cs / cpp-programming

5 Version Control

[TOC]

5 Version Control

首先安装 git

shell
sudo apt install git
git --version

然后 configure name 和 email

shell
git config --global user.name "Your NAME here"
git config --global user.email "Your Email here"

5.1 Github Authentication 验证

有两个方法 connect to Github:

  1. SSH Key: a special file that you can use to connect to remote terminals.
  2. Github Personal Tokens Keys: a separate password used just for GitHub.

5.1.1 SSH Keys

如果有下面这些 files 中的一些，你就已经有 SSH Keys 了；如果你 get an error that ~/.ssh does not exist, 那就说明还没有，可以创造一个.

看看有没有：

shell
ls ~/.ssh
...

if error, generate one:

shell
ssh-keygen -t ed25519 -C "your_email@example.com"

Enter. 创建结束.

通过 cat 指令把 pub 文件的内容传给 shell，shell 就会显示出来.

shell
cat ~/.ssh/id_ed25519.pub
# ssh-ed25519 KLBJDjlkaksfadhinoueliwekljhfasdlkjhfdss/asdnfkjlnaksjdfdfnkljdafslF awdeorio@umich.edu.com

把这个结果复制下来，打开 https://github.com/settings/keys ， 而后点击 Add SSH key.

image-20240127213212481

然后就有一个连接到 Github 的 SSH key 了.

WARNING: Do not share your private key with anyone! It’s the file that looks like id_ed25519！

Test your connection:

shell
ssh -T git@github.com
Hi awdeorio! You've successfully authenticated, but GitHub does not provide shell access.

5.1.2 Personal Acces Token

A Personal Access Token is an alternative to SSH Keys.

直接 Login to GitHub. Navigate to Profile > Settings > Developer Settings > Tokens (classic).

直接 Generate 一个，记得 check only the repo box.

image-20240127215253670

然后 Copy 下来.

5.2 Create a local repository

5.2.1 给 directory 添加一个 .gitignore 文件

这里的这个 .gitignore 是一个 pre-configured 能够 work with most C++ projects 的，因而 280/281 的 pro 都能用.

shell
pwd
# /Users/awdeorio/Developer/eecs280/p2-cv
wget https://eecs280staff.github.io/tutorials/dot_gitignore_sample -O .gitignore
ls -A
# .gitignore

5.2.2 Initialize repo

shell
git init
#Initialized empty Git repository in /Users/awdeorio/Developer/eecs280/p2-cv/.git/
git status
#On branch main

#Untracked files:

#	.gitignore
#    ...

#nothing added to commit but untracked files present (use "git add" to track)

5.2.3 添加 existing files to version control

  1. 首先 double check 你有一个 .gitignore file.

    shell
    head .gitignore
# This is a sample .gitignore file that's useful for C++ projects.

  2. 然后添加包括你的 .gitignore 在内的所有文件到 git 中，然后查看 status 就能看到很多待 commit 的 changded files.

    shell
    git add .
git status
#On branch main
#
#Changes to be committed:
#
#	new file:   .gitignore
    ...

  3. Commit 这些文件到 local repo with the commit message “Initial commit”.

    shell
    git commit -m "Initial commit"
#[main (root-commit) cefd222] Initial commit
# 1 file changed, 71 insertions(+)
# create mode 100644 .gitignore

  4. 可以 view commit log and see our first commit.

    shell
    git log
#commit cefd2227510fa5e16e357198be19832b952d314e (HEAD -> main)
#Author: Andrew DeOrio <awdeorio@umich.edu>
#Date:   Tue Aug 30 19:29:52 2022 -0400

#    Initial commit

  5. 然后可以看到the status is clean, 没有什么要 commit 的了.

    shell
    git status
# On branch main
# nothing to commit, working tree clean

  6. 你可能不想commit automatically generated or binary files. 因为这些些 Binaries 在别人的 machine 上不一定工作.

    shell
    git ls-files
...
# main.exe
# main.exe.dSYM/Contents/Info.plist
# main.exe.dSYM/Contents/Resources/DWARF/main.exe
...

    所以可以把他们从 git 中移除掉，不 commit.

    shell
    git rm -f main.exe
git rm -rf main.exe.dSYM
git status
# On branch main
# Changes to be committed:
#  (use "git restore --staged <file>..." to unstage)
#	deleted:    main.exe
#	deleted:    # main.exe.dSYM/Contents/Info.plist
#	deleted:    # main.exe.dSYM/Contents/Resources/DWARF/main.exe
git commit -m "remove binary files"
git status
# On branch main
# nothing to commit, working tree clean

5.3 创建 remote repo 及 connect local reop to remote

创建 remote repo 就是公公又式式的 github 页面上操作一下.

而如何 connect local repo 到 remote:

  1. 首先确定你在你有 git 的 directory.

    shell
    pwd
# github.com/awdeorio/p2-cv

  2. 使用这个 address 创建一个 origin

    这里非常重要的是，这个 origin 对于使用 SSH 和 Personal Token 的人是不一样的！

    For SSH:

    shell
    git remote add origin git@github.com:awdeorio/p2-cv.git  # use your URL

    For personal Token:

    shell
    git remote add origin https://github.com/awdeorio/p2-cv.git  # use your URL

    如果写错了那就删除 origin 然后重新写一遍.

    shell
    git remote rm origin

  3. 确认一下已经 connect 上 remote 了

    shell
    git remote -v
# origin	git@github.com:awdeorio/p2-cv.git (fetch)
# origin	git@github.com:awdeorio/p2-cv.git (push)

  4. Your local git may use master as the name for the initial branch, whereas GitHub expects it to be named main. 因而用 -M 指令改名

    shell
    git branch
# master
git branch -M main
git branch
# main

  5. 把已经 committed 到 local repo 的 commits push 到 remote repo.

    shell
    git push -u origin main

  6. 确认已经 commit, 并 verify commit log.

    shell
    $ git status
# On branch main
# Your branch is up to date with 'origin/main'.

# nothing to commit, working tree clean
git log
# commit cefd2227510fa5e16e357198be19832b952d314e (HEAD -> main)
# Author: Andrew DeOrio <awdeorio@umich.edu>
# Date:   Tue Aug 30 19:29:52 2022 -0400

#    Initial commit

5.4 Daily work flow with version control

  1. 查看 status，检查本地的 branch 是否已经同步更新了 server 的 change，以及本地的 change 是否已经 commit 和 push 到 server.

    shell
    git status

  2. Retrieve any changes from the server.

    shell
    git fetch
git rebase

  3. Make changes to files.

    shell
    git add SOME_FILE
git commit -m "Short description goes here"

  4. Push changes to GitHub server.

    shell
    git push

5.5 Version Control For a Team

5.5.1 添加 Collaborator

image-20240128013858402

而后：

  1. GitHub sends a confirmation email to your partner. Your partner clicks accept.

  2. Your partner creates an SSH key or a GitHub Personal Access Token.

  3. Your partner clone the remote repo on their own local machine using the same remote URL that you do.

    shell
    git clone https://github.com/awdeorio/p2-cv.git

5.5.2 解决 Conflict

The following text is copied from a helpful GitHub article.

When you perform a git rebase operation, you’re typically moving commits around. Because of this, you might get into a situation where a merge conflict is introduced. That means that two of your commits modified the same line in the same file, and Git doesn’t know which change to apply.

简单来说就是 merge conflict 发生了. 因为你们都 commit 了，但是你还没有 fetch 对方的 commit 就 commit 了.

这个时候你应该选择 merge 一个 branch. 可以直接在 Github Desktop 进行操作.

shell
git merge BRANCH-NAME

5.5.3 rejected pushes

如果你使用 git push 时 push 被 rejected error 了，那就是你的 teammate made 了一个 commit.

这个时候很简单，先 fetch 再 push.

5.6 注意事项

5.6.1 添加 commit 时的文字备注

比如：

shell
git commit -m "Added README"
git status

commit 一个 change 时应备注来表示做了什么.

5.6.2 README.md 文件

应该在 repo 中添加一个 README.md 文件来写这个 repo 的 instructions and descriptions.

shell
touch README.md
git add README.md
git commit -m "Added README"
git status

5.6.3 看 commit 的内容

shell
git diff 1.cpp

你可以通过 diff 命令查看 the last clean committed version of the file.

5.6.4 删库

首先在 Github 里面删除 repository.

然后删除 .git 这个 hidden file 以及 .gitignore.

shell
pwd
# /Users/awdeorio/Developer/eecs280/p2-cv
rm -rf .git/ .gitignore
ls -A
git status
# fatal: Not a git repository (or any of the parent directories): .git
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