Git Basics 01

1- Installation and setup

The most common way to use Git is via a command-line program called git, which lets us transform an ordinary Unix directory into a repository (or repo for short) that enables us to track changes to our project

Check if Git is already installed: start the terminal window and use which (you should have already installed this when installing linux)
```
 $ which git
 /usr/local/bin/git
```
If its not there, install Git: You can either use some pacakage management tool or depending on your distro use the command line to install it. For example on Ubuntu you would write:
```
 sudo apt install git-all
```
After installing Git but before starting a project, we need to perform a couple of one-time setup steps for Git to identify your changes by name and email
```
 $ git config --global user.name "Your Name"
 $ git config --global user.email your.email@example.com
```
Git stores global configuration settings in a hidden text file located in your home directory. By inspecting the file ~/.gitconfig with a tool of your choice (cat, less, a text editor, etc.), confirm that the configuration you set up corresponds to simple text entries in this file.

2- Initializing the repo

Start creating a project and put it under version control with Git

Make a directory with the generic name website inside a repositories directory called repos using the following command:
```
 [~]$ mkdir -p repos/website
```
Even though the website directory is empty, we can already convert it to a repository, which is like an enhanced directory with the additional ability to track changes to every file and subdirectory. The way to create a new repository with Git is with the init command, which creates a special hidden directory called .git where Git stores the information it needs to track our project’s changes.
```
 [website]$ git init
```

3- Making our first commit

Git won’t let us complete the initialization of the repository while it’s empty, so we need to make a change to the current directory.

Create a main page index.html using the following command:
```
 touch index.html
```

Use the git status command to see the result. It would look something like this:

 [website (master)]$ git status
 On branch master

 Initial commit

 Untracked files:
 (use "git add <file>..." to include in what will be committed)

 index.html

 nothing added to commit but untracked files present (use "git add" to track)

A file that is “untracked” means Git doesn’t yet know about it. We can add it using the git add command

Use the git add command with -A or with . which tells Git to add all untracked files.
```
 [website (master)]$ git add -A
```
or
```
 [website (master)]$ git add .
```
The status of the file has now been promoted from untracked to staged, which means the file is ready to be added to the repository.
After putting changes in the staging area, we can make them part of the local repository by committing them using git commit. You can think of a commit as a snapshot of the Git repository. Use the command-line option -m to include a message indicating the purpose of the commit.
```
 [website (master)]$ git commit -m "Initialize repository"
```
Use git log to see a record of your commit:
```
[website (master)]$ git log
commit 879392a6bd8dd505f21876869de99d73f40299cc
Author: Michael Hartl <michael@michaelhartl.com>
Date:   Thu Dec 17 20:00:34 2015 -0800

Initialize repository
```
A commit is identified by a hash, which is a unique string of letters and numbers that Git uses to label the commit and which lets Git retrieve the commit’s changes.

This is the main Git status sequence for changing a file:

3- Viewing the diff

It’s often useful to be able to view the changes represented by a potential commit before making it.

Let us add something to our index.html file like the text hello, world.

Lets now use git diff, which by default just shows the difference between the last commit and unstaged changes in the current project:

 [website (master)]$ git diff
 diff --git a/index.html b/index.html
 index e69de29..4b5fa63 100644
 --- a/index.html
 +++ b/index.html
 @@ -0,0 +1 @@
 +hello, world

Having a Git repository for your project is very useful, but lets take it up a level and see how we can use Git for collaboration. Get to the next documentation.

Resources
1. https://www.learnenough.com/git-tutorial/getting_started
2. https://classroom.udacity.com/courses/ud775/lessons/2969618657/concepts/29605487770923

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Last updated 4 years ago

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