Git

Software Size

• One way to measure software size is via source lines of code (SLOC)
• A modern piece of large software, such as an operating system, may have tens of millions of lines of code

Team Size

• Some software is developed by individuals
• Many applications are developed by large teams
• Thousands of developers may work on large application such as Windows or the Linux kernel

How can we help thousands of people work together to write millions of lines of code?

Version Control

• Version control systems are used to manage change to the source code of software systems
• These tools become critical as the size of software and teams increases

Google Docs

History

• Version control systems manage history of the codebase
• Mistakes can be undone
• Previous versions of the software can be used

Git

• Distributed version control system
• Originally developed to manage the source code of the Linux kernel
• Most widely used version control system today

Init

• We can create a new git repository using git init
• This creates the .git metadata directory
• This repository will have no commits or pointers to commits

Status

• git status can be use to check the current state of the repository

Example

> git init
Initialized empty Git repository...
> git status
On branch main

No commits yet

nothing to commit (create/copy files and use "git add" to track)

Commits

• At its core, git track states of the system known as commits

Staging

• Before files are committed, they must be staged

Add

• git add can be used to track and stage a file

Example

> git add main.py
> git status
Changes to be committed:
  (use "git rm --cached <file>..." to unstage)
        new file:   main.py

Commit

• git commit can be used to create a new commit
• The -m flag can be used to provide a message
• File names can be provided
• The -a flag will commit all changes

Log

• git log can show the commit history