# Git Basics

This guide serves as a summary of [Atlassian's Git Tutorial](https://www.atlassian.com/git/glossary#commands)

For more tutorials:
- [CLion Git Tutorial](https://www.jetbrains.com/help/clion/using-git-integration.html)
- [VSCode Git Tutorial](https://code.visualstudio.com/docs/sourcecontrol/intro-to-git)
- [PyCharm Git Tutorial](https://www.jetbrains.com/help/pycharm/using-git-integration.html)
- [IntelliJ Git Tutorial](https://www.jetbrains.com/help/idea/using-git-integration.html)
- [OhMyGit](https://ohmygit.org)
- [Learn Git Branches](https://learngitbranching.js.org)


### git clone
- Git clone is used to replicate a repository from Github
- A clone copies an existing repo this is not a file-based interaction
- A cloned repository has it's own history, manages, it's own files, completely isolated environment from the original repository
``` bash
git clone git@github.com:organization/
cd my-project 
# Start working on the project
```

### git branch
**Reasons to use branches**
1. Collaboration: avoid merge conflicts
2. Long Term Development: 
    - If a feature takes 1-2 weeks to develop you should be pushing changes as you work
    - Pushing this developement to master ruins the opportunity for someone else to work on a new feature or revert to an old version in case of issues
3. Multiple Feature Development 
    - If you need to work on 2 features at once, maybe one feature takes less time than expected and is ready to be released
    - If both are on your local master you must go back and remove code for feature 2 or wait to release until both features are completed
        - what if one feature had an issue? Both would need to be reverted
**how to use:**
- Branches are used to make a local copy of cloned respository where changes can be made without affecting master
- This helps keep code safe!
[Examples and more information](https://www.atlassian.com/git/tutorials/using-branches)
``` bash
git branch
* master

git checkout -b demo-branch
Switched to a new branch 'demo-branch'

git branch 
* demo-branch
  master

git checkout master
Your branch is up to date with 'origin/master'.

git branch
  demo-branch
* master

git branch -d demo-branch
Deleted branch demo-branch (was 216f16e).

git branch
* master
```

### git add
Git add moves a file change from the working directory to the staging area. Git now knows these updates to a file are to be added to the next commit. This does not affect the repository until you run git commit.
**Common Usage:**
- git add <file>
- git add <directory>
- git add . 

### git commit
Git commit captures the state of a project at that point in time and prepares all changes to be added to the repository after a git push.
**Common Usage:**
- git commit
- git commit -a 
- git commit -m "commit message"
- git commit -am "commit message"
- git commit --amend

### git push
Git push is used to upload local repository content to a remote respository. Commits are transferred from your local repository to the remote repository during a push.
**Common Usage:**
- git push <remote> <branch>
- git push <remote> --force

### git pull
Git pull is used to fetch and download content from a remote repository and immediately update the local repository to match that content. Merging remote upstream changes into your local repository is a common and important task in Git. The git pull command first runs git fetch which downloads content from the specified remote repository. Then a git merge is executed to merge the remote content refs and heads into a new local merge commit.
**Common Usage:**
- git pull
- git pull --no-commit <remote>
- git pull --rebase <remote>

### git diff
Used for taking 2 git data sources and comparing them. These data sources include: commits, branches, files, and more. By default git diff will show you any uncommitted changes since the last commit. 
**Common Usage:**
- git diff branch1..branch2
- git diff branch1 branch2 <file name>

### git status
Git status displays the current state of the working directory and the staging area. It lets you see which changes have been staged, which haven't, and which files aren't being tracked by Git. Status output does not show you any information regarding commit project history, for this use git log.

### git reset
Git reset is a command used for undoing changes. It is useful when you want to undo commits that have not been pushed to a remote repository. Also a useful command to remove commits that contain mistakes or are no longer necessary.
**Three primary forms**
- soft - updates reference pointers but leaves the changes untouched in the staging area and working directory
- mixed - (default) staging index is reset, these changes are moved to the working directory
- hard - any pending work that was in the staging area and working directory will be lost