Git 各指令的本質，真是通俗易懂啊

{"type":"doc","content":[{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"前言","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"作爲當前世界上最強大的代碼管理工具Git相信大家都很熟悉，但據我所知有很大一批人停留在clone、commit、pull、push...的階段，是不是對rebase心裏沒底只敢用merge？","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"碰見版本回退就抓瞎？別問我怎麼知道的，問就是：“我曾經就是這樣啊～～”。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"針對這些問題，今天我就將這幾年對Git的認知和理解分享出來，儘可能的從本質去講解Git，幫助你一步一步去了解Git的底層原理，相信讀完本篇文章你便可以換種姿態，更加風騷得使用Git各種指令。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"基本概念","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"1.1 Git的優勢","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Git是一個分佈式代碼管理工具，在討論分佈式之前避免不了提及一下什麼是中央式代碼管理倉庫","attrs":{}}]},{"type":"blockquote","content":[{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"中央式：所有的代碼保存在中央服務器，所以提交必須依賴網絡，並且每次提交都會帶入到中央倉庫，如果是協同開發可能頻繁觸發代碼合併，進而增加提交的成本和代價。最典型的就是svn","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"分佈式：可以在本地提交，不需要依賴網絡，並且會將每次提交自動備份到本地。每個開發者都可以把遠程倉庫clone一份到本地，並會把提交歷史一併拿過來。代表就是Git","attrs":{}}]}]}],"attrs":{}}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"那Git相比於svn有什麼優勢呢？","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"打個比方：\"巴拉巴拉寫了一大堆代碼，突然發現寫的有問題，我想回到一個小時之前\"，對於這種情況Git的優勢就很明顯了，因爲commit的成本比較小並且本地會保存所有的提交記錄，隨時隨刻可以進行回退。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在這並不是說svn的不能完成這種操作，只是Git的回退會顯得更加的優雅。Git相比於中央式工具還有很多優點，就不一一列舉了，感興趣的可自行了解。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"1.2 文件狀態","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在Git中文件大概分爲三種狀態：已修改（modified）、已暫存（staged）、已提交（committed）","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"修改","attrs":{}},{"type":"text","text":"：Git可以感知到工作目錄中哪些文件被修改了，然後把修改的文件加入到modified區域","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"暫存","attrs":{}},{"type":"text","text":"：通過add命令將工作目錄中修改的文件提交到暫存區，等候被commit","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"提交","attrs":{}},{"type":"text","text":"：將暫存區文件commit至Git目錄中永久保存","attrs":{}}]}]}],"attrs":{}},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"1.3 commit節點","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"爲了便於表述，本篇文章我會通過節點代稱commit提交","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在Git中每次提交都會生成一個節點,而每個節點都會有一個哈希值作爲唯一標示，多次提交會形成一個線性節點鏈（不考慮merge的情況），如圖1-1","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/06/06691b4778b7a2d0a045a6186b6f048e.webp","alt":"圖片","title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"節點上方是通過 SHA1計算的哈希值","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"C2節點包含C1提交內容,同樣C3節點包含C1、C2提交內容","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"1.4 HEAD","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"HEAD是Git中非常重要的一個概念，你可以稱它爲指針或者引用，它可以指向任意一個節點，並且指向的節點始終爲當前工作目錄，換句話說就是當前工作目錄(也就是你所看到的代碼)就是HEAD指向的節點。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"還以圖1-1舉例，如果HEAD指向C2那工作目錄對應的就是C2節點。具體如何移動HEAD指向後面會講到，此處不要糾結。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"同時HEAD也可以指向一個分支，間接指向分支所指向的節點。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"1.5 遠程倉庫","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"雖然Git會把代碼以及歷史保存在本地，但最終還是要提交到服務器上的遠程倉庫。通過clone命令可以把遠程倉庫的代碼下載到本地，同時也會將提交歷史、分支、HEAD等狀態一併同步到本地，但這些狀態並不會實時更新，需要手動從遠程倉庫去拉取，至於何時拉、怎麼拉後面章節會講到。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通過遠程倉庫爲中介，你可以和你的同事進行協同開發，開發完新功能後可以申請提交至遠程倉庫，同時也可以從遠程倉庫拉取你同事的代碼。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"注意點","attrs":{}}]},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"因爲你和你的同事都會以遠程倉庫的代碼爲基準，所以要時刻保證遠程倉庫的代碼質量，切記不要將未經檢驗測試的代碼提交至遠程倉庫","attrs":{}}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"2 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經歷了千辛萬苦終於發佈了v1.0版本，由於需求緊急v1.0上線之後便馬不停蹄的開始v1.1，正當你開發的興起時，QA同學說用戶反饋了一些bug，需要修復然後重新發版，修復v1.0肯定要基於v1.0的代碼，可是你已經開發了一部分v1.1了，此時怎麼搞？","attrs":{}}]}]}],"attrs":{}}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"面對上面的問題通過引入分支概念便可優雅的解決，如圖2-1","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/2a/2af466b26b17dadea966e3b844d11a34.webp","alt":"圖片","title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"blockquote","content":[{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"先看左邊示意圖，假設C2節點既是v1.0版本代碼，上線後在C2的基礎上新建一個分支ft-1.0","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"再看右邊示意圖，在v1.0上線後可在master分支開發v1.1內容，收到QA同學反饋後提交v1.1代碼生成節點C3，隨後切換到ft-1.0分支做bug修復，修復完成後提交代碼生成節點C4，然後再切換到master分支併合並ft-1.0分支，到此我們就解決了上面提出的問題","attrs":{}}]}]}],"attrs":{}}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"除此之外利用分支還可以做很多事情，比如現在有一個需求不確定要不要上線，但是得先做，此時可以單獨創建一個分支開發該功能，等到啥時候需要上線直接合併到主分支即可。分支適用的場景很多就不一一列舉了。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"注意點","attrs":{}}]},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"當在某個節點創建一個分支後，並不會把該節點對應的代碼複製一份出來，只是將新分支指向該節點，因此可以很大程度減少空間上的開銷。一定要記着不管是HEAD還是分支它們都只是引用而已，量級非常輕","attrs":{}}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","marks":[{"type":"italic","attrs":{}}],"text":"3 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