Git

Everything about Git

git
git

Git Pro

复现commit id

How does Git create unique commit hashes, mainly the first few characters?

Git uses the following information to generate the sha-1:

  • The source tree of the commit (which unravels to all the subtrees and blobs)
  • The parent commit sha1
  • The author info (with timestamp)
  • The committer info (right, those are different!, also with timestamp)
  • The commit message

完整说明，另外可参考The anatomy of a Git commit，和 10.1 Git 内部原理 - 底层命令与上层命令对应的英文版本——10.1 Git Internals - Plumbing and Porcelain

执行以下步骤可以复现commit id——

  • git show 获得当前最新的commit信息
  • git cat-file commit HEAD
  • printf "commit %s\0" $(git cat-file commit HEAD | wc -c) 在开头增加commit len\0 文本，长度，NUL-terminated header
  • (printf "commit %s\0" $(git cat-file commit HEAD | wc -c); git cat-file commit HEAD) | sha1sum组合上面两步的内容作为SHA1算法的输入，计算获得的40个字符长度文本就是commitid信息——复现成功

第二步的结构化信息——

sha1(
    tree            => 9c435a86e664be00db0d973e981425e4a3ef3f8d （对所有tree对象的递归计算到root节点）
    parents         => [0d973e9c4353ef3f8ddb98a86e664be001425e4a]
    author(with timestamp)          => Christoph Burgdorf <christoph.burgdorf@gmail.com> Sat Nov 8 11:13:49 2014 +0100
    committer(with timestamp)        => Christoph Burgdorf <christoph.burgdorf@gmail.com> Sat Nov 8 11:13:49 2014 +0100
    commit message  => "second commit"
)

理解Git中的对象概念：Tree Object（对目录、或目录和文件的SHA-1描述。如何获取的？）

.
├── .git (contents left out)
├── assets
|   ├── logo.png
|   └── app.css
└── app.js

git tree object

键值数据库文件系统；使用zlib进行压缩存储对象；SHA1摘要算法

Every object consists of three things - a type, a size and content. The size is simply the size of the contents, the contents depend on what type of object it is, and there are four different types of objects: “blob”, “tree”, “commit”, and “tag”.

git write-tree Create a tree object from the current index. returns the hash of the top level tree.

git ls-tree List the contents of a tree object. 可以使用 git cat-file -p treehash起到同样的作用

git cat-file Provide content or type and size information for repository objects

joechin@Gebitang MINGW64 /e/0daywork/gitinit (master)
$ git status
On branch master

No commits yet

Changes to be committed:
  (use "git rm --cached <file>..." to unstage)

        new file:   h.txt
        new file:   lib/lealone.png


joechin@Gebitang MINGW64 /e/0daywork/gitinit (master)
$ git write-tree
f6da736647be31514378f51704936fcf40171a07

joechin@Gebitang MINGW64 /e/0daywork/gitinit (master)
$ git ls-tree f6da73
100644 blob ce013625030ba8dba906f756967f9e9ca394464a    h.txt
040000 tree 5de66da52a71d943871ac3753fbed006ee0688f4    lib

joechin@Gebitang MINGW64 /e/0daywork/gitinit (master)
$ git cat-file tree f6da736647be31514378f51704936fcf40171a07
100644 h.txt▒6%
               ▒۩▒V▒▒▒▒▒FJ40000 lib]▒m▒*q▒C▒▒u?▒▒▒▒▒

Git命令使用

可配合GUI工具和命令行工具参考。

Filename too long in Git for Windows

Filename too long in Git for Windows

使用管理员权限执行git config --system core.longpaths true修复此问题。

error: could not lock config file C:/Program Files/Git/mingw64/etc/gitconfig: Permission denied

git clone sonarqube源码时，提示

Resolving deltas: 100% (498459/498459), done. fatal: cannot create directory at ‘server/sonar-db-migration/src/test/resources/org/sonar/server/platform/db/migration/version/v84/permissiontemplates/fk/permtplcharacteristics/AddUniqueIndexOnTemplateUuidAndPermissionKeyColumnsOfPermTplCharacteristicsTableTest’: Filename too long warning: Clone succeeded, but checkout failed. You can inspect what was checked out with ‘git status’ and retry the checkout with ‘git checkout -f HEAD’

然后再执行git checkout -f HEAD。今天我守着不完整的代码找半天webhook相关的内容

git http clone方式报错：

error: RPC failed; curl transfer closed with outstanding read data remaining

  • $ git clone http://github.com/large-repository --depth 1
  • cd large-repository
  • git fetch --unshallow

git clone with token in command line

work for gitlab at list:

git clone https://oauth2:ACCESS_TOKEN@somegitlab.com/vendor/package.git

change remote url

git remote -v
# View existing remotes

git remote set-url origin https://github.com/user/repo2.git
# Change the 'origin' remote's URL

git remote -v
# Verify new remote URL

use token from command line

use token from command line

$ git clone https://github.com/username/repo.git
Username: your_username
Password: your_token

fatal: Unable to create ‘/path/my_project/.git/index.lock’: File exists

sto: rm -f ./.git/index.lock

修改commit工具 vim

提交说明信息的时候, linux默认是 nano 编辑器
nano 这个编辑器使用 ctrl + x 来退出

# global
git config --global core.editor vim

# project update: .git/config add--
editor=vim

查找rep中特定用户的提交记录

official doc, from Stackoverflow

git log --since=2018-01-01  --pretty=oneline --author=uername --author=gebitang |wc -l

ssh variant ‘simple’ does not support setting port

update setting for git： git config --global ssh.variant ssh

Git Bash: Could not open a connection to your authentication agent

生成公钥添加到对应的网站后，直接clone时，可能提示无法验证。

# need to start ssh-agent first.
eval `ssh-agent -s`

Permission denied (publickey).

添加公钥之后，测试验证时会提示“Permission denied (publickey).”。这是因为还没有将生成的对应的key添加到ssh管理中（默认生成的会自动添加，后续生成的多个rsa文件需要手动添加）

# step 1 start agent first.  "ssh-agent bash" or " eval `ssh-agent` "

joechin@Gebitang MINGW64 ~/.ssh
$ ssh-agent bash


joechin@Gebitang MINGW64 ~/.ssh
$ ssh-add xxx_id_rsa
Identity added: xxx_id_rsa (aaaa@xxx.com)


# add the_abs_path_of_the_new_RSA_file, such as ~/.ssh/coding_id_rsa
ssh-add coding_id_rsa

# " Could not open a connection to your authentication agent" show, go to step 1

# then it could be cloned normaly.

Fork and Sync Repo

1. git remote add upstream  https://github.com/url/project.git
2. git fetch upstream //download objects and refs from another repository 
3. git merge upstream/master //merge upstream/master to current branch

#meaning of merge
git merge origin master //将origin merge 到 master 上
git merge origin/master //将origin上的master分支 merge 到当前 branch 上 

$ git remote add upstream  https://github.com/b3log/pipe.git

#查看添加结果
$ git remote -v
origin  git@github.com:gebitang/pipe.git (fetch)
origin  git@github.com:gebitang/pipe.git (push)
upstream        https://github.com/b3log/pipe.git (fetch)
upstream        https://github.com/b3log/pipe.git (push)


$ git fetch upstream

$ git merge upstream/master

指定branch clone

git clone -b dawn-2.x git@github.com:EOSIO/eos.git

git checkout

test@test~$git checkout -b upcoming origin/upcoming
正在检出文件: 100% (1718/1718), 完成.
分支 'upcoming' 设置为跟踪来自 'origin' 的远程分支 'upcoming'。
切换到一个新分支 'upcoming'
test@test~$

0x0. 命令行单独对不同的文件进行commit操作

#理解暂存区的概念，多个文件即可分别处理
git add new.file/modified.file
#然后进行commit，即完成分别进行commit的动作
git commit 

#-a参数对所有工作区的文件都有效，未添加到跟踪区的文件除外
git commit -a

0x1. 配置github账号

注意事项：source

  1. 生成rsa文件时可以指定不同的名称，以保证可以生成使用多个
  2. 需要输入passphrase，否则系统认定不够安全，不允许添加到ssh-agent中
  3. 配置config 文件，支持多个git账号
  4. 如果不进行config的配置，在添加ssh key之后，将统一使用global的设置

ssh config 示例 多个rsa文件时

SSH CONFIG FILE OpenSSH Config File Examples

配置了多个公钥后，需要针对不同的站点进行配置，否则会在git clone等交互操作时依然提示需要输入秘密。

配置了config文件后，idea中会根据这个配置文件使用对应的keyUsing Git integration

提交commit时，依然需要至少有user.name和user.email信息

# 对于ssh的配置
# Defines for which host or hosts the configuration section applies. 
# The section ends with a new Host section or the end of the file. 
# A single * as a pattern can be used to provide global defaults for all hosts.
Host github.com
    # Specifies the real host name to log into. Numeric IP addresses are also permitted.
    HostName github.com
    # Defines the username for the SSH connection.
    User gebitang
    # Specifies a file from which the user’s DSA, ECDSA or DSA authentication identity is read. 
    IdentityFile ~/.ssh/id_rsa
Host prj.testin.cn
    HostName prj.testin.cn
    # Specifies the port number to connect on the remote host.
    Port 8201
    # The default is ~/.ssh/identity for protocol version 1, and ~/.ssh/id_dsa, ~/.ssh/id_ecdsa and ~/.ssh/id_rsa for protocol version 2.
    IdentityFile ~/.ssh/gitlab_id_rsa
Host git.coding.net
    HostName git.coding.net
    IdentityFile ~/.ssh/coding_id_rsa
Host bitbucket
    HostName bitbucket.org
    IdentityFile ~/.ssh/bitbucket_id_rsa
  • ssh配置

生成ssh-key

ssh-keygen -t rsa -b 4096 -C "email@address.com"

添加ssh key（id_rsa_xxx、id_rsa_xxx.pub）到对应的repository，如github、gitlab，即可保证可以从对应的设备上就可以访问对应的repository。

  • git配置

git config 配置完全局的 --global user.name 和 --global user.email之后，可以在对应的仓库下，配置当前仓库使用的user.name 和user.email

0x2. commit amend修改commit

使用 git commit –amend 参数可以对最近的提交进行修改。 作用相当于新提交了一个commit。 如果修改前的commit已经被同步过，需要先进行拉取 git pull的操作 否则在推送amend之后的commit时会提示:

$ git push origin master
To git@github.com:gebitang/gebitang.com.git
 ! [rejected]        master -> master (non-fast-forward)
error: failed to push some refs to 'git@github.com:gebitang/gebitang.com.git'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Integrate the remote changes (e.g.
hint: 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

0x3. Permission denied (publickey)问题

原因：SSH的配置文件ssh_config中的“IdentityFile“ 与实际情况不相符 生成的一对秘钥，公钥上传到对应的站点后，使用-vt参数进行调试验证

#测试连接情况
# v for verbose mode, V for version
ssh -vT git@git.coding.net

如果clone时使用了https格式，则再次推送时总是会提示输入用户名密码，可以通过git config --list查看，然后修改remote.origin.url的值

0x4. 合并commits

参考

# -i for interactive, 而不是指 其中，-i 的参数是不需要合并的 commit 的 hash 值 
# commitid 可理解为在此commit上进行rebase。即此commit之后的commit都可以进行rebase:)
git rebase -i commitid

原理：选择要rebase的基础commit，进入交互模式，根据提示对不同的commit处理为pick或squash

0x5. 清理、合并操作

Your local changes to the following files would be overwritten by merge

提示上述错误信息时，可以使用下面的命令清理

git clean -d -fx

注意：会导致工程的所有配置都会丢失

git merge branch.name

0x6. 重新添加已经忽略的文件

#添加已经忽略的文件 
git add -f ignored/file/name
#忽略已经添加的文件 
git rm --cached file/want/to/be/ignore

参考

git rm

删除文件

# 先本地删除
rm test.txt
# 在从git删除
git rm test.txt 
# 然后commit提交
git commit "delete test.txt file."
# 本地需要的话，可以更新到gitignore文件中

更新mac后默认自带的git无法使用

StackOverFlow

➜  gebitang.com git status
xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
➜  gebitang.com sudo xcodebuild -license
Password:
xcode-select: error: tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance
➜  gebitang.com sudo /usr/bin/git
xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
➜  gebitang.com xcode-select --install
xcode-select: note: install requested for command line developer tools
➜  gebitang.com
➜  gebitang.com git:(master) ✗
➜  gebitang.com git:(master) ✗

升级到Big Sur之后git无法使用

到git仓库下执行git status检查时提示找不到git，not a developer tool or in PATH。 搜索了一圈，只有这个比较靠谱

检查了一下/Applications/Xcode.app/Contents/Developer/usr/bin这个目录下有git，暂时将这个目录手动添加到环境变量后，问题解决。

sh: line 1:  3799 Bus error: 10           /Applications/Xcode.app/Contents/Developer/usr/bin/xcodebuild -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -find git 2> /dev/null
git: error: unable to find utility "git", not a developer tool or in PATH

git log历史

git log --oneline # show all logs line by line
git show commit # show the commit detail 

git log commit 　　# 查询commit之前的记录，包含commit
git log commit1 commit2  # 查询commit1与commit2之间的记录，包括commit1和commit2
git log commit1..commit2 # 同上，但是不包括commit1

项目初始化

  • create empty project
# from 0 to 1
mkdir gotourgo
cd gotourgo
git init
echo "# gotourgo" >> README.md
git add README.md
git commit -m "first commit"
git remote add origin git@git.coding.net:gebitang/gotourgo.git
git push -u origin master
  • add existed one
git remote add origin git@git.coding.net:gebitang/gotourgo.git
git push -u origin master

指定branch复制

git clone git@192.168.1.93:Automation/project.git -b next next

修改、忽略、撤销、删除、更新url

# 修改已提交的commit
git commit --amend
#忽略已跟踪的文件
git update-index --assume-unchanged filename
#撤销用：
git update-index --no-assume-unchanged filename
#删除已入仓库的文件夹
git rm -r --cached .idea/
git rm -r --cached 要忽略的文件

#git修改文件名大小写的方法。
#首先，在git命令行里面运行：
git config core.ignorecase false

#更新url
git remote set-url origin new-url

#rebase
git rebase -i base-commit-hash

Basic Command line instructions

Git global setup
git config --global user.name "gebitang"
git config --global user.email "gebitang@hotmail.com"

Create a new repository
git clone git@gitlab.com:gebitang/simpleweb.git
cd simpleweb
touch README.md
git add README.md
git commit -m "add README"
git push -u origin master

Existing folder
cd existing_folder
git init
git remote add origin git@gitlab.com:gebitang/simpleweb.git
git add .
git commit -m "Initial commit"
git push -u origin master

Existing Git repository
cd existing_repo
git remote rename origin old-origin
git remote add origin git@gitlab.com:gebitang/simpleweb.git
git push -u origin --all
git push -u origin --tags

显示分支branch的关系

STO

# branch A B C
git log --graph --decorate --oneline --simplify-by-decoration A B C
# all 
git log --graph --decorate --oneline --simplify-by-decoration --all

git tag

tag默认是按照字母顺序排列的。tag操作

# 查看所以tag  -l 注意是字母"L",以列表形式列出所有tag的版本号. -n 显示出每个版本号对应的附加说明.
git tag -l -n
# 显示时间
git log --tags --simplify-by-decoration --pretty="format:%ci %d "
# 一行显示
git log --tags --simplify-by-decoration --pretty="format:%ci %d "

git更新历史commit中的author信息

https://help.github.com/en/github/using-git/changing-author-info

https://www.git-tower.com/learn/git/faq/change-author-name-email

更新最近一次commit的committer：

git commit --amend --author="John Doe <john@doe.org>"

https://blog.tinned-software.net/rewrite-author-of-entire-git-repository/

Rewriting the history is done with “git filter-branch” by walking through the complete history. For each commit, filters are applied after which the changes are re-committed. The different filters allow modifying different parts of the commit.

The following uses “git filter-branch” to filter the history. Instead of manipulating the files to be recommitted like explained in Remove files from git history, this command uses the “–env-filter” to alter the environment in which the re-committing statement takes place.

单独clone出来当前repo

git clone --bare https://github.com/user/repo.git
cd repo.git

执行修改动作

#!/bin/sh
# -f to force rewrite, such as git filter-branch -f --env-filter
git filter-branch --env-filter '

OLD_EMAIL="your-old-email@example.com"
CORRECT_NAME="Your Correct Name"
CORRECT_EMAIL="your-correct-email@example.com"

if [ "$GIT_COMMITTER_EMAIL" = "$OLD_EMAIL" ]
then
    export GIT_COMMITTER_NAME="$CORRECT_NAME"
    export GIT_COMMITTER_EMAIL="$CORRECT_EMAIL"
fi
if [ "$GIT_AUTHOR_EMAIL" = "$OLD_EMAIL" ]
then
    export GIT_AUTHOR_NAME="$CORRECT_NAME"
    export GIT_AUTHOR_EMAIL="$CORRECT_EMAIL"
fi
' --tag-name-filter cat -- --branches --tags

这样修改后，会导致远端与本地所有替换的内容都认为不同，需要重新先 ‘git pull’ 获取一次，当出现’fatal: refusing to merge unrelated histories’的提示时，需要执行’git pull origin master –allow-unrelated-histories’命令，然后修改可能的冲突即可。

更新修改后的repo

git push --force --tags origin 'refs/heads/*'

最后可以删除临时的repo

 
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