git-commands: A repository from PhumrapeeC

Using Git

Basics
Adding and Changing Things
Undo Changes and Recover Files
Viewing Commits
Branch and Merge
Commands for Remotes
Favorites
Resources

Note on Paths

In this file, directory paths are written with a forward slash as on MacOS, Linux, and the Windows-Bash shell: /dir1/dir2/somefile.

Basics

When using Git locally, what are these? Define each one in a sentence
- Staging area - A place to organize changes before committing them.
- Working copy - Your local files where you make edits.
- master - The default name for the primary branch in a repository.
- HEAD - Points to your current working location in the repository.
When you install git on a new machine (or in a new user account) you should perform these 2 git commands to tell git your name and email. These values are used in commits that you make:
```
# Git configuration commands for a new account
git config --global user.name "Phumrapee Chaowanapricha"
git config --global user.email phumrapee.ch4352@gmail.com
```
There are 2 ways to create a local Git repository. Briefly descibe each one:
- Initializing: Use git init to start a new Git repository in a directory.
- Cloning: Employ git clone to copy an existing remote repository to your local machine.

Adding and Changing Things

Suppose your working copy of a repository contains these files and directories:

README.md
out/
    a.exe
src/a.py
    b.py
    c.py
test/
    test_a.py
    ...

Add README.md and everything in the src directory to the git staging area.
```
git add README.md src/
```
Add test/test_a.py to the staging area (but not any other files).
```
git add test/test_a.py
```
List the names of files in the staging area.
```
git status
```
Remove README.md from the staging area. This is very useful if you accidentally add something you don't want to commit.
```
git reset README.md
```
Commit everything in the staging area to the repository.
```
git commit -m "Your commit message here"
```
In any project, there are some files and directories that you should not commit to git.
For a Python project, name at least files or directories that you should not commit to git:
- pycache
- .pytest_cache
- venv
Command to move all the .py files from the src dir to the top-level directory of this repository. This command moves them in your working copy and in the git repo (when you commit the change):
```
git mv src/*.py .
```
In this repository, create your own .gitignore file that you can reuse in other Python projects. Add everything that you think is relevant.
Hint: A good place to start is to create a new repo on Github and during the creation dialog, ask Github to make a .gitignore for Python projects. Then edit it. Don't forget to include pytest output and MacOS junk.

Undo Changes and Recover Files

Display the differences between your working copy of a.py and the a.py in the local repository (HEAD revision):
```
git diff a.py
```
Display the differences between your working copy of a.py and the version in the staging area. (But, if a.py is not in the staging area this will compare working copy to HEAD revision):
```
git diff --staged a.py
```
View changes to be committed: Display the differences between files in the staging area and the versions in the repository. (You can also specify a file name to compare just one file.)
```
git diff --staged
```
Undo "git add": If main.py has been added to the staging area (git add main.py), remove it from the staging area:
```
git reset main.py
```
Recover a file: Command to replace your working copy of a.py with the most recent (HEAD) version in the repository. This also works if you have deleted your working copy of this file.
```
git checkout a.py
```
Undo a commit: Suppose you want to discard some commit(s) and move both HEAD and "master" to an earlier revision (an earlier commit) Suppose the git commit graph looks like this (aaaa, etc, are the commit ids)
```
git reset --hard bbbb
```
The command to reset HEAD and master to the commit id bbbb:
Checkout old code: Using the above example, the command to replace your working copy with the files from commit with id aaaa:
```
git checkout aaaa
```
Note:
- Git won't let you do this if you have uncommitted changes to any "tracked" files.
- Untracked files are ignored, so after doing this command they will still be in your working copy.

Viewing Commits

Show the history of commits, using one line per commit:
```
git log --oneline
```
Some versions of git have an alias "log1" for this (git log1).
Show the history (as above) including all branches in the repository and include a graph connecting the commits:
```
git log --graph --all --decorate --oneline
```

List all the files in the current branch of the repository:

git ls-tree -r HEAD --name-only

Example output:

.gitignore
README.md
a.py
b.py
test/test_a.py
test/test_b.py

Branch and Merge

Creating a New Branch: To create a new branch and switch to it
```
git checkout -b new-feature
```
Switching Between Branches: To switch to an existing branch
```
git checkout existing-branch
```
Merging Branches: To merge changes from one branch into another
```
git checkout target-branch
git merge source-branch
```
Viewing Branches: To see all branches and highlight the current one:
```
git branch
```
Rebasing: To integrate changes from one branch onto another:
```
git checkout feature-branch
git rebase main
```

Favorites

Rebasing a Feature Branch onto the Main Branch

First, ensure you're on the feature branch:
```
git checkout feature-branch
```
Perform the rebase, integrating changes from the main branch onto the feature branch:
```
git rebase main
```
If there are any conflicts, resolve them by editing the conflicted files, then:
```
git add conflicted-file
git rebase --continue
```
Once the rebase is complete, your feature branch's commits are now on top of the main branch's commits.
If necessary, you can force push the rebased feature branch to update the remote repository:
```
git push -f origin feature-branch
```

Resources

Git Tutorial Git - Basic Concepts
Pro Git Online Book Chapters 2 & 3 contain the essentials. Downloadable e-book is available, too.
Visual Git Reference one page with illustrations of git commands.
Markdown Cheatsheet summary of Markdown commands.
Github Markdown some differences in the way Github handles markdown and special Markdown for repos.

Learn Git Visually:

Learn Git Interactive Tutorial great visual tutorial
Git Visualizer execute Git commands in a web browser and see the results as a graph.

PhumrapeeC/git-commands