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Git 和项目代码分析

Git 是一个版本控制系统，对纯文本（代码等）有很好的支持。

Git 是一个内容寻址文件系统

在 Git 里（.git 文件夹，对象（文件、提交等）都是 hash 并存储在以 hash 索引的文件夹结构里，任何相同内容的对象都只存在一份。因此你可以查询某文件是不是在 Git 中，如果在，在哪里。

更新 Windows 上 的 Git

2.16.1 以后版本的 Git，直接 git update-git-for-windows。

参考：https://stackoverflow.com/questions/13790592/how-to-upgrade-git-on-windows-to-the-latest-version

检出一个标签（tag）

git checkout tags/<tag_name> 或者 git checkout <tag_name>，推荐第一个因为可能有同名标签。

Git Merge Base

git merge-base --all <commit_1> <commit_2>
git merge-base --all --octopus <commit_1> <commit_2> <commit_3> ...

Add --all to list all possible ancestors (equally good).

If you have more than two commits, you can add ----octopus otherwise it is the ancestor of the first commit, and a hypothetical commit which is a merge of all other commits.

Examples:

         o---o---o---B
        /
---o---1---o---o---o---A
git merge-base A B = 1

       o---o---o---o---C
      /
     /   o---o---o---B
    /   /
---2---1---o---o---o---A
git merge-base --octopus A B C = 2

---1---o---A
    \ /
     X
    / \
---2---o---o---B
git merge-base --all A B = 1 2

Git Rebase

git rebase essentially replays the changes of commits.

git rebase base change will first switch to change, replay changes in change after the merge base of change and base onto base and commit these new derived commits (hashes are different because the contents are different) in change.

git rebase --onto new_base base change is similar, except that it replays the changes onto new_base instead of base.

Examples:

      A---B---C topic
     /
D---E---F---G master
git rebase master topic =>
              A'--B'--C' topic
             /
D---E---F---G master

o---o---o---o---o  master
     \
      o---o---o---o---o  next
                       \
                        o---o---o  topic
git rebase --onto master next topic =>
o---o---o---o---o  master
    |            \
    |             o'--o'--o'  topic
     \
      o---o---o---o---o  next

If there is any conflict, it will enter the interactive rebase mode. You can git rebase --abort. Or you can resolve conflicts, git add them and git rebase --contibue, it will finish the rebase or let you resolve remaining conflicts.

It seems that the default interactive rebase resolves two commits each round but you can git rebase --edit-todo to adjust the range.

Mail map

In .mailmap you can specify canonical names and emails to be displayed in git log and other places. You can use this to handle wrong names or emails in commits.

# Based on <commit@email>
Display Name <commit@email>  # Replace name
<display@email> <commit@email>  # Replace email
Display Name <display@email> <commit@email>  # Replace both

# Based on both <Commit Name> and <commit@email>
Display Name <Commit Name> <commit@email>  # Replace name
<display@email> Commit Name <commit@email>  # Replace email
Display Name <display@email> Commit Name <commit@email>  # Replace both

工具

Git 统计

git-quick-stats

# Install
apt install git-quick-stats
brew install git-quick-stats

# Statistics
export _GIT_SINCE="2021-01-16"
git quick-stats --detailed-git-stats

Git 总 commit 数

git rev-list --count HEAD
git rev-list --count main

代码行数分析

Cloc

# 安装
sudo apt install cloc
brew install cloc

# 统计行数
cloc .
cloc <some_folder>
cloc <some_file>
cloc --exclude-dir=<dir1>,<dir2> <some_folder>

搜索历史文件文本

https://git-scm.com/book/en/v2/Git-Tools-Searching

# 只能搜索某个 revision
git grep [<options>] [-e] <pattern> [<rev>...] [[--] <path>...]
git grep "Shao Wang" master

# 可以搜索整个历史
git log [<options>] [<revision-range>] [[--] <path>...]
git log -S "Shao Wang"