Git技法:.gitignore、移除暂存与撤销修改

1. .gitignore常见项目添加

1.1 .gitignore模板

.gitignore针对每个语言都有对应的模板,在GitHub创建项目时就可以选择(你可以在GitHub提供的.gitignore模板大全中找到它)。如Python语言的.gitignore模板如下:

# Byte-compiled / optimized / DLL files
__pycache__/
*.py[cod]
*$py.class

# C extensions
*.so

# Distribution / packaging
.Python
build/
develop-eggs/
dist/
downloads/
eggs/
.eggs/
lib/
lib64/
parts/
sdist/
var/
wheels/
pip-wheel-metadata/
share/python-wheels/
*.egg-info/
.installed.cfg
*.egg
MANIFEST

# PyInstaller
#  Usually these files are written by a python script from a template
#  before PyInstaller builds the exe, so as to inject date/other infos into it.
*.manifest
*.spec

# Installer logs
pip-log.txt
pip-delete-this-directory.txt

# Unit test / coverage reports
htmlcov/
.tox/
.nox/
.coverage
.coverage.*
.cache
nosetests.xml
coverage.xml
*.cover
*.py,cover
.hypothesis/
.pytest_cache/

# Translations
*.mo
*.pot

# Django stuff:
*.log
local_settings.py
db.sqlite3
db.sqlite3-journal

# Flask stuff:
instance/
.webassets-cache

# Scrapy stuff:
.scrapy

# Sphinx documentation
docs/_build/

# PyBuilder
target/

# Jupyter Notebook
.ipynb_checkpoints

# IPython
profile_default/
ipython_config.py

# pyenv
.python-version

# pipenv
#   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.
#   However, in case of collaboration, if having platform-specific dependencies or dependencies
#   having no cross-platform support, pipenv may install dependencies that don't work, or not
#   install all needed dependencies.
#Pipfile.lock

# PEP 582; used by e.g. github.com/David-OConnor/pyflow
__pypackages__/

# Celery stuff
celerybeat-schedule
celerybeat.pid

# SageMath parsed files
*.sage.py

# Environments
.env
.venv
env/
venv/
ENV/
env.bak/
venv.bak/

# Spyder project settings
.spyderproject
.spyproject

# Rope project settings
.ropeproject

# mkdocs documentation
/site

# mypy
.mypy_cache/
.dmypy.json
dmypy.json

# Pyre type checker
.pyre/

1.2 添加更多的.gitignore项目

但是这些往往是不够的的。如我们在Mac系统下用VSCode开发,那么常常还需要添加以下项目:

# IDE - VSCode
.vscode/

# OS generated files
.DS_Store

其中.vscode/表示忽略.vscode这个包含项目配置文件的隐藏目录(注意是包括目录一起忽略,这个和Linux下诸如cp test/ .这类命令的语义有区别,参加我的博客《Linux:文件解压、复制和移动的若干坑》),.DS_Store表示忽略掉Mac操作系统下存储目录自定义属性的隐藏文件。

此外,我们再以机器学习相关的项目为例子,数据(放在data目录下)和模型(放在model目录下)通常异常巨大,我们并不想将它们放到项目文件夹下,因此我们可能倾向于添加如下的项目:

# data files
data/*

# model files
model/*

data/*model/*语义上表示忽视data目录下所有文件与model目录下所有文件及子目录(不包括datamodel目录本身)。但是我们会发现,实际上空的datamodel目录并没有成功git add到项目中

(base) orion-orion@MacBook-Pro Learn-Git % git add data                  
(base) orion-orion@MacBook-Pro Learn-Git % git add model                 
(base) orion-orion@MacBook-Pro Learn-Git % git status                    
On branch main
Your branch is ahead of 'origin/main' by 1 commit.
  (use "git push" to publish your local commits)

nothing to commit, working tree clean

这是因为空目录不会称为Git版本控制系统跟踪(track)。但是如果我们想保存datamodel的目录架构呢?很简单,我们只需要在datamodel目录下添加.gitkeep目录即可,然后将在.gitignore文件中对.gitkeep进行反选(即不忽视):

# data files
data/*
!data/.gitkeep

# model files
model/*
!model/.gitkeep

可以看到由于隐藏文件的存在,现在空目录能够正常git add了:

(base) orion-orion@MacBook-Pro Learn-Git % git add data 
(base) orion-orion@MacBook-Pro Learn-Git % git add model
(base) orion-orion@MacBook-Pro Learn-Git % git status   
On branch main
Your branch is ahead of 'origin/main' by 1 commit.
  (use "git push" to publish your local commits)

Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
        new file:   data/.gitkeep
        new file:   model/.gitkeep

但是需要注意,如果这样写就没用:

# data files
data/
!data/.gitkeep

因为data/表示将data目录本身也忽略了,Git根本就不会去查看该目录,以致.gitkeep文件也就不起作用了。

额外提一下,如果我们仅仅希望忽略掉data目录下的.csv文件,可以这样写:

# data files
data/*.csv

2. 移除已暂存(staged)的文件

2.1 关于跟踪与暂存

在Git中,一个文件可能在这三种区域中:工作目录(Working Directory),暂存区(Staging Area,也称索引index),Git仓库(可视为一棵提交树committed tree)。三者关系如下图所示:
《Git技法:.gitignore、移除暂存与撤销修改》

当我们将文件添加到项目目录中时,我们其实是在将其添加到工作目录中。

一旦一个目录或文件被git add了一次,那么它就会被跟踪(track)并加入暂存区。此后再对其进行修改,Git会提醒你Changes not staged for commitmodified: README.md,需要再次运行git add将其暂存(staged):

(base) orion-orion@MacBook-Pro Learn-Git % echo "new version" > README.md 
(base) orion-orion@MacBook-Pro Learn-Git % git status
On branch main
Your branch is ahead of 'origin/main' by 2 commits.
  (use "git push" to publish your local commits)

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
        modified:   README.md

no changes added to commit (use "git add" and/or "git commit -a")

而文件的所谓的未跟踪(untracked)、未修改(unmodified)、已修改(modified)、已暂存(staged)四种状态的关系如下所示:

《Git技法:.gitignore、移除暂存与撤销修改》

2.2 清除已暂存的文件

现在假设我们搞忘了编写.gitignore,然后已经用了git add -Agit add .命令目录下所有文件及子目录都暂存了(在Git 2.0中git add -Agit add .命令等效)。而其中有很大的日志文件或一些诸如*.a的编译文件,我们如何将这些文件从暂存区域移除以取消跟踪呢?可以用git rm --cached命令完成此项工作,如:

git rm --cached README.md

注意要带上选项--cached,而不仅仅是git rmgit rm除了从暂存区域移除外,还会将磁盘上的文件也一起删了。关于参数选项可以参见我的博客《Linux:可执行程序的Shell传参格式规范 》

使用该命令效果如下:

(base) orion-orion@MacBook-Pro Learn-Git % git rm --cached README.md 
rm 'README.md'
(base) orion-orion@MacBook-Pro Learn-Git % git status               
On branch main
Your branch is ahead of 'origin/main' by 2 commits.
  (use "git push" to publish your local commits)

Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
        deleted:    README.md

注意到Changes to be committed:deleted: README.md,这说明当我们使用git rm --cached并commit后, 相关的文件还会被从committed tree中移除。如果我们只想移除出暂存区,可以使用下列命令:

 git reset HEAD README.md

该命令等同 git reset --mixed HEAD README.md(默认参数为--mixed,还有个参数为--hard,我们放在3.3节讲)。使用后效果如下:

(base) orion-orion@MacBook-Pro Learn-Git % git reset HEAD *.md     
Unstaged changes after reset:
M       README.md
(base) orion-orion@MacBook-Pro Learn-Git % git status              
On branch main
Your branch is ahead of 'origin/main' by 2 commits.
  (use "git push" to publish your local commits)

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
        modified:   README.md

no changes added to commit (use "git add" and/or "git commit -a")

注意到Changes not staged for commit: modified: README.md。说明该命令只是将README.md移除暂存区,但是上次对README.md的commit还在(即撤销最近的一次commit之后的变化)。

如果要递归地将当前目录下的所有文件及子目录移除出暂存区(与commit tree),可以这样写:

git rm -r --cached . 

注意这个命令非常危险和暴力,一般还是建议指定具体的目录或文件名。

3. 追加与撤销git commit操作

3.1 commit历史查看

git log命令可以看到项目的git commit历史:

(base) orion-orion@MacBook-Pro Learn-Git % git log
commit 37a35d36eaf8b56c9e7b719c3c7576f3251cee36 (HEAD -> main)
Author: orion-orion <orion-orion@foxmail.com>
Date:   Mon May 23 14:15:21 2022 +0800

    modify .gitignore

commit ab7bf6e2c400c8d775cc3bc56928c7748c63c8f8
Author: orion-orion <orion-orion@foxmail.com>
Date:   Mon May 23 10:08:08 2022 +0800

    add .gitignore

commit 146c68e12fd2aebed8b38dd5cf95621f800fe4aa (origin/main, origin/HEAD)
Author: 猎户座 <46917784+orion-orion@users.noreply.github.com>
Date:   Sun May 22 09:48:22 2022 +0800

    Initial commit

默认不用任何参数的话,git log会按提交时间列出所有的更新,最近的更新排在最上面。 正如你所看到的,这个命令会列出每个提交的 SHA-1 校验和、作者的名字和电子邮件地址(如果电子邮件名为<46917784+orion-orion@users.noreply.github.com>,说明你在GitHub中将邮件名设置为私有的了,需要去修改一下)、提交时间以及提交说明。

3.2 追加commit操作

现在我们又对.gitignore进行了修改。但是我们不想又commit一次,而想将其合并在最后一次的modify .gitignore里,使commit记录更为精简。我们可以用以下命令:

(base) orion-orion@MacBook-Pro Learn-Git % git add .gitignore
(base) orion-orion@MacBook-Pro Learn-Git % git commit --amend

并在commit信息的编辑界面写入modify .gitignore

modify .gitignore

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# Date:      Mon May 23 14:15:21 2022 +0800
#
# On branch main
# Your branch is ahead of 'origin/main' by 2 commits.
#   (use "git push" to publish your local commits)
#
# Changes to be committed:
#       modified:   .gitignore
#       new file:   data/.gitkeep
#       new file:   model/.gitkeep
#
# Changes not staged for commit:
#       modified:   README.md
#
                          
:wq!

可以看到总的commit记录没变,所显示的最后一次commit记录的时间也没变,但新的修改已经追加进去了(SHA-1 校验和发生了变化):

(base) orion-orion@MacBook-Pro Learn-Git % git log           
commit a0dfeff409494165bdff60c27b24fad2bc0ed0ad (HEAD -> main)
Author: orion-orion <orion-orion@foxmail.com>
Date:   Mon May 23 14:15:21 2022 +0800

    modify .gitignore

commit ab7bf6e2c400c8d775cc3bc56928c7748c63c8f8
Author: orion-orion <orion-orion@foxmail.com>
Date:   Mon May 23 10:08:08 2022 +0800

    add .gitignore

commit 146c68e12fd2aebed8b38dd5cf95621f800fe4aa (origin/main, origin/HEAD)
Author: 猎户座 <46917784+orion-orion@users.noreply.github.com>
Date:   Sun May 22 09:48:22 2022 +0800

    Initial commit

3.3 撤销git commit操作

现在我们想撤销git commit的操作。我们回到git reset命令。不过现在我们需要使用git reset --hard方法:

(base) orion-orion@MacBook-Pro Learn-Git %  git reset --hard HEAD^1
HEAD is now at ab7bf6e add .gitignore
(base) orion-orion@MacBook-Pro Learn-Git % git log                 
commit ab7bf6e2c400c8d775cc3bc56928c7748c63c8f8 (HEAD -> main)
Author: orion-orion <orion-orion@foxmail.com>
Date:   Mon May 23 10:08:08 2022 +0800

    add .gitignore

commit 146c68e12fd2aebed8b38dd5cf95621f800fe4aa (origin/main, origin/HEAD)
Author: 猎户座 <46917784+orion-orion@users.noreply.github.com>
Date:   Sun May 22 09:48:22 2022 +0800

    Initial commit

命令中的HEAD^1意思为将commit记录回退到上上次提交后的状态,HEAD^2以此类推。
不过大家必须注意,--hard 标记是reset命令唯一的危险用法,它也是 Git 会真正地销毁数据的仅有的几个操作之一。 其他任何形式的reset调用都可以轻松撤消,但是--hard选项不能,因为它强制覆盖了工作目录中的文件。

参考

    原文作者:orion-orion
    原文地址: https://www.cnblogs.com/orion-orion/p/16303308.html
    本文转自网络文章,转载此文章仅为分享知识,如有侵权,请联系博主进行删除。
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