Git

Overview

Git is a version control software integrate by default in any UNIX system. It can help developing code projects via commiting changes of the project and allow going back to previous versions of the project. Git is mainly used from the command line.

You can push your projects to online repositories like GitHub, GitLab or SourceForge and other.

Content

Basic Commands

• git --version - Displays the installed Git version.
• git clone PATH - Clones a repository from a remote source to the local machine.
• git status - Shows the current state of the repository.
• git add FILE - Stages a modified file for commit.
  • git add . - Stages all modified files for commit.
• git commit - Saves staged changes in Git.
  • git commit -m "Title of the change" -m "Description of the change"
• git push - Uploads changes to a remote repository (e.g., GitHub).
• git pull - Downloads updates from a remote repository.
• git init - Initializes a new repository in the current folder.
• git branch - Lists all branches.
• git branch NAME - Creates a new branch with the given name.
• git checkout HASH - Restores an old version.
• git checkout BRANCH-NAME - Switches to a different branch.
• git merge BRANCH-NAME - Merges changes from another branch into the current branch.
• git log - Displays the commit history.

Git Terminology

• Pull Request - A request to merge changes into a repository
• Merge - The process of combining changes from two versions
• Branch - A separate version of the repository used for parallel development
• Staging - Marking files for commit.
• Commit - Locally saving changes with a message
• Push - Uploading changes to a remote repository
• Fetch - Load changes from a Remote Repository without integrating in your current version. Needs to be merged or rebased for this
• Bisecting - search to find the commit that introduced a bug
• Stash - save changes temporarily, without committing

Git Configuration

• Set name and email for tracking changes:
  • git config --global user.name "YOUR NAME"
  • git config --global user.email "YOUR@MAIL.COM"
• Rename default branch:
  • git config --global init.defaultBranch NAME
• Rename current branch:
  • git branch -m NAME

Creating a Repository on GitHub

• Sign in to GitHub
• Create a new repository
• Create a README.md file for documentation
• commit new file to save it
• commit changes to track modifications
• Every commit has a unique identifier

Creating a Local Repository

• Run git init in the desired folder
• Stage all files with git add .
• Commit the changes with a message

Tracking Changes

• Open the file in GitHub
• Green lines - Additions
• Red lines - Removed lines before the change
• The .git folder stores the history of the repository

Saving Changes / Commit

• Check for modifications with git status
• Stage files with git add FILE or git add .
• Commit with git commit -m "TITLE" -m "DESCRIPTION"
• The change is now saved locally

Pushing Changes to a Remote Repository

• Connect your computer to GitHub with an SSH key
• Generate a key:
  • ssh-keygen -t rsa -b 4096 -C "Mail@somethi.ng"
    • -t rsa - Encryption type
    • -b 4096 - Key strength
    • -C - Email associated with GitHub
  • The .pub key must be added to GitHub
  • Add the SSH key to the SSH agent:
    • GitHub SSH Key Setup Guide
  • Push with:
    • git push origin main
      • origin - The remote repository
      • main - The branch

Cloning a Repository

• Open a terminal
• Navigate to the target directory with cd
• Use git clone LINK to download the repository

Merge two branches

Git Merge Two Branches

1. Switch to the target branch:

   • git checkout main or git switch main

2. Update the target branch (optional but recommended):

   • git pull origin main

3. Merge the other branch into the target branch:

   • git merge feature-branch

4. Resolve conflicts (if any):

   • Edit conflicted files
   • Mark resolved files: git add <conflicted-files>
   • Complete the merge: git commit

5. Push the changes to the remote repository:

   • git push origin main

6. If you want to avoid a fast-forward merge and keep a merge history:

   • git merge --no-ff feature-branch

7. To abort the merge (if not committed yet):

   • git merge --abort

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