git/github basic usage guide

Git/Github Usage and Instruction

note:

• make sure that target local files are located in repository folder.

• Cannot operate files outside repository folder.

• two file transferring paths: http and SSH( Recommaded, openssh required)

• *set authentication(鉴权).

  • In .git/config, add username and passwd after url

config git

• totally new env
  create ssh key

  ssh-keygen -t rsa -C "your_email@youremail.com"  

• set user info

  git config --global user.name "your name"  
  git config --global user.email "your_email@youremail.com"

• check user

  git config user.name  
  git config user.email

• check all information

  git config -l

repository initializatioin

相关操作，在 GitHub 创建新 repository 时，会出现提醒，内容如下：

create a new repository on the command line

echo "# README" >> README.md
git init
git add README.md
git commit -m "first commit"
git branch -M main
git remote add origin <git url>
git push -u origin main

push an existing repository from the command line

git remote add origin <git url>
git branch -M main
git push -u origin main

repository operation

local repository trilayer structure

• add files to index(cache space)

  git add file1 file2 ...  

• add version annatation

  git commit -m "modification_annotation"

• view current git status

  git status

• push modification to remote repository

  git push origin master

• pull latest version from repostory

  git pull

about version

• get version list (not incluede the versions hereafter)

  git log [ --pretty=online ]

• set current version

  git reset --hard version_number

• get all versions

  git reflog

branch command

branch pattern

• list branch

  git branch

• create branch

  git branch name

• switch branch

  git checkout name

• creat and switch branch

  git checkout -b name

• delete

  git branch -d name

• merge

  git merge names

Note: the operations in different branches do not influence each other. Merge operation is in need af final.

solve conflicts

add git sshkey into Github

• create a SSH key

  ssh-keygen -t rsa -C "your_email@example.com"

  default generated file ~/.ssh/id_rsa.pub

• add SSH key content into github SSH
  setting -> SSH and GPG keys

日常遇到的问题

Offending RSA key in ~/.ssh/known_hosts:2

在进行 git push/pull 的时候，发生如下错误：

$ ssh -T git@github.com
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
SHA256:uNVztksCshcc0ueBujQXVUpZIDTMczCvjtD2.
Please contact your system administrator.
Add correct host key in ~/.ssh/known_hosts to get rid of this message.
Offending RSA key in ~/.ssh/known_hosts:2
RSA host key for github.com has changed and you have requested strict checking.
Host key verification failed.

多番查阅后，总结是 GitHub rsa-id 更新，使用 ecdsa 方式。
所以，一方面要删除 ~/.ssh/known_host 中的 rsa:

• 可以根据错误提示 Offending RSA key in ~/.ssh/known_hosts:2，进入 known_host 进行手动删除，也可以命令行的方式进行删除（在你知道 host IP 的前提下）

  ssh-keygen -t rsa -R github.com

在此之后，更新 GitHub 账户上的 host-key:

• 将 ~/.ssh/known_hosts 中信息添加到 Settings -> SSH and GPG keys -> New SSH key