Git & GitHub #

While Git is a local version control system, GitHub is a cloud-based platform for hosting Git repositories.

Files & Folders #

• README.md

• .gitignore

• .gitattributes

• .git/hooks

• .github/workflows/*.yml

Git Command Lines #

• git version

• git config list --show-origin

  Lists system, global, and local configurations and their origin.

• git config --global user.name <name>

• git config --global user.email <email>

• git clone <url>

---

• git init

• git status

• git stash

  Cuts the changes in the current project and pastes them into the stash archive.

  • git stash push <file-name>

    Cuts the changes in the specified file and pastes them into the stash archive.

  • git stash list

    Lists stashes.

  • git stash show

    Shows the changes in the latest stash.

  • git stash pop

    Cuts the latest stash in the stash archive and pastes it into the current project.

  • git stash apply

    Copies the latest stash in the stash archive into the current project.

  • git stash drop

    Deletes the latest stash in the stash archive.

• git add .

  Stages changes.

• git commit

  Creates a commit with staged changes.

  One task per commit. Avoid combining multiple tasks into a single commit.

  git commit --message (-m) <summary> --message (-m) <description>

  In IDEs, a blank line is required between the summary and the description.

  TextCopy

  <type>(optional scope): <summary>
  
  <description>

  <type> can be feat, fix, refactor, chore, style, docs, test, build, etc.

  <summary> should use the imperative mood, start with a lowercase letter, and end without a period.

  • git commit --amend

    Adds staged changes to the latest commit and updates its message.

• git revert <commit-id>

  Creates a commit that undoes the changes of the specified commit.

• git reset <commit-id>

  Deletes commits after the specified commit, keeps the changes unstaged, and preserves the specified commit. This has the implicit --mixed flag, which is the default.

  • git reset --soft <commit-id>

    Deletes commits after the specified commit, keeps the changes staged, and preserves the specified commit.

  • git reset --hard <commit-id>

    Deletes commits after the specified commit, also deletes the changes, and preserves the specified commit.

• git log

  Lists the commit history.

  • git log -S <string>

    Finds commits where the specified string was added or removed.

• git show

  Shows the latest commit with its diff.

---

• git branch

  Lists local branches.

  • git branch --verbose (-v)

    Lists local branches verbosely.

  • git branch --verbose --verbose (-vv)

    Lists local branches more verbosely.

  • git branch --all (-a)

    Lists local branches and remote repository branches.

  • git branch <branch-name>

    Creates the specified branch.

  • git branch --delete (-d) <branch-name>

    Deletes the specified branch.

  • git branch --move (-m) <specified-branch-name> <new-branch-name>

    Renames the specified branch.

• git checkout

  Shows a brief status of the current branch.

  • git checkout <branch-name>, git switch <branch-name>

    Moves from the current branch to the specified branch.

    Uncommited changes are carried over to the specified branch if there is no conflict.

  • git checkout -, git switch -

    Moves to the previous branch or commit.

  • git checkout -b <branch-name>, git switch --create (-c) <branch-name>

    Creates the specified branch and moves to it.

  • git checkout <commit-id>, git switch --detach <commit-id>

    Moves HEAD directly to the specified commit without being attached to any branch.

  • git checkout -- <file-name>, git restore <file-name>

    Restores the specified file to the last commit state.

• git merge <branch-name>

  Merges the specified branch into the current branch.

  • git merge --abort

  • git merge --continue

• git rebase <branch-name>

  Cuts the commits of the current branch that diverge from the specified branch and pastes them onto the specified branch to create a linear history. After rebasing, the specified branch should be fast-forward merged.

  • git rebase --interactive (-i) HEAD~<number>

    Goes back to the specified number of commits and modifies them interactively (pick, edit, squash, fixup, reword, drop, etc.).

  • git rebase --abort

  • git rebase --continue

---

• git remote

  Lists remote repository aliases.

• git remote --verbose (-v)

  Lists remote repository aliases and their URLs.

• git remote add <remote-repository-alias> <remote-repository-url>

  Creates the alias for the remote repository and connects the current project to it.

• git remote remove (rm) <remote-repository-alias>

  Disconnects the current project from the specified remote repository.

• git remote set-url <remote-repository-alias> <remote-repository-url>

  Updates the URL of the specified remote repository.

• git push <remote-repository-alias> <branch-name>

  Uploads the local branch to the remote repository branch that has the same name as the local branch. If the local and remote names are different, <branch-name> will be <local-branch-name>:<remote-repository-branch-name>

  • git push --set-upstream (-u) <remote-repository-alias> <branch-name>

    Uploads and remembers this connection. Thereafter, you can simply run git push, git fetch, or git pull without arguments.

• git fetch <remote-repository-alias> <remote-branch-name>

  Downloads the changes from the specified remote repository branch without merging them.

• git pull <remote-repository-alias> <remote-branch-name>

  Downloads the changes from the specified remote repository branch and merges them into the current branch.

Git Hooks #

Git Hooks are located in .git/hooks and must not have a file extension.

Git Hooks are custom scripts that trigger actions whenever a specified event occurs. They are divided into client-side hooks and server-side hooks.

commit-msg is a client-side hook that runs right after the commit message is created, allowing for its validation.
The following code creates a custom modal box that checks if the commit message contains content.

#!/bin/sh
COMMIT_MSG=$(cat "$1")
if echo "$COMMIT_MSG" | grep -iq "content"; then
    USER_CHOICE=$(powershell.exe -Command "
        [System.Reflection.Assembly]::LoadWithPartialName('System.Windows.Forms') | Out-Null;
        [System.Reflection.Assembly]::LoadWithPartialName('System.Drawing') | Out-Null;

        # Play default notification sound (Asterisk) when the window appears
        [System.Media.SystemSounds]::Asterisk.Play();

        # 1. Create the main window form
        \$form = New-Object System.Windows.Forms.Form;
        \$form.Text = '⚠️ Git Hook commit-msg';
        \$form.Size = New-Object System.Drawing.Size(550, 260);
        \$form.StartPosition = 'CenterScreen';
        \$form.FormBorderStyle = 'FixedDialog';
        \$form.MaximizeBox = \$false;
        \$form.MinimizeBox = \$false;
        \$form.TopMost = \$true;

        # 2. Create the message text label
        \$label = New-Object System.Windows.Forms.Label;
        \$label.Text = \"The 'content' type has been detected!

Did you update the 'lastUpdated' variable?\";
        \$label.Location = New-Object System.Drawing.Point(30, 30);
        \$label.Size = New-Object System.Drawing.Size(490, 100);
        \$label.Font = New-Object System.Drawing.Font('Malgun Gothic', 14, [System.Drawing.FontStyle]::Bold); 

        # 3. Create the [Yes] button (No click sound)
        \$btnYes = New-Object System.Windows.Forms.Button;
        \$btnYes.Text = 'Yes';
        \$btnYes.DialogResult = [System.Windows.Forms.DialogResult]::Yes;
        \$btnYes.Location = New-Object System.Drawing.Point(140, 150);
        \$btnYes.Size = New-Object System.Drawing.Size(120, 45);
        \$btnYes.Font = New-Object System.Drawing.Font('Malgun Gothic', 11);

        # 4. Create the [No] button
        \$btnNo = New-Object System.Windows.Forms.Button;
        \$btnNo.Text = 'No';
        \$btnNo.DialogResult = [System.Windows.Forms.DialogResult]::No;
        \$btnNo.Location = New-Object System.Drawing.Point(280, 150);
        \$btnNo.Size = New-Object System.Drawing.Size(120, 45);
        \$btnNo.Font = New-Object System.Drawing.Font('Malgun Gothic', 11);
        # Play heavy error sound (Hand) when [No] is clicked
        \$btnNo.Add_Click({ [System.Media.SystemSounds]::Hand.Play() });

        # 5. Add components to the window form
        \$form.Controls.Add(\$label);
        \$form.Controls.Add(\$btnYes);
        \$form.Controls.Add(\$btnNo);

        # 6. Open the window and output the user click result
        \$result = \$form.ShowDialog();
        Write-Output \$result;
    " | tr -d '\r')

    if [ "$USER_CHOICE" = "No" ] || [ -z "$USER_CHOICE" ]; then
        echo "❌ The commit was canceled. Please update the 'lastUpdated' variable."
        exit 1
    fi
fi
exit 0

GitHub Actions is a continuous integration and continuous deployment (CI/CD) service.

GitHub Actions provides secrets, variables, artifacts, and outputs.

GitHub Actions consists of workflows that are located in .github/workflows with .yml. Workflows are triggered by specific events and contain one or more jobs.

Jobs run on a runner and contain one or more steps. Jobs run in parallel by default but can run sequentially by specifying needs.

Steps execute a shell command, a custom action, or a third-party action. Steps run in order.

Troubleshooting #

Korean comments are garbled in GitHub.

The connection between a local repository and GitHub is lost.