# git game

## start game

>[root@localhost gitgame]# git clone https://github.com/hgarc014/git-game.git

```
Cloning into 'git-game'...
remote: Enumerating objects: 243, done.
remote: Total 243 (delta 0), reused 0 (delta 0), pack-reused 243
Receiving objects: 100% (243/243), 2.44 MiB | 419.00 KiB/s, done.
Resolving deltas: 100% (84/84), done.
```



## Level 1

**README.md**

```markdown
Welcome to the git-game!!
This is a terminal game designed to test your knowledge of git commands. Each level in the game is a task to perform on this repo. Once you perform that task, you will be given your next task. There are a total of ten levels, each one harder than last!

Let's get this journey started!!
Clone this repository by running:

$ git clone https://github.com/hgarc014/git-game.git
Don't know a lot about git??

Then you should check these files for assistance:

https://github.com/mikeizbicki/ucr-cs100/blob/2015winter/textbook/cheatsheets/git-cheatsheet.md

https://github.com/mikeizbicki/ucr-cs100/tree/2015winter/textbook/tools/git/advanced-git

Otherwise, you are free to continue...

You can win a badge for completing this game!

learn more about badges here: https://openbadgefactory.com/faq

You should always check the README.md file for your next clue!

Level 1

Your first task is to checkout the commit whose commit message is the answer to this question:

When a programmer is born, what is the first thing he/she learns to say?
```

**操作**

>[root@localhost git-game]# ls

```
LICENSE  README.md
```

>[root@localhost git-game]# vim README.md 
>[root@localhost git-game]# git log

```
commit d851edda3009332dd5d3f8f949a102f279dad809
Author: Henry Garcia <hgarc014@ucr.edu>
Date:   Wed Jun 10 21:03:04 2015 -0700

        updated README for badge notification

commit 7c8c3ccc2f4bb118a657f1f7a7ab4e163d1b7a30
Author: Henry Garcia <hgarc014@ucr.edu>
Date:   Wed Jun 10 20:57:08 2015 -0700

        added level1

commit 228389a54073ed1e6ec98e3bfa59039b416efd4d
Author: Henry Garcia <hgarc014@ucr.edu>
Date:   Wed Jun 10 20:56:34 2015 -0700

        added welcome screen

commit db99f2d9df4b2288d29a97d2d04a1703b4f3c107
Author: Henry Garcia <hgarc014@ucr.edu>
Date:   Wed Jun 10 20:55:35 2015 -0700

        updated README

commit 640273807f9bac8af03575f82b788663d4b99927
Author: Henry Garcia <hgarc014@ucr.edu>
Date:   Wed Jun 10 20:55:07 2015 -0700

        Hello World!

commit 8cafb7c87b129686da362b14c3f3c750c1fe4bf5
Author: Henry Garcia <hgarc014@ucr.edu>
```

>[root@localhost git-game]# git checkout 640273807f9bac8af03575f82b788663d4b99927

```
Note: checking out '640273807f9bac8af03575f82b788663d4b99927'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

 git checkout -b new_branch_name

HEAD is now at 6402738... Hello World!
```

## Level 2

**README.md**

```markdown
Hello World!

It looks like you have some knowledge about traversing commits!
Well, let's get this party started!
``Level 2``
We want to get to a branch whose name is the answer to this riddle:
I am a creature that is smaller than man, but many times more in number.
In code, my appearance can be subtle and no matter where I am found, I am unwanted.

What am I?
```

>[root@localhost git-game]# git branch -a

```
*(detached from 6402738) master remotes/origin/BillGates2014 remotes/origin/Daniel remotes/origin/HEAD -> origin/master remotes/origin/Henry remotes/origin/KenThompson2014 remotes/origin/Kevin remotes/origin/LinusTorvalds2014 remotes/origin/Mike remotes/origin/SteveJobs2014 remotes/origin/array remotes/origin/bug remotes/origin/code4life remotes/origin/keyboard remotes/origin/map remotes/origin/master remotes/origin/mouse remotes/origin/tree remotes/origin/trees remotes/origin/vector
```

**操作（导出分支）：**

>[root@localhost git-game]# git checkout bug



## Level 3

**README.md**

```markdown
git-game
========

Congratulations, it looks like you found the "bug."
When you work with other programmers on the same project, bugs are bound to appear.
One way to create bugs is by changing code that you did not write without understanding what the code is doing.

``Level 3``

Sometimes we like to blame others for introducing bugs in our code.
Think you can find out who introduced a bug into our file cool.cpp?
We think he had something to do with the development of git.
And from what we hear he also made a branch under his name.
Checkout to that branch after you find out who the culprit is.

If you are still confused, this link might [help](http://git-scm.com/docs/git-blame)
```

>[root@localhost git-game]# git log cool.cpp 

```
commit 3922a6d86ec4b0ea00c7b7414e96ffd3b2f65f45 Author: LinusTorvalds2014 <linustorvalds2014@gmail.com> Date:   Tue Dec 9 12:37:10 2014 -0800

       update

commit ce59bbfd5b04ece742e799c68bf94af2c46281d4 Author: Henry Garcia <hgarc014@ucr.edu> Date:   Mon Dec 8 18:22:35 2014 -0800

​     added cool.cpp and updated README
```

**操作**

>[root@localhost git-game]# git checkout LinusTorvalds2014

```
Branch LinusTorvalds2014 set up to track remote branch LinusTorvalds2014 from origin. Switched to a new branch 'LinusTorvalds2014'
```

## Level 4

**README.md**

```markdown
git-game
========

Looks like you found the branch of the evil Mastermind.
Things may start to get a little more challenging...

``Level 4``

The next clue you are looking for --
   is in a file you choose to ignore!

```

>[root@localhost git-game]# ls -a

```
.  ..  .git  .gitignore  LICENSE  README.md
```

>[root@localhost git-game]# vim .gitignore 

## Level 5

**.gitignore**

```shell
# welcome to the ignore file!!

#``Level 5``

# This file is hidden by default, 
# but did you know you have some branches that aren't shown to you,
# when you check the list of branches?
#
# For your next clue...
# Which abstract data type tends to implement sets and maps?? 
# The answer is the same answer to this riddle:
#
#   I am both mother and father.
#   I am seldom still
#   yet I never wander.
#   I never birth nor nurse.
#   
#   What am I?
#
# Afterwards... well, you
# know, checkout to the answer. 

*.rem
a.out

```

>[root@localhost git-game]# git checkout tree

```
Branch tree set up to track remote branch tree from origin. Switched to a new branch 'tree'
```

## Level 6

**README.md**

```markdown
git-game
========

``Level 6``

Welcome to the "tree" branch.
Looks like good ol' Linus modified the "nextclue_input.cpp" file.
Normally, when ran with the shell script "outputclue.sh", the "nextclue_input.cpp" file would give us the next hint.

Maybe, you should try running the shell script with the "nextclue_input.cpp" file and see what happens...

You can run the script by running the command "./outputclue.sh FILE" .
If you are on Windows, it's okey to use `git-bash` that is installed with [msysgit](https://msysgit.github.io/).

```

>[root@localhost git-game]# ls

```
LICENSE  nextclue_input.cpp  outputclue.sh  README.md
```

>[root@localhost git-game]# ./outputclue.sh nextclue_input.cpp 

```
Level 7:  Linus has been here... I love messing with these amateur programmers!! If you want some real fun, then you should try resolving a conflict between this branch (tree) and code4life. I introduced a little bug that you should fix in the conflict. >:) After you merge these 2 files you should run the shell script again!!

Good Luck!!!

Hint: https://help.github.com/articles/resolving-a-merge-conflict-from-the-command-line/
```

## Level 7

**output**

```
Level 7: 
Linus has been here...
I love messing with these amateur programmers!!
If you want some real fun, then you should try resolving a conflict between this branch (tree) and code4life.
I introduced a little bug that you should fix in the conflict. >:)
After you merge these 2 files you should run the shell script again!!

Good Luck!!!

 Hint: https://help.github.com/articles/resolving-a-merge-conflict-from-the-command-line/
```

> [root@localhost git-game]# git merge code4life

```
Auto-merging nextclue_input.cpp
CONFLICT (content): Merge conflict in nextclue_input.cpp
Automatic merge failed; fix conflicts and then commit the result.
```

>[root@localhost git-game]# vim nextclue_input.cpp 
>(delete line:)

```
<<<<<<< HEAD

    cout << "This file was useless, so I made it better..." << endl;
    while(1);
=======
```

>[root@localhost git-game]# ./outputclue.sh nextclue_input.cpp 

```
Well, congratulations!! You fixed my conflict!!
If you would like to continue, then you should checkout to the mouse branch!!
```

>[root@localhost git-game]# git reset --hard origin/tree
>[root@localhost git-game]# git checkout mouse

```
Branch mouse set up to track remote branch mouse from origin.
Switched to a new branch 'mouse'
```




## Level 8

**README.md**

``` markdown
git-game
========

``Level 8``

Looks like you resolved your conflict and found our branch, congrats!!

Hmm...it seems this branch has a file that was seen before in another branch.
Do you "remember" what it is?
I think this file has something to do with the next clue, but it seems to be very ugly looking.
Maybe if we compare the "diff"erences between this file and the file from before we'll know where to go next...
```

>[root@localhost git-game]# git diff bug..mouse remember

```
diff --git a/remember b/remember
index 584a931..76bd37c 100644
--- a/remember
+++ b/remember
@@ -2312,7 +2312,7 @@ C7EpVk1Cth5p2tKx0w58i ytUWbvyeysGWv jS4QWZkzlAN2m3EqLffpZiy1XM izQzulpiV Q5eNfJ7
 mrLDUvQK6M 2bREkk3RREZe6Ulawm3SU KHtoKj6jzKwhFYPzhcx1O4Culugp 0UzKqH9CjHM8akQ156fOYAeUUFp McAAI BHuGYzuoqoTSY 7Rby9YLfIMMcysFELGcL1rLD QAo0CaRo22ZfTaf2k iu9KM9ukJ67 EtoBFF9N2Dup5prFQ1 B51i0K
 5NKuMyGGyQum5oQkvP8Am08 OeNWMuTPJIpaBkK LupcmcIO4axxMfp8KnAo m7PFvaY9M5fAn9lfo7Bkm4PBvJJ01 ii2LvkHC8gJ EsHtRTZToBKe pA7ij1m1 bkgGGuQjorQhc0l3bkb7XUoJjII 5ul hxlFoWzySnS M nUlxc5wg2VNIz7lSuuC
 57EyTqwnFMX 3CmavTItFa9yjtSIjZ i1VTU06u9rj HShUtnwlqL7ZUZP0i8o7hq U0cS Cr9 sTRitmSvJ7pSDPdd5Emzh xKPGY7mUWTn972NHq HjtdwgQN45QNSZr fyYf 1kBsF5xzcRoyv5K08jlAfoc oG Byz6CAD G4rpwi7HbWlxa0tge m
-Sn In a branch named: Henry YtrydjKsYqebDoI3h bTINUeV6 pTVY8jnK2re HRwwNy25Ps6 u0YChCo5Jtw N3xkH3G nx aGo6yQTW RVZMsf3xk tBL0sG9GAR HQbyGYdqs i6dx1fyIPGJVciz8Z1NzdrvGE CKgkFauXqfKJmas cDLerW
+Sn The next clue is: YtrydjKsYqebDoI3h bTINUeV6 pTVY8jnK2re HRwwNy25Ps6 u0YChCo5Jtw N3xkH3G nx aGo6yQTW RVZMsf3xk tBL0sG9GAR HQbyGYdqs i6dx1fyIPGJVciz8Z1NzdrvGE CKgkFauXqfKJmas cDLerWvBTRzUi
 n9ec28c7rYYGTF W933ju5 pyH8PXHnKhlwLU0C2akSaPrlpprD spXXhVp6X A6dTg1fBfNBwSvp1sw91Dav67x8f8b Q DAUTWahNriDlArXunXMJ3b489 lcgvI2SViBLrCulZCwsi4kog 4rDVp 90SWto6WkU4Qj gANCojbKr1omMS3hm6p1csqH
 lDSkBLh Sy7L w4X8QJuiL yJ 9KjSn2C12NV 5E7H9S4M7LrV lgxJn1Q8xcnyprQ34g2tC7 Doc36AAsmi58xKa0 kRQntjBdrPfD0QLOj1m ChzWh7JLGBRU Xs446EYE71sHMjtbSsOW4LeVK hzcX391c0Kpyj5bL7sSI5NmE ZrBux2YhJypFB07
 lMrAVrH6 ZzHYozHGN f fE5ficRh2 pMQ6rpXtT49gijgjsO5eykZ9A o 30Tz1Agt5XgV 6odhdhHyYpV8U ZV qc3xnKKPYmjkeJwNGlAtXj f65vcbrsDI7od0E 50EVbGO7iT8Nk2Tilx52wRddM9HeA U8pEHg21Y5CfYjtI5Mnz GZ4lwoqno2Y
```

```
In a branch named: Henry
```

> [root@localhost git-game]# git checkout -b Henry origin/Henry

```
Branch Henry set up to track remote branch Henry from origin.
Switched to a new branch 'Henry'
```

## Level 9

## Level 10

**README.md**

```markdown
git-game
========

``Level 10``

Welcome!! It looks like you made it to my Branch!!!
Generally you want to refrain from making tags the same name as branches, unless you have a good reason.
The tag is more like the stable release.
While the branch is more like the in progress feature, which will be added soon.

You're almost done!! Excited?? Hope you are! You have one more thing to do!

Now its time to update the master branch, updating is really useful when you fork a repository and your forked repo starts to get behind on commits. The repository to update from is: https://github.com/drami025/git-game.git

Don't cheat!!

Here is a [link](https://help.github.com/articles/configuring-a-remote-for-a-fork/) that explains how to fork a remote repository.

```

>[root@localhost git-game]# git checkout master

```
Switched to branch 'master'
```

>[root@localhost git-game]# git remote add upstream ```

```
https://github.com/drami025/git-game.git
```

>[root@localhost git-game]# git fetch upstream

```
remote: Enumerating objects: 38, done.
Unpacking objects: 100% (38/38), done.
remote: Total 38 (delta 0), reused 0 (delta 0), pack-reused 38
From https://github.com/drami025/git-game
 * [new branch]      master     -> upstream/master
```

>[root@localhost git-game]# git merge upstream/master

```
Updating d851edd..de79125
Fast-forward
 README.md | 51 +++++++++++++++++++++++++--------------------------
 1 file changed, 25 insertions(+), 26 deletions(-)
```

**README.md**

``` markdown
Git Game Finish Line
==========

If you did not update the main git-game repository, then we are disappointed in you!!
=======

However, if you did, then great Job!!
You completed our Git Game!


Well you:

- viewed previous commits using "git log"
- traversed to previous commits
- checked out to different branches
- ran "git blame" to see who made changes to a file
- ran the diff command to see differences between branches
- saw what .gitignore included and how it works
- resolved merged conflicts
- saw issues with naming tags and branches the same name
- updated a local repository from a remote repository

 Version control systems like git are extremely important tools to learn and use,
 Especially when collaborating on projects with other developers.
 It is our hope that you continue to practice your git skills so that you can one day become the ultimate git master!

 Thanks for playing!

 email gitgame.hgarc014@gmail.com with subject: “git-game completion” to get a badge of completion!!
 please note you will not get a response from this email!

 **Please allow up to 2 weeks for the badge to be delivered!!**
 **I try to send badges as soon as possible, Thank You!!**
```

git game

[参考网址](https://www.liaoxuefeng.com/wiki/0013739516305929606dd18361248578c67b8067c8c017b000)

## 1.配置文件

### 1.1 配置命令

通常刚安装完git都会进行配置用户信息

>git config --global user.name "Your Name"
>
>git config --global user.email "email@example.com"

git 存在三份配置文件。



**linux**

```
system /etc/gitconfig
global ~/.gitconfig
local  .git/config
```

**window**

```
system D:/software/Git/mingw64/etc/gitconfig
global C:/Users/Administrator/.gitconfig 
local  .git/config
```

**三份配置分别对应到指令**
系统配置

> git config --system

用户配置

> git config --global

本地配置(指定仓库配置)

> git config  --local

**作用范围**
权重 local  > global > system

使用指令查看当前目录使用值

> git config user.name(key)

使用指令查看所有配置(相同key以最下方的为准)

> git config -l

### 1.2 例子

root用户执行以下命令配置文件

```
[root@localhost /]# mkdir data/test
[root@localhost /]# cd data/test/
[root@localhost test]# git init
Initialized empty Git repository in /data/test/.git/
[root@localhost test]# git config --local user.name 'localUser'
[root@localhost test]# git config --global user.name 'globalUser'
[root@localhost test]# git config --system user.name 'systemUser'
```

**测试1**

global 配置为每一个登陆用户单独一份

system 配置为系统配置(作用域最广)

local 为本地仓库配置(对应到一个项目仓库)

[root]

```
[root@localhost test]# git config --global user.name
globalUser
[root@localhost test]# git config --local user.name
localUser
[root@localhost test]# git config --global user.name
globalUser
[root@localhost test]# git config --system user.name
systemUser

```

[gituser]

```
[gituser@localhost test]$ git config --local user.name
localUser
[gituser@localhost test]$ git config --global user.name
[gituser@localhost test]$ git config --system user.name
systemUser
```

**测试2**

root 增加配置

```
[root@localhost test]# git config --global user.email '786725551@qq.com'
[root@localhost test]# git config --system user.email 'yui@test.com'
```

[root]

```
[root@localhost test]# git config user.email
786725551@qq.com
[root@localhost test]# git config user.name
localUser
```

*1.三份配置同时存在 user.name 取 local 配置*

*2.global 和 system 配置同时存在 user.email ，local 不存在，去global*

权重 local > global > system

**测试3**

>git config -l

[root]

```
[root@localhost test]# git config -l
user.name=systemUser
user.email=yui@test.com
user.name=globalUser
user.email=786725551@qq.com
core.repositoryformatversion=0
core.filemode=true
core.bare=false
core.logallrefupdates=true
user.name=localUser
```

## 2.快速入门

### 2.1 创建版本库

```
[root@localhost data]# mkdir my_repository
[root@localhost data]# cd my_repository/
[root@localhost my_repository]# git init
Initialized empty Git repository in /data/my_repository/.git/
```

### 2.2 提交文件

**1.添加文件，命令将文件内容添加到索引(将修改添加到暂存区)。也就是将要提交的文件的信息添加到索引库**

>git add fileName

**2.提交文件**

>git commit -m '提交日志信息'

**说明：add 可以多次使用。之后 commit 把 add 的文件一次性提交到仓库中**

### 2.3 修改文件

对文件进行修改后

**1.查看当前仓库信息**

>git status

```
# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#	modified:   readme.md
#
# Changes not staged for commit:
#   (use "git add <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#
#	modified:   readme.md
#
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#	testFile.md
```

在 master 分支中， add 没 commit (带提交)， 修改没 add 没 commit， 新增没 add 没 commit

2.查看文件修改内容

> git diff

```
diff --git a/readme.md b/readme.md
index b5d1636..8fe7fa9 100644
--- a/readme.md
+++ b/readme.md
@@ -1,3 +1,4 @@
 # this is my test of git
 # this is the second commit
 # add
+# test diff
diff --git a/testFile.md b/testFile.md
index 0bf9a0f..55ed874 100644
--- a/testFile.md
+++ b/testFile.md
@@ -1 +1,2 @@
 # the test file 2
+# test diff

```

### 2.4 提交记录

git log命令显示从最近到最远的提交日志

>git log

```
commit 5888679a615f5f2d2387b1edd35718f44f0a9814
Author: globalUser <786725551@qq.com>
Date:   Wed Jan 23 00:51:56 2019 -0500

    commit 4

commit a80f4aeca6efffa0ab36f6f403453b1a1e83107c
Author: globalUser <786725551@qq.com>
Date:   Tue Jan 22 22:51:13 2019 -0500

    add testFile.md update readme.md third[C

commit 1566217be62b7e69146a0e5cadeca86e3ecdf019
Author: globalUser <786725551@qq.com>
Date:   Tue Jan 22 22:48:13 2019 -0500

    second commit

commit a2d84e1c4c818b0a2babed82bdcd2c581c506a8f
Author: globalUser <786725551@qq.com>
Date:   Tue Jan 22 22:38:52 2019 -0500

    add readme.md
```

隐藏详细信息

>git log --pretty=oneline

```
[root@localhost my_repository]# git log --pretty=oneline
5888679a615f5f2d2387b1edd35718f44f0a9814 commit 4
a80f4aeca6efffa0ab36f6f403453b1a1e83107c add testFile.md update readme.md third[C
1566217be62b7e69146a0e5cadeca86e3ecdf019 second commit
a2d84e1c4c818b0a2babed82bdcd2c581c506a8f add readme.md
```

类似 5888679a615f5f2d2387b1edd35718f44f0a9814 是版本号 id

查看被回滚（见 2.5）的版本

>git reflog

```
[root@localhost my_repository]# git log --pretty=oneline
1566217be62b7e69146a0e5cadeca86e3ecdf019 second commit
a2d84e1c4c818b0a2babed82bdcd2c581c506a8f add readme.md
[root@localhost my_repository]# git reflog
1566217 HEAD@{0}: reset: moving to HEAD^^
5888679 HEAD@{1}: commit: commit 4
a80f4ae HEAD@{2}: commit: add testFile.md update readme.md third[C
1566217 HEAD@{3}: commit: second commit
a2d84e1 HEAD@{4}: commit (initial): add readme.md

```

**log 路线图**

>git log --graph --pretty=oneline --abbrev-commit
>
>**由于 git 是分布式的版本控制系统所有，它使用的版本号id不限svn一样是一个递增的数字，而是一个 SHA1 计算出来的一个非常大的数字，用十六进制表示**

### 2.5 版本回退

>git reset --hard HEAD^^

```
[root@localhost my_repository]# git log --pretty=oneline
5888679a615f5f2d2387b1edd35718f44f0a9814 commit 4
a80f4aeca6efffa0ab36f6f403453b1a1e83107c add testFile.md update readme.md third[C
1566217be62b7e69146a0e5cadeca86e3ecdf019 second commit
a2d84e1c4c818b0a2babed82bdcd2c581c506a8f add readme.md
[root@localhost my_repository]# git reset --hard HEAD^^
HEAD is now at 1566217 second commit
[root@localhost my_repository]# git log --pretty=oneline
1566217be62b7e69146a0e5cadeca86e3ecdf019 second commit
a2d84e1c4c818b0a2babed82bdcd2c581c506a8f add readme.md
```

**git reset --hard 版本号**

[--soft | --mixed | --hard | --merge | --keep] 此处暂且不讲

版本号可以只写前几位，唯一即可；

HEAD 为当前版本  

HEAD^ 为上一个版本，多少个^多少个版本前

HEAD~100 表示 100 个^

### 2.6 名词解释

**工作区（Working Directory）**：仓库目录

**版本库（Repository）**：工作区中的 .git 目录

**暂存区（stage）**：在.git 文件夹里面还有很多文件，其中有一个index 文件 就是暂存区也可以叫做 stage ,git还为我们自动生成了一个分支master以及指向该分支的指针head

git add 是将文件添加到 stage 中， 而 git commit 这是将暂存区的文件提交到仓库中
已经修改的文件如果没有添加到暂存区中，是不会被 git commit 提交上去的

### 2.7 撤销修改

**add 之前**

>git checkout -- file

git checkout 其实是用版本库里的版本替换工作区的版本

**commit 之前，add 之后**

>git reset HEAD

### 2.8 文件删除

>git rm file

```
[root@localhost my_repository]# git rm test.md 
rm 'test.md'
[root@localhost my_repository]# ls
readme.md
[root@localhost my_repository]# git commit -m "del test.md"
[master b67629b] del test.md
 1 file changed, 0 insertions(+), 0 deletions(-)
 delete mode 100644 test.md
```

## 3. 远程仓库

### 3.1 推送远程仓库

先在 github 创建一个仓库

**本地关联到远程仓库**

>git remote add origin https://github.com/XuZhuohao/my_repository.git

**推送至远程仓库**

>git push -u origin master

```
[root@localhost my_repository]# git remote add origin https://github.com/XuZhuohao/my_repository.git
[root@localhost my_repository]# git push -u origin master
Username for 'https://github.com': xuzhuohao^H^H
Password for 'https://xuzhuoh@github.com': 
[root@localhost my_repository]# git push -u origin master
Username for 'https://github.com': 786725551@qq.com
Password for 'https://786725551@qq.com@github.com': 
Counting objects: 20, done.
Compressing objects: 100% (13/13), done.
Writing objects: 100% (20/20), 1.58 KiB | 0 bytes/s, done.
Total 20 (delta 3), reused 0 (delta 0)
remote: Resolving deltas: 100% (3/3), done.
To https://github.com/XuZhuohao/my_repository.git
 * [new branch]      master -> master
Branch master set up to track remote branch master from origin.
```

**克隆远程仓库**

>git clone git@github.com:XuZhuohao/my_repository.git

```
[root@localhost data]# mkdir my_repository02
[root@localhost data]# cd my_repository02
[root@localhost my_repository02]# ls
[root@localhost my_repository02]# git clone git@github.com:XuZhuohao/my_repository.git
Cloning into 'my_repository'...
Warning: Permanently added the RSA host key for IP address '13.229.188.59' to the list of known hosts.
remote: Enumerating objects: 20, done.
remote: Counting objects: 100% (20/20), done.
remote: Compressing objects: 100% (10/10), done.
Receiving objects: 100% (20/20), done.
Resolving deltas: 100% (3/3), done.
remote: Total 20 (delta 3), reused 20 (delta 3), pack-reused 0

```

### 3.2 协议

#### 3.2.1 介绍

GitHub给出的地址不止一个。实际上，Git支持多种协议，默认的 git:// 使用ssh，但也可以使用https等其他协议。

使用https除了速度慢以外，还有个最大的麻烦是每次推送都必须输入口令，但是在某些只开放http端口的公司内部就无法使用ssh协议而只能用https

#### 3.2.2 ssh

**1.创建SSH Key**

>ssh-keygen -t rsa -C "youremail@example.com"

可以在用户主目录里找到.ssh目录，里面有id_rsa和id_rsa.pub两个文件，这两个就是SSH Key的秘钥对，id_rsa是私钥，不能泄露出去，id_rsa.pub是公钥，可以放心地告诉任何人

**2.github 生成 SSH Key**

github 个人页面 -> 右上角 Settings -> SSH and GPG keys -> SSH keys -> key 输入框中输入 id_rsa.pub 的数据 -> add SSH key

**3.由 http 切换到 ssh**
取消连接

>git remote remove origin 

连接到远程

>git remote add origin git@xxxxx

```
[root@localhost my_repository]# git remote remove origin
[root@localhost my_repository]# git remote add origin git@github.com:XuZhuohao/my_repository.git

```

## 4. 分支管理

### 4.1 创建与合并分支

**创建分支**

>git branch dev

**切换分支**

>git checkout dev

**创建并切换分支**

>git checkout -b devTest
>
>分支存在是会有异常
>
>-B 这表示强制创建，存在分支会被重建

```
[root@localhost my_repository]# git branch dev
[root@localhost my_repository]# git checkout dev
Switched to branch 'dev'
[root@localhost my_repository]# git checkout devTest
error: pathspec 'devTest' did not match any file(s) known to git.
[root@localhost my_repository]# git checkout -b devTest
Switched to a new branch 'devTest'
[root@localhost my_repository]# git checkout dev
Switched to and reset branch 'dev'
[root@localhost my_repository]# git checkout -b devTest
fatal: A branch named 'devTest' already exists.
[root@localhost my_repository]# git checkout -B devTest
Switched to and reset branch 'devTest'
```

**显示分支列表**

>git branch

```
[root@localhost my_repository]# git branch
    dev
* devTest
    master
```

git branch命令会列出所有分支，当前分支前面会标一个* 号

**分支合并**

>git merge branchName

将 branchName  合并到当前分支

```
[root@localhost my_repository]# git checkout master
Switched to branch 'master'
[root@localhost my_repository]# git merge dev
Updating fecde0f..af83606
Fast-forward
 readme.md | 1 +
 1 file changed, 1 insertion(+)
```

**删除**
删除分支

>git branch -d name

```
[root@localhost my_repository]# git branch -d devTest
Deleted branch devTest (was fecde0f).
[root@localhost my_repository]# git branch
    dev
* master
```

强行删除

>git branch -D name

**存在冲突**
自动合并失败;修复冲突，然后提交结果

```
[root@localhost my_repository]# git merge dev
Auto-merging readme.md
CONFLICT (content): Merge conflict in readme.md
Automatic merge failed; fix conflicts and then commit the result.
[root@localhost my_repository]# git status
# On branch master
# You have unmerged paths.
#   (fix conflicts and run "git commit")
#
# Unmerged paths:
#   (use "git add <file>..." to mark resolution)
#
#	both modified:      readme.md
#
no changes added to commit (use "git add" and/or "git commit -a")
[root@localhost my_repository]# vim readme.md 
[root@localhost my_repository]# git add readme.md 
[root@localhost my_repository]# git commit -m "update"
[master eae1d5c] update
[root@localhost my_repository]# git log --graph--pretty=oneline --abbrev-commit
fatal: unrecognized argument: --graph--pretty=oneline
[root@localhost my_repository]# git log --graph --pretty=oneline --abbrev-commit
*   eae1d5c update
|\  
| * 59408a7 k
* | 60e17ad tes
|/  
* af83606 update readme.md
...

```

### 4.3 分支管理策略

通常，合并分支时，如果可能，Git会用Fast forward模式，但这种模式下，删除分支后，会丢掉分支信息。

如果要强制禁用Fast forward模式，Git就会在merge时生成一个新的commit，这样，从分支历史上就可以看出分支信息

>git merge --no-ff -m "merge with no-ff" dev

```
[root@localhost my_repository]# git merge --no-ff -m "merge with no-ff" dev
Merge made by the 'recursive' strategy.
 readme.md | 1 +
 1 file changed, 1 insertion(+)

```

### 4.4 变更存储 stash

保存当前更改( commit 之前)

>git stash 

显示保存的版本

>git stash list

恢复到某个状态

>git stash apply stash@{0}

删除某个状态

>git stash drop stash@{0}

恢复并删除状态

>git stash pop


apply 和 drop 如果不声明状态标识，默认 stash@{0}
stash@{0} 标识最新保存的数据
其实由 pop 指令可以大概猜测 git 使用堆栈一样的结构来进行 stash， 先进的在下面。

### 4.5 分支命名说明

**master:** 主分支，主要用来版本发布。

**develop：**日常开发分支，该分支正常保存了开发的最新代码。

**feature：**具体的功能开发分支，只与 develop 分支交互。

**release：**release 分支可以认为是 master 分支的未测试版。比如说某一期的功能全部开发完成，那么就将 develop 分支合并到 release 分支，测试没有问题并且到了发布日期就合并到 master 分支，进行发布。

**hotfix：**线上 bug 修复分支,必须合并到 master 和 develop

### 4.6 远程分支

**查看远程分支**

>git branch -a

**checkout 远程分支**

>git checkout -b dev origin/dev
>git pull

**建立本地分支和远程分支的关联**

>git branch --set-upstream branch-name origin/branch-name

**本地创建和远程分支对应的分支**

>git checkout -b branch-name origin/branch-name

本地和远程分支的名称最好一致

### 4.7 rebase

git pull相当于是git fetch + git merge

1. 可以看出merge结果能够体现出时间线，但是rebase会打乱时间线。 
2. 而rebase看起来简洁，但是merge看起来不太简洁。 
3. 最终结果是都把代码合起来了，所以具体怎么使用这两个命令看项目需要。

## 5. tag 标签管理

**创建一个标签**

>git tag v1.0

默认最新提交的

**指定id创建一个标签**

>git tag v1.0 f52c633

**添加说明创建**

>git tag -a v0.1 -m "version 0.1 released" 1094adb

**显示所有 tag**

>git tag 

**显示详细信息**

>git show tagName

**删除标签**

>git tag -d v1.0

**push 到远程**

>git push origin v1.1

**删除远程标签**
1.删除本地

>git tag -d v1.1

2.推送删除

>git push origin :refs/tags/v1.1

## 6. 自定义 git

### 6.1 忽略文件

忽略某些文件时，需要编写.gitignore；

.gitignore文件本身要放到版本库里，并且可以对.gitignore做版本管理！

### 6.2 修改别名

**使用 st 代替 status**

>git config --global alias.st status

当然还有别的命令可以简写，很多人都用co表示checkout，ci表示commit，br表示branch：

git remote add upstream https://github.com/drami025/git-game.git

git 完全使用指南

# kafka quick start

**说明：** 使用版本 kafka_2.12-2.0.0

## 1. 安装

### 1.1 下载解压

>[root@localhost kafka]# wget https://mirrors.cnnic.cn/apache/kafka/2.0.0/kafka_2.12-2.0.0.tgz
>[root@localhost kafka]# tar -zxvf kafka_2.12-2.0.0.tgz
>[root@localhost kafka]# mv kafka_2.12-2.0.0 /usr/
>[root@localhost kafka]# mv kafka_2.12-2.0.0/ kafka



## 2. zookeeper

### 2.1 zookeeper.properties  

#### 2.1.1 配置修改

>[root@localhost kafka]# vim config/zookeeper.properties  

```
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
# 
#    http://www.apache.org/licenses/LICENSE-2.0
# 
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# the directory where the snapshot is stored.
dataDir=/usr/kafka/tmp/zookeeper
dataLogDir=/usr/kafka/tmp/log/zookeeper
# the port at which the clients will connect
clientPort=2181
# disable the per-ip limit on the number of connections since this is a non-production config
maxClientCnxns=100
tickTime=2000
initLimit=10
syncLimit=5

server.1=kafka01:2888:3888
server.2=kafka02:2888:3888
server.3=kafka03:2888:3888

quorumListenOnAllIPs=true

```

#### 2.1.2 quorumListenOnAllIPs 说明

异常：
```java.net.ConnectException: 拒绝连接 (Connection refused)```

>[root@localhost kafka]# netstat -nalp|grep java  

显示未监听2888，3888端口

[参考文章](https://blog.csdn.net/u014284000/article/details/74508963) *存疑*

#### 2.1.3 其他

**dataLogDir：** 日志接受，需要手动，不会自动生成

#### 2.1.4 配置说明

zookeeper.properties 所有机子的配置都一样

### 2.2 myid

根据 zookeeper.properties 配置中的 dataDir 创建文件myid，在myid中输入当前server的id，
server.1的输入1，与zookeeper.properties一致，每个服务器不一样

>[root@localhost kafka]# vim /usr/kafka/tmp/zookeeper/myid

### 2.3 hosts

>[root@localhost kafka]# vim /etc/hosts

```
10.1.161.182 kafka01
10.1.161.182 kafka02
10.1.161.183 kafka03
```

## 3. kafka

### 3.1 server.properties 

#### 3.1.1 配置修改

>[root@localhost kafka]# vim config/server.properties 

```
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# see kafka.server.KafkaConfig for additional details and defaults

############################# Server Basics #############################

# The id of the broker. This must be set to a unique integer for each broker.
broker.id=0

############################# Socket Server Settings #############################

# The address the socket server listens on. It will get the value returned from 
# java.net.InetAddress.getCanonicalHostName() if not configured.
#   FORMAT:
#     listeners = listener_name://host_name:port
#   EXAMPLE:
#     listeners = PLAINTEXT://your.host.name:9092
#listeners=PLAINTEXT://:9092
host.name=10.1.161.181
# Hostname and port the broker will advertise to producers and consumers. If not set, 
# it uses the value for "listeners" if configured.  Otherwise, it will use the value
# returned from java.net.InetAddress.getCanonicalHostName().
#advertised.listeners=PLAINTEXT://your.host.name:9092

# Maps listener names to security protocols, the default is for them to be the same. See the config documentation for more details
#listener.security.protocol.map=PLAINTEXT:PLAINTEXT,SSL:SSL,SASL_PLAINTEXT:SASL_PLAINTEXT,SASL_SSL:SASL_SSL

# The number of threads that the server uses for receiving requests from the network and sending responses to the network
num.network.threads=3

# The number of threads that the server uses for processing requests, which may include disk I/O
num.io.threads=8

# The send buffer (SO_SNDBUF) used by the socket server
socket.send.buffer.bytes=102400

# The receive buffer (SO_RCVBUF) used by the socket server
socket.receive.buffer.bytes=102400

# The maximum size of a request that the socket server will accept (protection against OOM)
socket.request.max.bytes=104857600


############################# Log Basics #############################

# A comma separated list of directories under which to store log files
log.dirs=/usr/kafka/tmp/log/kafka

# The default number of log partitions per topic. More partitions allow greater
# parallelism for consumption, but this will also result in more files across
# the brokers.
num.partitions=1

# The number of threads per data directory to be used for log recovery at startup and flushing at shutdown.
# This value is recommended to be increased for installations with data dirs located in RAID array.
num.recovery.threads.per.data.dir=1

############################# Internal Topic Settings  #############################
# The replication factor for the group metadata internal topics "__consumer_offsets" and "__transaction_state"
# For anything other than development testing, a value greater than 1 is recommended for to ensure availability such as 3.
offsets.topic.replication.factor=1
transaction.state.log.replication.factor=1
transaction.state.log.min.isr=1

############################# Log Flush Policy #############################

# Messages are immediately written to the filesystem but by default we only fsync() to sync
# the OS cache lazily. The following configurations control the flush of data to disk.
# There are a few important trade-offs here:
#    1. Durability: Unflushed data may be lost if you are not using replication.
#    2. Latency: Very large flush intervals may lead to latency spikes when the flush does occur as there will be a lot of data to flush.
#    3. Throughput: The flush is generally the most expensive operation, and a small flush interval may lead to excessive seeks.
# The settings below allow one to configure the flush policy to flush data after a period of time or
# every N messages (or both). This can be done globally and overridden on a per-topic basis.

# The number of messages to accept before forcing a flush of data to disk
#log.flush.interval.messages=10000

# The maximum amount of time a message can sit in a log before we force a flush
#log.flush.interval.ms=1000

############################# Log Retention Policy #############################

# The following configurations control the disposal of log segments. The policy can
# be set to delete segments after a period of time, or after a given size has accumulated.
# A segment will be deleted whenever *either* of these criteria are met. Deletion always happens
# from the end of the log.

# The minimum age of a log file to be eligible for deletion due to age
log.retention.hours=168

# A size-based retention policy for logs. Segments are pruned from the log unless the remaining
# segments drop below log.retention.bytes. Functions independently of log.retention.hours.
#log.retention.bytes=1073741824

# The maximum size of a log segment file. When this size is reached a new log segment will be created.
log.segment.bytes=1073741824

# The interval at which log segments are checked to see if they can be deleted according
# to the retention policies
log.retention.check.interval.ms=300000

############################# Zookeeper #############################

# Zookeeper connection string (see zookeeper docs for details).
# This is a comma separated host:port pairs, each corresponding to a zk
# server. e.g. "127.0.0.1:3000,127.0.0.1:3001,127.0.0.1:3002".
# You can also append an optional chroot string to the urls to specify the
# root directory for all kafka znodes.
zookeeper.connect=kafka01:2181,kafka02:2181,kafka03:2181

# Timeout in ms for connecting to zookeeper
zookeeper.connection.timeout.ms=6000


############################# Group Coordinator Settings #############################

# The following configuration specifies the time, in milliseconds, that the GroupCoordinator will delay the initial consumer rebalance.
# The rebalance will be further delayed by the value of group.initial.rebalance.delay.ms as new members join the group, up to a maximum of max.poll.interval.ms.
# The default value for this is 3 seconds.
# We override this to 0 here as it makes for a better out-of-the-box experience for development and testing.
# However, in production environments the default value of 3 seconds is more suitable as this will help to avoid unnecessary, and potentially expensive, rebalances during application startup.
group.initial.rebalance.delay.ms=0

```

#### 3.1.2 broker.id

 broker.id 每个服务器唯一，不能一一
 ``` broker.id=0 ```

 #### 3.1.3 log.dirs

 log.dirs 对应日志地址，需要手动创建

 ```log.dirs=/usr/kafka/tmp/log/kafka```

 #### 3.1.4  zookeeper.connect

  zookeeper.connect 连接zookeeper
  ``` zookeeper.connect=kafka01:2181,kafka02:2181,kafka03:2181 ```

## 4. 启动

### 4.1 启动zookeeper

>[root@localhost kafka]# /bin/zookeeper-server-start.sh config/zookeeper.properties &

### 4.2 启动kafka

> ./bin/kafka-server-start.sh config/server.properties &

kafka: 环境搭建

## DFS 和 HDFS 

### DFS (Distributed file system)

1.分布式文件系统讨论管理数据，即跨多台计算机或服务器的文件或文件夹。换句话说，DFS是一种文件系统，允许我们将数据存储在群集中的多个节点或机器上，并允许多个用户访问数据。所以基本上，它与您的机器中可用的文件系统具有相同的用途。  

2.DFS为文件系统提供了单个访问点和一个逻辑树结构，通过DFS，用户在访问文件时不需要知道它们的实际物理位置，即分布在多个服务器上的文件在用户面前就如同在网络的同一个位置。  



### HDFS Hadoop Distributed File System)

1.HDFS (Hadoop Distributed File System)是Hadoop的核心子项目，是一个可以运行在普通硬件设备上的分布式文件系统，是分布式计算中数据存储和管理的基础，是基于流  数据模式访问和处理超大文件的需求而开发的。它所具有的高容错、高可靠性、高可扩展性、高吞吐率等特征为海量数据提供了不怕故障的存储，给超大数据集（Large Data  Set） 的应用处理带来了很多便利。  
2.HDFS 设计目标  
· 硬件故障是常态，而不是异常  
· 适合流式数据访问  
· 适合大规模数据集  
· 简单的一致性模型  
· 移动计算比移动数据更划算  
· 轻便的访问异构的软硬件平台  
2.1.流式数据、批式数据、实时数据、历史数据的区别  

```
大数据处理系统可分为批式(batch)大数据和流式(streaming)大数据两类。其中，批式大数据又被称为历史大数据，流式大数据又被称为实时大数据。
复杂的批量数据处理（batch data processing），通常的时间跨度在数十分钟到数小时之间。
基于历史数据的交互式查询（interactive query），通常的时间跨度在数十秒到数分钟之间。
基于实时数据流的数据处理（streaming data processing），通常的时间跨度在数百毫秒到数秒之间。
```

2.2.一致性模型  

```
以下面的例子说：
一行X值在节点M和节点N上有副本
客户端A在节点M上写入行X的值
一段时间后，客户端B在节点N上读取行X的值
一致性模型所要做的就是决定客户端B能否看到客户端A写的值

常用的一致性模型：
1、最终一致性（eventual consistency）
最终一致性有个重大缺点：在系统达到副本收敛之前，系统有可能返回任何值
2、强一致性模型（strong consistency）
所有并行的进程（节点，处理器等）看到的是一样的存取顺序
也就是只有一种状态被所有的并行进程观察到，对比与弱一致性（weak consitency），并行进程可能看到不同的状态。
```

2.3.移动计算,移动数据

```
移动数据：业务逻辑处理数据时，把数据移动到逻辑计算节点进行计算
移动计算：业务逻辑处理数据时，把计算程序移动到需要计算的数据节点进行计算
```

## HDFS的架构和数据存储原理

### Client：就是客户端。  

1、文件切分。文件上传 HDFS 的时候，Client 将文件切分成一个一个的Block，然后进行存储。  
2、与 NameNode 交互，获取文件的位置信息。  
3、与 DataNode 交互，读取或者写入数据。  
4、Client 提供一些命令来管理 HDFS，比如启动或者关闭HDFS。  
5、Client 可以通过一些命令来访问 HDFS。  

### NameNode：就是 master，它是一个主管、管理者。  

1、管理 HDFS 的名称空间。  
2、管理数据块（Block）映射信息  
3、配置副本策略  
4、处理客户端读写请求。  

### DataNode：就是Slave。NameNode 下达命令，DataNode 执行实际的操作。  

1、存储实际的数据块。  
2、执行数据块的读/写操作。  

### Secondary NameNode：并非 NameNode 的热备。当NameNode 挂掉的时候，它并不能马上替换 NameNode 并提供服务。  

1、辅助 NameNode，分担其工作量。  
2、定期合并 fsimage和fsedits，并推送给NameNode。  
3、在紧急情况下，可辅助恢复 NameNode。

## 文件上传举例

### Client向HDFS上传一个200M大小的日志文件的大致过程

首先，Client发起文件上传请求，即通过RPC与NameNode建立通讯。  
NameNode与各DataNode使用心跳机制来获取DataNode信息。NameNode收到Client请求后，获取DataNode信息，并将可存储文件的节点信息返回给Client。  
Client收到NameNode返回的信息，与对应的DataNode节点取得联系，并向该节点写文件。  
文件写入到DataNode后，以流水线的方式复制到其他DataNode（当然，这里面也有DataNode向NameNode申请block，这里不详细介绍），至于复制多少份，与所配置的hdfs-default.xml中的dfs.replication相关。  


## 为什么选择 HDFS 存储数据？

### 优点：  

**(1) 高容错性**

1) 数据自动保存多个副本。它通过增加副本的形式，提高容错性。  
2) 某一个副本丢失以后，它可以自动恢复，这是由 HDFS 内部机制实现的，我们不必关心。  

**(2) 适合批处理**
   
3) 它是通过移动计算而不是移动数据。  
4) 它会把数据位置暴露给计算框架。

 
**(3) 适合大数据处理**
  
5) 数据规模：能够处理数据规模达到 GB、TB、甚至PB级别的数据。  
6) 文件规模：能够处理百万规模以上的文件数量，数量相当之大。  
7) 节点规模：能够处理10K节点的规模。  


**(4) 流式数据访问**  
   
8) 一次写入，多次读取，不能修改，只能追加。  
9) 它能保证数据的一致性。  


 **(5) 可构建在廉价机器上** 
  
10) 它通过多副本机制，提高可靠性。  
11) 它提供了容错和恢复机制。比如某一个副本丢失，可以通过其它副本来恢复。  

### 劣势：  

**不适合低延时数据访问**

1) 比如毫秒级的来存储数据，这是不行的，它做不到。  
2) 它适合高吞吐率的场景，就是在某一时间内写入大量的数据。但是它在低延时的情况  下是不行的，比如毫秒级以内读取数据，这样它是很难做到的。   

**无法高效的对大量小文件进行存储**

3) 存储大量小文件的话，它会占用  NameNode大量的内存来存储文件、目录和块信息。这样是不可取的，因为NameNode的内存总是有限的。  
4) 小文件存储的寻道时间会超过读取时间，它违反了HDFS的设计目标。 改进策略  

**无法并发写入、文件随机修改**

5) 一个文件只能有一个写，不允许多个线程同时写。  
6) 仅支持数据 append（追加），不支持文件的随机修改。  

## HDFS 如何读取文件？ 

1. 首先调用FileSystem对象的open方法，其实获取的是一个DistributedFileSystem的实例。  
2. DistributedFileSystem通过RPC(远程过程调用)获得文件的第一批block的locations，同一block按照重复数会返回多个locations，这些locations按照hadoop拓扑结构排序，距离客户端近的排在前面。  
3. 前两步会返回一个FSDataInputStream对象，该对象会被封装成 DFSInputStream 对象，DFSInputStream可以方便的管理datanode和namenode数据流。客户端调用read方 法，DFSInputStream就会找出离客户端最近的datanode并连接datanode。  
4. 数据从datanode源源不断的流向客户端。  
5. 如果第一个block块的数据读完了，就会关闭指向第一个block块的datanode连接，接着读取下一个block块。这些操作对客户端来说是透明的，从客户端的角度来看只是    读一个持续不断的流。  
6. 如果第一批block都读完了，DFSInputStream就会去namenode拿下一批blocks的location，然后继续读，如果所有的block块都读完，这时就会关闭掉所有的流。  


## HDFS 如何写入文件？ 

1. 客户端通过调用 DistributedFileSystem 的create方法，创建一个新的文件。  
2. DistributedFileSystem  通过  RPC（远程过程调用）调用   NameNode，去创建一个没有blocks关联的新文件。创建前，NameNode  会做各种校验，比如文件是否存在， 客户端有无权限去创建等。如果校验通过，NameNode 就会记录下新文件，否则就会抛出IO异常。  
3. 前两步结束后会返回 FSDataOutputStream 的对象，和读文件的时候相似，FSDataOutputStream 被封装成 DFSOutputStream，DFSOutputStream 可以协调NameNode和 DataNode。客户端开始写数据到DFSOutputStream,DFSOutputStream会把数据切成一个个小packet，然后排成队列data queue。  
4. DataStreamer 会去处理接受 data queue，它先问询 NameNode 这个新的 block 最适合存储的在哪几个DataNode里，比如重复数是3，那么就找到3个最适合的DataNode，把它们排成一个 pipeline。DataStreamer 把 packet 按队列输出到管道的第一个 DataNode 中，第一个 DataNode又把 packet 输出到第二个 DataNode 中，以此类推。  
5. DFSOutputStream 还有一个队列叫 ack queue，也是由 packet 组成，等待DataNode的收到响应，当pipeline中的所有DataNode都表示已经收到的时候，这时akc queue才会把对应的packet包移除掉。  
6. 客户端完成写数据后，调用close方法关闭写入流。  
7. DataStreamer 把剩余的包都刷到 pipeline 里，然后等待 ack 信息，收到最后一个ack 后，通知 DataNode 把文件标示为已完成  

## HDFS 副本存放策略

namenode 如何选择在哪个 datanode 存储副本（replication）？这里需要对可靠性、写入带宽和读取带宽进行权衡。 Hadoop 对 datanode 存储副本有自己的副本策略，在其发展过程中一共有两个版本的副本策略，分别如下所示。  

### 1.Hadoop 0.17之前的副本策略  

第一个副本：存储在同机架的不同节点上。  
第二个副本：存储在同机架的另外一个节点上。  
第三个副本：存储在不同机架的另外一个节点。其它副本：选择随机存储。  

### 2.Hadoop 0.17 之后的副本策略  

第一个副本：存储在同 Client 相同节点上。  
第二个副本：存储在不同机架的节点上。  
第三个副本：存储在第二个副本机架中的另外一个节点上。其它副本：选择随机存储。

HDFS 初探

## css引入css基础选择器选择器权重  

### 1.CSS:cascading style sheet 层叠样式表格

### 2.引入：  

```
<html>
<head>
	<title></title>
	
	<style type="text/css"> 
		div{
			width:100px;
			height:100px;
			background-color: red;
		}

	</style>
	
	<link rel="stylesheet" type="text/css" href="url">
</head>
<body>
	
	<div style="width:100px;height:100px;background-color: red;"></div>
</body>
</html>
```



### 3.选择器  

```
<!DOCTYPE html>
<html>
<head>
	<title></title>
	<style type="text/css">
		/*
		1.id选择器:一个元素只能有一个id值，一个id值对应一个元素
		*/
		#only {
			width: 100px;
		}
		/*
		2.class选择：一个元素可以有多个class一个class可以对应多个元素
		*/
		.demo {
			width: 100px;
		}
		.demo1 {
			background-color: red;
		}
		/*
		3.标签选择器
		*/
		div {
			height: 100px;
		}
		/*4.通配符:所有标签*/
		* {
			padding: 0px;
		}
		/*
		5.属性选择器  
		   选出所有有属性id的标签
		*/
		[id] {
			
		}
		/*所有有属性id且值为value的标签*/
		[id="value"]{
	
		}
	</style>
</head>
<body>
	<div id="only" class="demo">123</div>
	<div class="demo" class="demo2">123</div>
</body>
</html>
```

### 4.样式优先级  

行间样式 > ID选择器 > class选择器(属性选择器) > 标签选择器 > 通配符  

同权重看顺序，后面覆盖前面

**!important最大**
**css权重：(256进制)**  

```
!important                 Infinity
行间样式                   1000
ID                         100  
class|属性|伪类            10  
标签|伪元素                1  
通配符                     0  
```


## css复杂选择器，权重计算问题，css基础属性  

### 1.复杂选择器  

```
<!DOCTYPE html>
<html>
<head>
	<title></title>
	<style type="text/css">
		/*1.父子选择器/派生选择器：
			每一个层级不一定是标签
			不一定是父子，可以跨层级
		*/
		/*选择div里面所有span*/
		div span{
			background-color: red;
		}
		/*2.直接父子元素选择器
		*/
		/*只选择内容01*/
		div > em{

		}
		/*3.并列选择器：多个限制条件不加空格组合到一起*/
		/*选中2*/
		div.demo{

		}

	</style>
</head>
<body>
	
	<div>
		<span>内容</span>
		<em>内容01</em>
		<strong>
			<em>内容02</em>
		</strong>
	</div>
	<span>内容2</span>
	
	<div>1</div>
	<div class="demo">2</div>
	<p class="demo">3</p>
</body>
</html>
```

### 2.权重计算  

**只要写在同一行的选择器，权重值相加**

### 3.分组选择器

```
<html>
<head>
	<title></title>
	<style type="text/css">
		/*分组选择器*/
		em, 
		strong, 
		span{
			background-color: red;
		}

	</style>
</head>
<body>
	<em>1</em>
	<strong>2</strong>
	<span>3</span>
</body>
</html>
```

### 4.css基础属性

**font:**  
a.font-size:12px;  --> 默认16px; 设置的是高  
b.font-weight:bold;--> 100 200 -- 900  
c.font-style:italic; --> 斜体  
d.font-family:arial; --> 字体  
f.line-height:16px; --> 单行文本所占高度  
g.text-indent:2em; --> 首行缩进  
h.text-decoration:none; -->线  

**em:**1 em = 1 font-size;  

****

border:10px solid black;  

### 5.设置颜色

a.土鳖式(纯英文单词) green  
b.颜色代码 #ff4400 每两位都一样可以简化#f40  
c.颜色函数 rgb(255,255,255)  
d.透明色：transparent;  

### 6.伪类选择器  

```
a:hover{
}
```


## css企业开发经验、习惯，盒子模型，层模型  

### 1.css企业开发经验

a.文本垂直居中，line-height = 容器高度  
b.display  

```
	
```

**c.开发：先定义功能再选用样式**  

### 2.盒子模型  

a.盒子的三大部分：  
盒子壁 border  
内边距 padding  
外边距 margin **body默认8px**  
盒子内容 width + height  

### 3.定位 position  

a.absolute; 脱了原来位置进行定位：层模型,**相对最近可定位的父级进行定位，如果没有可定位的父级，相对于文档定位**  

```
left(right)
top(button)
```

b.relative; 保留原来位置进行定位：层模型，**相对于原来的位置进行定位**  

c.fixed; 固定定位

**d.用relative进行参照，用absolute进行定位**  

f.居中：

```
position:absolute;
left:50%;
top:50%;
margin-left:-50%*width;
margin-top:-50%*top;
```

g.z-index:1; 层定位  

h.border-radius:50%    

i.两栏布局：一个div固定宽高，另一个div固定高margin另一个div宽，先写right  

### 4.经典bug -- bfc 

a.margin塌陷：父子嵌套的元素，垂直方向的margin，一起取最大值  

**b.bfc: block format context **  

```

```

```
<!DOCTYPE html>
<html>
<head>
	<title></title>
	<style type="text/css">
	* {
		margin: 0;
		padding: 0;
	}

	.wrapper {
		margin-left: 100px;
		margin-top: 100px;
		width: 100px;
		height: 100px;
		background-color: black;
		/*1.添加border，不现实
		border-top: 1px solid red;*/
		/*2.bfc 哪个没影响就用哪一个*/
		/*overflow:hidden;*//*溢出部分隐藏*/
		/*display:inline-block;*/
		/*float:left/right;*/
		/*position:absolute;*/
	}

	.content {
		margin-left: 50px;
		margin-top: 150px;
		width: 50px;
		height: 50px;
		background-color: green;
	}

	</style>
</head>
<body>
	<div class="wrapper">
		<div class="content"></div>
	</div>
	
</body>
</html>
```

### 5.正常情况下区域不能共用  


### 6.margin合并(兄弟元素，margin-button和margin-top共用一块区域):不解决，注意即可  

### 7.浮动模型  

```
<html>
<head>
	<title></title>
	<style type="text/css">
	* {
		margin: 0;
		padding: 0;
	}

	
	 
	/*demo看不到.box，发生了层叠*/
	.box {
		float: left;
		width: 100px;
		height: 100px;
		background-color: black;
		opacity: 0.5;
	}

	.demo {
		width: 100px;
		height: 150px;
		background-color: green;
	}
	/*.wrapper看不到.content，高度自适应为0*/
	.wrapper {
		border: 1px solid black;
	}
	
	.content {
		float: left;
		color: #fff;
		background-color: black;
		width: 100px;
		height: 100px;
	}
	/*撑开父级的方法·1
	p {
		/*清除浮动流
		clear: both;
	}*/
	/*撑开父级的方法·2*/
	.wrapper::after {
		content: "";
		display: block;
		/**/
		clear: both;
	}
	</style>
</head>
<body>
	
	<div class="box"></div>
	<div class="demo"></div>
	
	<div class="wrapper">
		<div class="content">1</div>
		<div class="content">2</div>
		<div class="content">3</div>
		
	</div>

</body>
</html>
```

**a.浮动元素产生了浮动流**
所有产生了浮动流的元素，块级元素看不到他们，
产生了bfc的元素和文本类属性(inline)的元素以及文本都能看到浮动元素  
**b.clear: both; 清除浮动的元素必须是块级元素**

### 8.伪元素  

**伪元素存在所有标签里面**  

```
<html>
<head>
	<title></title>
	<style type="text/css">
	* {
		margin: 0;
		padding: 0;
	}

	span::before {
		content: "啥";
	}
	span::after {
		content: "哈？";
	}

	</style>
</head>
<body>
	<span>
		为天地立心
	</span>

</body>
</html>
```

### 9.扩展  

**凡是设置了position:abolute; float:left/right;的元素，打内部把元素转换成inline-block**  

**float最早用于报纸布局，文字包裹图片(给图片添加float)**


----

## 溢出容器，要打点展示

```
<html>
<head>
	<title></title>
	<style type="text/css">
	* {
		margin: 0;
		padding: 0;
	}
	p {
		width: 300px;
		height: 20px;
		line-height: 20px;
		border: 1px solid red;
		
		/*单行文本 溢出文字隐藏*/
		white-space: nowrap;/*禁止换号*/
		overflow: hidden;   /*溢出隐藏*/
		text-overflow: ellipsis;/*溢出文字打点*/

	}
	</style>
</head>
<body>
	
	<p>
		天天想你，天天问自己，到什么时候才能忘记你
	</p>
</body>
</html>
```

**单行文字溢出处理：**  
/*单行文本 溢出文字隐藏*/  
white-space: nowrap;/*禁止换号*/  
overflow: hidden;   /*溢出隐藏*/  
text-overflow: ellipsis;/*溢出文字打点*/  

## 背景图片处理

**浏览器不加载css怎么处理**
![](https://raw.githubusercontent.com/XuZhuohao/picture/master/UI/CSS/css.png)

## 其他  

**行级元素只能嵌套行级元素**  
**块级元素可以嵌套任何元素**  
**P标签不能嵌套div标签，p元素会被div风格成两组p标签**  
**a标签不能嵌套a标签**  
**凡是带有inline的元素都有文本特点**  
**凡是设置了position: abolute; float: left/right;的元素，打内部把元素转换成inline-block**  
**行级块元素底对齐，单行级块元素中有文字，外部文字与其中的文字底对齐**  
**inherit关键字:让指定的标签，显示该属性的原设置。**

git game

start game

1.配置文件

1.1 配置命令

kafka quick start

1. 安装

1.1 下载解压

DFS 和 HDFS

DFS (Distributed file system)

css引入css基础选择器选择器权重

1.CSS style sheet 层叠样式表格

2.引入：

1.CSS
style sheet 层叠样式表格