首先來(lái)看下.git目錄：

├── HEAD
├── branches
├── index
├── logs
│   ├── HEAD
│   └── refs
│       └── heads
│           └── master
├── objects
│   ├── 88
│   │   └── 23efd7fa394844ef4af3c649823fa4aedefec5
│   ├── 91
│   │   └── 0fc16f5cc5a91e6712c33aed4aad2cfffccb73
│   ├── 9f
│   │   └── 4d96d5b00d98959ea9960f069585ce42b1349a
│   ├── info
│   └── pack
└── refs
    ├── heads
    │   └── master
    └── tags

• description用于GitWeb程序
• config 配置特定于該倉(cāng)庫(kù)的設(shè)置
• hooks 放置客戶端或服務(wù)端的hook腳本
• HEAD 指明當(dāng)前處于哪個(gè)分支
• objectsGit對(duì)象存儲(chǔ)目錄
• refs Git引用存儲(chǔ)目錄
• branches 放置分支引用的目錄
  每次git-add都會(huì)生成一個(gè)Git對(duì)象，稱為 blob對(duì)象，存放在objects目錄下。

這個(gè)blob 對(duì)象里保存的是什么呢?

Git在add文件時(shí)，會(huì)把文件完整的保存成一個(gè)新的 blob 對(duì)象。通過(guò) git-gc打包或者每次git-push的時(shí)候Git都會(huì)自動(dòng)執(zhí)行一次打包過(guò)程，將blob對(duì)象合并成一個(gè)包文件，同時(shí)會(huì)生成一個(gè)索引文件，索引文件中包含了每個(gè)blob對(duì)象在包文件中的偏移信息，Git在打包的過(guò)程中使用了增量編碼方案，只保存blob對(duì)象的不同版本之間的差異，這使得倉(cāng)庫(kù)會(huì)瘦身。

既然Git會(huì)對(duì)Blob對(duì)象進(jìn)行合并優(yōu)化，那么objects文件夾為什么還會(huì)那么大呢?

因?yàn)楫?dāng)Blob對(duì)象在合并時(shí)不能對(duì).a進(jìn)行差異化比較，所以每次在添加.a文件時(shí)，都會(huì)保存一份.a文件，用于后續(xù)代碼還原時(shí)使用。
所以當(dāng)頻繁更換.a文件時(shí)，objects下的pack文件會(huì)越來(lái)越大。雖然這個(gè).a文件后續(xù)可能用不到刪除了，但是pack中的這個(gè).a文件的緩存還是會(huì)一直存在。

刪除pack中無(wú)用的大文件緩存

1、首先先找出git中較大的五個(gè)提交記錄文件：

git verify-pack -v .git/objects/pack/pack-*.idx | sort -k 3 -g | tail -5

如果想查看所有的提交記錄可執(zhí)行一下命令：

git rev-list --all

執(zhí)行結(jié)果（當(dāng)前我們以查詢最大的五次做介紹）：

dbad6eb20d31a5aefe132b74b2137cd10105c574 blob   16684712 7287784 86721282
6c858bc93421b2db41dafc2bfd4eb82c77c50266 blob   17504576 8257957 47764046
416088453a2514ada98ba639af3ff298510b4246 blob   22216104 10854126 75719527
f0d8d3b476526af42b4e06f390a1b4925580e99b blob   22435760 10589160 16678516
553ba826b92c9d42acb1e586774ac697661588c9 blob   29814552 12998052 60871184

2、第一行的字母其實(shí)相當(dāng)于文件的id，用以下命令可以找出id對(duì)應(yīng)的文件名：

git rev-list --objects --all | grep dbad6eb20d31a5aefe132b74b2137cd10105c574

執(zhí)行結(jié)果：

dbad6eb20d31a5aefe132b74b2137cd10105c574 Pods/UMengUShare/UShareSDK/SocialLibraries/WeChat/WechatSDK/libWeChatSDK.a

3、找到最大的幾個(gè)文件后，怎么刪除呢？
能夠勝任這個(gè)任務(wù)的命令叫做 filter-branch:

git filter-branch --force --prune-empty --index-filter 'git rm -rf --cached --ignore-unmatch Pods/UMengUShare/UShareSDK/SocialLibraries/WeChat/WechatSDK/libWeChatSDK.a' --tag-name-filter cat -- --all

4、上面代碼執(zhí)行完畢后有可能會(huì)報(bào)以下錯(cuò)誤

WARNING: git-filter-branch has a glut of gotchas generating mangled history
     rewrites.  Hit Ctrl-C before proceeding to abort, then use an
     alternative filtering tool such as 'git filter-repo'
     (https://github.com/newren/git-filter-repo/) instead.  See the
     filter-branch manual page for more details; to squelch this warning,
     set FILTER_BRANCH_SQUELCH_WARNING=1.
Proceeding with filter-branch...

Cannot rewrite branches: You have unstaged changes.

5、如果出現(xiàn)以上錯(cuò)誤可執(zhí)行以下命令 （不報(bào)錯(cuò)則跳過(guò)此步）

git stash

然后重新執(zhí)行移除命令

git filter-branch --force --prune-empty --index-filter 'git rm -rf --cached --ignore-unmatch Pods/UMengUShare/UShareSDK/SocialLibraries/WeChat/WechatSDK/libWeChatSDK.a' --tag-name-filter cat -- --all

執(zhí)行結(jié)果：

WARNING: git-filter-branch has a glut of gotchas generating mangled history
     rewrites.  Hit Ctrl-C before proceeding to abort, then use an
     alternative filtering tool such as 'git filter-repo'
     (https://github.com/newren/git-filter-repo/) instead.  See the
     filter-branch manual page for more details; to squelch this warning,
     set FILTER_BRANCH_SQUELCH_WARNING=1.
Proceeding with filter-branch...

Rewrite 967ff01a8b2bc7d7f6c90630ede38a2135ba5813 (1/41) (0 seconds passed, remaiRewrite 9674de7f9f8ed029785421f2246bb9d41786cc49 (2/41) (0 seconds passed, remaiRewrite e04ab331167f24b7d26d69e169386e690081af74 (3/41) (0 seconds passed, remaiRewrite 997e93fdaff75162eda8e5c6ee6d3265ce61fe96 (4/41) (0 seconds passed, 
Rewrite 429d321e2ee4c54d8d96b35a8e35d021bd8930f1 (35/41) (3 seconds passed, remaining 0 predicted)    rm 'Pods/UMengUShare/UShareSDK/SocialLibraries/WeChat/WechatSDK/libWeChatSDK.a'

Ref 'refs/heads/master' was rewritten
Ref 'refs/remotes/origin/master' was rewritten
WARNING: Ref 'refs/remotes/origin/master' is unchanged
Ref 'refs/stash' was rewritten

6、等命令執(zhí)行完后，要提交到遠(yuǎn)程：

git push --force --all

參考鏈接：http://www.itdecent.cn/p/4f2ccb48da77

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