git usage 0x00 workflow git 的工作流程，已 k8s devel 的开发者文档里面图来说明：
首先在 fork 代码，然后 clone 到本地，创建分支并修改代码，commit 发 PR 或者 rebase/fetch 别人的代码后修改发 PR.
0x01 tips
Merge another branch of the same git-repo
Pick up a specific commit from another branch
1 git cherry-pick commit-name
Merge a branch from another local git repo
1 git pull /path/to/git-repo branch-name
Rebase your commits
1 git rebase -i commit-nameˆ
Rebase a branch onto master
1 git rebase –onto master –root
Delete a remote branch
Example of generate and release kernel patches
Generate patches1 git format-patch -s –cover-letter –thread commit1ˆ..commit2 –cc="Name <user@example.com>"
Check&fix up your patches Documentation/SubmitChecklist, script/checkpatch.pl cleanfile
Release your patches Config send-email:1 git config, man git-send-email(Sending)
Get maintainers:1 ./scripts/get maintainer.pl
Send out your patch:1 git send-email –to=”LKML <linux-kernel@vger.kernel.org>” –cc="Maintainers’ Email Address"
0x10 filter-branch git 的本质是内容寻址文件系统，有时候需要 undo 操作消除敏感信息是不够的，关于更多 git 底层信息参考 progit^progit .
0x11 Clear sensitive files 1 2 3 4 5 6 7 8 9 10 11 12 13 $ ls password password $ git filter-branch --index-filter "git rm -rf --cached --ignore-unmatch password" --prune-empty -- --all Rewrite be0acf636754aea731c0b1f285142143dbf0275f (2/3) (0 seconds passed, remaining 0 predicted) rm 'password' Rewrite c3cc58dc9ebe7cf1f3187a0a6172e1bb274b3921 (3/3) (0 seconds passed, remaining 0 predicted) rm 'password' Ref 'refs/heads/master' was rewritten $ ls chcon init $ git show 100644 fatal: ambiguous argument '100644': unknown revision or path not in the working tree. Use '--' to separate paths from revisions, like this: 'git <command> [<revision>...] -- [<file>...]'
0x12 remove the largest file 通过 git 阅读索引文件 (拓展名.idx),确认哪个 object 最大
1 2 3 4 $ git verify-pack -v .git/objects/pack/pack-f92ea95d8f9a18dd42335fc3e3bd25feb8ed5ef8.idx | sort -k 3 -n | tail -3 1d07197534891b5d45286850f7202dc1f84beceb blob 2885745 2873595 11242780 61ba4967a562aaff8d1208981a2f1be968c969fd blob 8929280 3255190 3940716 353a62618f023052c25db90d5c3f6725cadfbd95 blob 9263612 2936691 73858887
查看体积最大的 hash 属于哪个文件
1 2 $ git rev-list --objects --all | grep 353a62618f023052c25db90d5c3f6725cadfbd95 353a62618f023052c25db90d5c3f6725cadfbd95 vendor/github.com/go-openapi/spec/debug.test
确认该文件属于哪个 commit
1 2 $ git --no-pager log --pretty=oneline --branches -- vendor/github.com/go-openapi/spec/debug.test da1f2c61c603e1cadc89e2cc690d46d2f972501e Update vendor packages (#1378)
要移除这个文件需要利用 filter-barch 重写自da1f2c61c603e1cadc89e2cc690d46d2f972501e的全部历史，注意 commitid 后面的^与..
1 2 3 4 5 6 7 8 9 10 $ git filter-branch --index-filter 'git rm --cached --ignore-unmatch vendor/github.com/go-openapi/spec/debug.test' -- da1f2c61c603e1cadc89e2cc690d46d2f972501e^.. Rewrite da1f2c61c603e1cadc89e2cc690d46d2f972501e (1/8) (0 seconds passed, remaining 0 predicted) rm 'vendor/github.com/go-openapi/spec/debug.test' Rewrite 8c83a03a1b84fd18830b8bfaf1ea09ba5cc93e78 (2/8) (0 seconds passed, remaining 0 predicted) rm 'vendor/github.com/go-openapi/spec/debug.test' Rewrite 3fe627bb58a2f081a7976a13dd0b014c5c882bcb (3/8) (0 seconds passed, remaining 0 predicted) rm 'vendor/github.com/go-openapi/spec/debug.test' Rewrite dd3ef7d823313445774d2ed577f67d2da37a1568 (4/8) (1 seconds passed, remaining 1 predicted) rm 'vendor/github.com/go-openapi/spec/debug.test' Rewrite 0b0bafce155f20be369f35da045fb6338bf38e24 (4/8) (1 seconds passed, remaining 1 predicted) rm 'vendor/github.com/go-openapi/spec/debug.test' Rewrite fd18f0e6895bbfc144051e928d8c77a110fb2978 (4/8) (1 seconds passed, remaining 1 predicted) rm 'vendor/github.com/go-openapi/spec/debug.test' Rewrite 69e2d04e0f4f69f9c6c0c5d24b4b6b07490d347d (4/8) (1 seconds passed, remaining 1 predicted) rm 'vendor/github.com/go-openapi/spec/debug.test' Rewrite 645191d3ff4cf9e898c9e5796b86dc010c095630 (4/8) (1 seconds passed, remaining 1 predicted) rm 'vendor/github.com/go-openapi/spec/debug.test' Ref 'refs/heads/master' was rewritten
清理 reflog 对象
1 2 3 4 5 6 7 8 $ rm -Rf .git/refs/original$ rm -Rf .git/logs/$ git gc Counting objects: 36023, done. Delta compression using up to 4 threads. Compressing objects: 100% (18106/18106), done. Writing objects: 100% (36023/36023), done. Total 36023 (delta 16535), reused 35996 (delta 16515)
对比一下清理前后，其中size-pack是以 kB 为单位进行记录大小的。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 $ git count-objects -v count: 0 size: 0 in-pack: 36023 packs: 1 size-pack: 77904 prune-packable: 0 garbage: 0 size-garbage: 0 $ git count-objects -v count: 0 size: 0 in-pack: 36003 packs: 1 size-pack: 77911 prune-packable: 0 garbage: 0 size-garbage: 0
