

#### Command
1. change to another branch

`git checkout another_branch`
2. rebase the branch

`git rebase want_to_merge_branch`

___
Reference:
https://backlog.com/git-tutorial/tw/
https://w3c.hexschool.com/git/
https://gitbook.tw/
https://blog.yorkxin.org/posts/git-rebase.html
https://www.atlassian.com/git/tutorials

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# Gitflow
參考資料：https://www.atlassian.com/git/tutorials/comparing-workflows/gitflow-workflow