1. ติดตั้ง Git
2. Getting a Git Repository
3. Recording Changes to the Repository
4. Branch
5. Tag
6. Fix

1. ติดตั้ง Git

• How To Install Git on CentOS 7
• 1.5 Getting Started – Installing Git

Install Git with Yum

sudo yum install git

Install Git with apt

sudo apt install git

ตรวจสอบการติดตั้ง

git --version

Set Up Git

• Git – Git Configuration (git-scm.com)

Name and email address

git config --global user.name "Your Name"
git config --global user.email "you@example.com"

Git can handle this by auto-converting CRLF line endings into LF when you add a file to the index, and vice versa when it checks out code onto your filesystem. You can turn on this functionality with the core.autocrlf setting. If you’re on a Windows machine, set it to true — this converts LF endings into CRLF when you check out code:

Formatting

git config --global core.autocrlf true

If you’re on a Linux or macOS system that uses LF line endings, then you don’t want Git to automatically convert them when you check out files; however, if a file with CRLF endings accidentally gets introduced, then you may want Git to fix it. You can tell Git to convert CRLF to LF on commit but not the other way around by setting core.autocrlf to input:

git config --global core.autocrlf input

Your default branch name

By default Git will create a branch called master when you create a new repository with git init. From Git version 2.28 onwards, you can set a different name for the initial branch.

git config --global init.defaultBranch main

Ignorecase

• Git – git-config Documentation (git-scm.com)

git config --global core.ignorecase false

Checking Your Settings

ค่าที่แสดงออกมา มีทั้งค่า global และ user

git config --list

You can view all of your settings and where they are coming from using:

ดูว่า config อะไรมาจากไฟล์ไหนใช้ --show-origin

git config --list --show-origin

Git config file locations

• Where system, global and local Git config files on Windows and Ubuntu Linux are (theserverside.com)

2. Getting a Git Repository

Initializing a Repository in an Existing Directory

cd /home/user/my_project
git init

git add *.c
git add LICENSE
git commit -m 'Initial project version'

หรือ add ทุกไฟล์ใน directory ด้วย

git add .

แต่ถ้าจะลบไฟล์ก็ git rm (ลบไฟล์พร้อมกับ stage ให้ด้วย)

git rm <filename>

แต่ถ้าจะ discard (Undoing Uncommitted Changes) – Git Undo Commit: How to Undo Changes in Git (cloudbees.com)

$ git stash

Cloning an Existing Repository

You clone a repository with git clone <url>. For example, if you want to clone the Git linkable library called libgit2, you can do so like this:

git clone https://github.com/libgit2/libgit2

If you want to clone the repository into a directory named something other than libgit2, you can specify the new directory name as an additional argument:

git clone https://github.com/libgit2/libgit2 mylibgit

ถ้า clone แล้วได้ error

fatal: unable to access 'https://gitxxx.com/jack/jack.git/': Peer's Certificate issuer is not recognized.

ให้แก้ไขโดยการ ignore CA – git – what does this error message imply: fatal: unable to access ‘https:URL’: Peer’s Certificate issuer is not recognized? – Stack Overflow

env GIT_SSL_NO_VERIFY=true git clone https://github...

หรือ set http.sslverify ให้เป็น false เลย

$ git config --global http.sslverify false

3. Recording Changes to the Repository

• 2.2 Git Basics – Recording Changes to the Repository

Checking the Status of Your Files

git status

ถ้าจะให้แสดง diff (staged) ด้วยก็

git status -v

หรือถ้าจะดูสรุปสั้นๆก็

git status -s

$ echo 'My Project' > README
$ git status
On branch master
Your branch is up-to-date with 'origin/master'.
Untracked files:
  (use "git add <file>..." to include in what will be committed)

    README

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

Tracking New Files

git add README

$ git status
On branch master
Your branch is up-to-date with 'origin/master'.
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)

    new file:   README

Ignoring Files

$ cat .gitignore
*.[oa]
*~

Viewing Your Staged and Unstaged Changes

To see what you’ve changed but not yet staged, type git diff with no other arguments:

git diff

If you want to see what you’ve staged that will go into your next commit, you can use git diff --staged or git diff --cached.

git diff --staged

หรือ

git status -v

Committing Your Changes

git commit -m "Story 182: fix benchmarks for speed"

ดูประวัติการ commit

git log
git log --oneline
git log --oneline --graph

การ reset (ย้อนกลับ) โดย default จะเป็นแบบ mixed

git reset <เลข commit ที่ได้จาก git log>

ดูประวัติ commit (รวมที่ reset ไปแล้วด้วย)

git reflog

ถ้าอยากย้อนกลับไป commit ที่เคย reset หายไปแล้ว ก็ทำได้ด้วย

git reset <เลข commit ที่ได้จาก git reflog>

git push

• Git – git-push Documentation (git-scm.com)

git push origin main

git pull

• Git – git-pull Documentation (git-scm.com)

git pull

git fetch

• Git – git-fetch Documentation (git-scm.com)

git fetch

4. Branch

• A successful Git branching model » nvie.com

Create Branch

git branch <branch_name>

Remove Branch (Local)

git branch -d <branch_name>

Switch Branch

git checkout <branch_name>

Create and Switch Branch

git checkout -b <branch_name> <commit_id (optional)>

List branch

git branch

Git Merge

git merge <branch_name>
git merge <branch_name> --no-ff # merge commit

5. Tag

• Git – Tagging (git-scm.com)

Listing Your Tags

Listing the existing tags in Git is straightforward. Just type git tag (with optional -l or --list):

$ git tag
v1.0
v2.0

This command lists the tags in alphabetical order; the order in which they are displayed has no real importance.

You can also search for tags that match a particular pattern. The Git source repo, for instance, contains more than 500 tags. If you’re interested only in looking at the 1.8.5 series, you can run this:

$ git tag -l "v1.8.5*"
v1.8.5
v1.8.5-rc0
v1.8.5-rc1
v1.8.5-rc2
v1.8.5-rc3
v1.8.5.1
v1.8.5.2
v1.8.5.3
v1.8.5.4
v1.8.5.5

Creating Tags

Git supports two types of tags: lightweight and annotated.

A lightweight tag is very much like a branch that doesn’t change — it’s just a pointer to a specific commit.

Annotated tags, however, are stored as full objects in the Git database. They’re checksummed; contain the tagger name, email, and date; have a tagging message; and can be signed and verified with GNU Privacy Guard (GPG). It’s generally recommended that you create annotated tags so you can have all this information; but if you want a temporary tag or for some reason don’t want to keep the other information, lightweight tags are available too.

Annotated Tags

Creating an annotated tag in Git is simple. The easiest way is to specify -a when you run the tag command:

$ git tag -a v1.4 -m "my version 1.4"
$ git tag
v0.1
v1.3
v1.4

You can see the tag data along with the commit that was tagged by using the git show command:

$ git show v1.4
tag v1.4
Tagger: Ben Straub <ben@straub.cc>
Date:   Sat May 3 20:19:12 2014 -0700

my version 1.4

commit ca82a6dff817ec66f44342007202690a93763949
Author: Scott Chacon <schacon@gee-mail.com>
Date:   Mon Mar 17 21:52:11 2008 -0700

    Change version number

Push a tag to a remote repository

• How do you push a tag to a remote repository using Git? – Stack Overflow

To push a single tag:

git push origin <tag_name>

And the following command should push all tags (not recommended):

# not recommended
git push --tags

6. Fix

ยังไม่ได้เชื่อมต่อด้วย SSH

• Use SSH keys to communicate with GitLab | GitLab

ดูที่ Generate an SSH key pair

SSL certificate problem: unable to get local issuer certificate

• SSL certificate problem: Unable to get local issuer certificate | Bitbucket Data Center and Server | Atlassian Documentation

Resolution #1 – Self Signed certificate

Tell git to not perform the validation of the certificate using the global option:

git config --global http.sslVerify false

You must use a personal access token with ‘read_repository’ or ‘write_repository’ scope for Git over HTTP.

วิธีแก้

สร้าง personal access token ที่มีสิทธิ read_repository or write_repository เป็นอย่างน้อย

สั่งรัน git clone ใหม่ แล้วจะมีไดอะล็อก ให้ใส่ username, password ก็ใส่ตามนี้

username: login
password: <credential ที่ได้จากตอนสร้าง personal access token>

แต่ถ้าไม่มีไดอะล็อก ให้ลองไปลบ ของเดิมที่ Credential Manager

• How to start using a personal access token to authenticate git on windows – GitHub Help / How to use Git and GitHub – GitHub Community

ถ้ารันคำสั่ง git เช่น git fetch แล้วถาม password ทุกครั้ง ให้ set ตามนี้เพื่อจำ password (Make Git store the username and password and it will never ask for them.) – How to fix Git always asking for user credentials (freecodecamp.org)

git config --global credential.helper store