Git Tutorial for a local project

In this tutorial, you will learn Git basics, and you will study how to do branching and merging, which are very important when you work as a team on a project.

• For Linux and Unix based users, you can simply run a command to install git as http://git-scm.com/download/linux.

• For Windows users, navigate to http://git-scm.com/downloads to download the client. To be able to run all the Unix commands provided in this tutorial, you might want to select the option as shown in the screenshot. Otherwise, you may use cygwin.
  
  

1. You can introduce yourself to Git with your username and email address before doing any operation by:

   $ git config --global user.name "Your Name"
   $ git config --global user.email "you@example.com"

   Please use your actual email because it will be used as an identification of your Git commits for remote repository in the next tutorial. This information will be written to .gitconfig under your home directory.

2. To see the current username and email address on Git, you may enter the following commands:

   $ git config user.name
   Your Name
    
   $ git config user.email
   you@example.com

Unlike SVN, you may use Git on your local project without any centralized server. To get started you will need to initialize a repository.

1. Create a new folder for your project:

   $ mkdir YOUR_PROJECT
   $ cd YOUR_PROJECT

2. Initialize a repository within the folder:

   $ git init
   Initialized empty Git repository in /YOUR_PROJECT/.git/

Now, this folder is already Git. From now on, every commit operation will put your changes into your local repository. You can copy this folder to another machine and it will work. You need to do your first commit to make this light up.

1. Use your favorite text editor to create a blank text file “README.txt”. Otherwise, you may use a command to create a new text file:

   $ touch README.txt

2. Tell Git to track this file by add and commit:

   $ git add README.txt
   $ git commit -m "First commit"
   [master (root-commit) 52b149c] First commit
    1 file changed, 0 insertions(+), 0 deletions(-)
    create mode 100644 README.txt

   Now lets see what this visually looks like. (A) is the first commit. The default branch that gets created with Git is a branch names master. The pointer (*) means the reference to the commit that you are currently working on or what Git calls HEAD.
   
   
   

3. Add the text “this is a README” on the first line of README.txt, for example, by a command:

   $ echo this is a README > README.txt

4. Then commit new changes:

   $ git add README.txt
   $ git commit -m "Second commit"
   [master f4a9975] Second commit
    1 file changed, 1 insertion(+)

5. Also, commit log can be seen by:

   $ git log
   commit f4a997566f2289c40bc8895b9f64d25ebd6613f7
   Author: ***
   Date:   ***
    
       Second commit
    
   commit 52b149c7b167408831baed75b378ae909ed86349
   Author: ***
   Date:   ***
    
       First commit

   Now lets see what this visually looks like. (B) is the second commit, master branch moves to commit (B) with the current pointer (*) along.
   
   
   From log, 52b149c… represents the commit (A), while f4a9975… represents the commit (B). You may see the changes between commits by:

   $ git diff 52b149c...f4a9975
   diff --git a/README.txt b/README.txt
   index e69de29..79c4409 100644
   --- a/README.txt
   +++ b/README.txt
   @@ -0,0 +1 @@
   +this is a README

   Besides, you may switch your working commit by checkout (Note that cat is the command to view contain of file):

   $ git checkout 52b149c
   HEAD is now at 52b149c... First commit
   $ cat README.txt
    
   $ git checkout f4a9975
   Previous HEAD position was 52b149c... First commit
   HEAD is now at f4a9975... Second commit
    
   $ cat README.txt
   this is a README

   Make sure that you are at the commit (B) before following the next step.

6. Suppose we want to work on a bug. We start by creating a new branch for this work by checkout:

   $ git checkout -b bug123
   Switched to a new branch 'bug123'

   Notice that the new branch is created as a pointer to the current commit (B) and our current pointer (*) is moved to bug123 branch.
   
   
   You may see your current branch by:

   $ git branch
   * bug123
     master

7. Append the text “fix a bug” on the second line of README.txt, for example, by a command:

   $ echo fix a bug >> README.txt

   You may see the changes in README.txt by:

   $ cat README.txt
   this is a README
   fix a bug

8. Then commit the changes:

   $ git add README.txt
   $ git commit -m "Fix bug123"
   [bug123 a1bf88f] Fix bug123
    1 file changed, 1 insertion(+)

   Now, this visually looks like:
   
   
   You may see the changes between brunch master and bug123 by:

   $ git diff master..bug123
   diff --git a/README.txt b/README.txt
   index 79c4409..2c44363 100644
   --- a/README.txt
   +++ b/README.txt
   @@ -1 +1,2 @@
    this is a README
   +fix a bug

9. Let’s say the bug has been fixed, we want to merge these changes into the master branch. To do so, we first checkout to the master branch.

   $ git checkout master
   Switched to branch 'master'
    
   $ git branch
     bug123
   * master

   Now, we switched back to master branch, the current pointer (*) is moved.
   
   
   Let’s see what we have now in README.txt:

   $ cat README.txt
   this is a README

10. We did not merge a bug fixed from the bug123 branch to the master brunch yet. So, we then merge from the bug123 branch, bringing those change histories together:

    $ git merge bug123
    Updating f4a9975..a1bf88f
    Fast-forward
     README.txt | 1 +
     1 file changed, 1 insertion(+)
     
    $ cat README.txt
    this is a README
    fix a bug

11. And since we’re done with the bug123 branch, we can delete it by:

    $ git branch -d bug123
    Deleted branch bug123 (was a1bf88f).

    At the end, this is what it looks like: