[toc]

Git Note and Configurations

TO-DO

• Learn Atlassian Git tutorial from the ref link

Reference

• Git Reference - Git
• GitHub Git Cheat Sheet - GitHub
• Git Cheatsheet - NDP Software
• Pro Git Online Book- Git
• How to Set Up Git for the First Time on macOS - freeCodeCamp
• How to upgrade Git on Mac (OSX) - Ajahne GitHub IO
• Create Useful .gitignroe Files for Your Project - gitignore.io
• Git Ignore and .gitignore - W3Schools
• Git reset - Atlassian
• Git Tutorials - Atlassian
• Git rebase

Git in Homebrew

Install

1. To replace the built-in Git on macOS, install the Git from Homebrew:

   brew install git

2. Change the local path to the Homebrew version:

   export PATH=/usr/local/bin:$PATH

3. Check the current version:

   git --version

Update

1. Fetch the newest version of Homebrew and all formulae:

   brew update

2. Upgrade Git:

   brew upgrade git

Setups and Configurations

Global

Path: ~/.gitconfig

• Set up the global user name:

  git config --global user.name "username"

• Set up the global user email:

  git config --global user.email "[email protected]"

• Check the global configuration:

  git config --global --list

  git config --global --get <config_name>

Local

Path: repo_path/.git/config

• Set up the local user name:

  git config --local user.name "username"

• Set up the local user email:

  git config --local user.email "[email protected]"

• Check the local configuration:

  git config --local --list

  git config --local --get <config_name>

System

In Git, the system-level configuration refers to the configuration settings applied globally across all users on a system. These settings are stored in a system-wide configuration file and are typically shared among all users on a machine. The system configuration is the broadest level of Git configuration and affects all repositories on the system.

• Check the system configuration:

  git config --system --list

  git config --system --get <config_name>

File Statement

Untracked/Tracked

Files that are untracked or tracked by Git.

Modified

Files that have been changed but not staged yet.

Staged

Files that have been marked for the next commit.

Committed

Files that have been committed to the repository.

Stashed

Files that have been temporarily saved.

Usage:

• git stash [save <message>]: stash the current changes, and revert the current working directory to the state of the last commit.
• git stash list: show a list of stashes with their names and messages.
• git stash apply [<stash>]: apply the stash.
• git stash pop [<stash>]: apply and drop the stash.
• git stash drop [<stash>]: drop the stash.
• git stash clear: drop all stashes.

Ignored

Files that are intentionally ignored by using .gitignore.

Ignore Files

Local Repo

Shared w/ Collaborators

1. Create a .gitignore inside the repo.
2. Add the names/patterns of files/directories to be ignored.
3. Save the file and commit to the repo.

Git will not track files and folders specified in the .gitignore, but the .gitignore itself will be tracked. It can also be created inside a subdirectory to ignore files/folders within the directory.

Not Shared w/ Collaborators

1. Create a .git/info/exclude inside the repo.
2. Add the names/patterns of files/directories to be ignored.
3. Save the file and commit to the repo.

It works the same way as .gitignore but will not be shown to anyone else.

Global Settings

1. Enable core.excludesfile option in the global Git configuration:

   git config --global core.excludesfile ~/<.global_ignore_cfg>

2. Create the ~/<.global_ignore_cfg>.

3. Add the names/patterns of files/directories to be ignored.

4. Save the file.

The ~/<.global_ignore_cfg> rules will be applied to all Git repos.

Git Undo

Revert

revert will take a previous commit, recover the working directory based on the selected commit, and save the change in the commit log.

• Commit by using the default revert message:

  git revert --no-commit/-n <commit>

• Revert a merged commit:

  git revert --mainline/-m <parrent_num> <commit>

Reset

reset will take a previous commit, recover the working directory based on the selected commit, and drop all commits after the selected commit.

Mixed (Default) Reset

git reset [--mixed] as the default reset operation, changes the HEAD and index at the same time.

Before git reset b:

After git reset b:

To revert HEAD and main:

1. Use git reflogto search for the reference
2. Use git reset [ref] to move back

Checkout as a Reset Method

git checkout will only move the current HEAD to the specific position.

Before git checkout b:

After git checkout b:

A Normal HEAD points to the latest commit of a branch; A Detached HEAD is pointing to a specific commit other than a branch.

To make changes on a detached HEAD: create a new branch git checkout -b <branch_name> before commit.

To link the detached HEAD to a branch: git switch <branch_name>.

Soft Reset vs Hard Reset vs Mixed Reset

Git Amend

Modify the last commit message

git commit --amend -m <new_message> will modify the last commit message and keep anything else the same.

Empty Initial Commit

An empty commit allows creating a commit with no changes. It can help trigger certain actions such as CI/CD, or mark one project's history/milestone without introducing actual code changes:

git commit --allow-empty -m <empty_message>