In the last edition, I tried to elucidate the point that GIT is the most efficient source management tool for open source projects. In this edition, I will illustrate how to implement GIT and create a GIT repository for your project.

Please note that I’m going to use one of the Java programs that I wrote a few months back (It is a Java web application that uses Spring, Hibernate frameworks and DWR tools. But you don’t require knowledge in Java for doing this tutorial.).

Installing GIT in your system

Since GIT is very popular you can easily install it using an standard install command (specific to your distribution). You may also look at the distributions repository to check that the software is available. In my system (Ubuntu) I used:

sudo apt-get -y install git-core gitosis

This will install the GIT core and the gitosis package. Fedora users may try ‘yup’ and OpenSuse users can find this in the YaST2 listing. If everything fails, try installing from source.

Once you have installed the software, you can add the project to it. First of all, go to the directory where the tarball (source code) of the project is located and then untar it to the directory.

aasisvinayak@GNU-BOX:~/Desktop/git_tutorial$ tar xzf Java_app.tar.gz

aasisvinayak@GNU-BOX:~/Desktop/git_tutorial$ cd Java_app

Now initialize GIT to create an empty git repository and GIT will inform you that the directory has been created:

aasisvinayak@GNU-BOX:~/Desktop/git_tutorial/Java_app$ git init-db

Initialized empty Git repository in /home/aasisvinayak/Desktop/git_tutorial/Java_app/.git/

Now, GIT will again ask you to add your first commit statement (default) after adding the files.

You may add your own custom commit line in the editor and save the file.

Now you can see that GIT is creating modes and adding ‘files’ to the ‘master branch’.

You may install ‘Giggle’ in order to view the GIT graph.

Tracking Changes in GIT

Edit a particular file in the project and add one or two files to it (for testing).

In my case I’m going to use ‘GamesScheme.java’.And as you can see I have added a comment line for testing.

Now I need to issue the following command in order to add the edited file to the repository.

aasisvinayak@GNU-BOX:~/Desktop/git_tutorial/Java_app$ git add ./src/java/esd/cw/model/GamesScheme.java

If I want to see the change, I can simply issue:

git diff  –cached

And I could see the difference:

After reviewing the difference and  I need to issue

aasisvinayak@GNU-BOX:~/Desktop/git_tutorial/Java_app$ git commit

This command will allow me to finalise my changes and add that to the branch in which I was working (master). I can also add the ‘commit’ comment at this stage.

It will also summarise the changes:

[master f199bc0] tested GIT techblog.aasisvinayak.com

1 files changed, 1 insertions(+), 0 deletions(-)

Now this will also be visible when you see the graph structure.

And when you browse through the source code using Giggle, you can actually see the changes (along with the name and details of the person who added the code).

There are various other GUI tools which you can try out. Here is another one:

Maintaining an online repository

You have two choices here:

• Install GIT in your server and manage it from there
• You can host that in a public server like Gitorious

In these cases, you need to configure some global setting for GIT. In my case I need to add:

aasisvinayak@GNU-BOX:~$ git config –global user.name  "Aasis Vinayak"
aasisvinayak@GNU-BOX:~$ git config –global user.email aasisvinayak@gmail.com

The only difference in this case is that the you need to use your RSA/DSA key each time you connect to the server and you may have to add the GIT URL along with the commands.

For example, if you want to pull the repository you may use:

git pull git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git

(You can use ‘git clone’ for getting the source)

For switching to master you can use

git checkout master

Then make the changes by issuing:

git remote add origin git@yourdomain_name.com:sample-java-project-for-techblog/sample-java-project-for-techblog.git
git push origin master

We will be covering more GIT commands and tools in the ‘Kernel Dev’ section.