Version control with Git

Overview

Git is a relatively new version control system. At present (March 2010), we are considering migrating the GEOS-Chem repository from CVS to Git, for a variety of reasons:

• Git avoids some of the limitations of CVS (which is by now 20-year-old software).
• Git is in general much simpler to use than CVS.
• With Git, GEOS-Chem developers will be able to:
  1. Download the most current GEOS-Chem source code online. (This will obviate the need for having to download the *.tar.gz files.)
  2. Develop and test their source code additions to GEOS-Chem in their own local repository, and
  3. Submit their mature source code updates back to the GEOS-Chem Support Team for inclusion in the standard mainline code

Tutorials about Git

For beginners

Git tutorial video

Excellent lecture given by Bart Trojanowski for the Ottawa Group of Ruby Enthusiasts. HIGHLY RECOMMENDED!

Git for Designers

Nice overview of how version control works. Recommended for people with no prior experience using a version control system.

Git for the Lazy

This is an excellent Git guide for beginners. Short, sweet, and to the point.

Overview of Git and Subversion

Presentation given by the School of Engineering and Applied Sciences at Harvard.

For more advanced users

Git From the Bottom Up by John Wiegley

Article which not only describes the commands used to invoke Git but also the design philosophy behind the Git version control system. Good theoretical background but somewhat terse for beginners to understand.

Official Git tutorial

A comprehensive but somehwat terse tutorial of Git commands.

Git for CVS Users

A tutorial specifically geared toward migrating from CVS to Git.

Sending Patches with Git

A guide how to use the patch feature of Git to send your changes to another user.

Using Git with GEOS-Chem and GAMAP

Obtaining and installing Git

If you don't already have Git on your system then you (or your sysadmin) will have to install it. To check if it is already installed, you can ask for the version at the Unix prompt. Type:

[534 rhea GEOS_5]% git --version

If you get a string similar to:

git version 1.6.6.2

then you are good to go. (The actual version # doesn't matter.) If not, then you (or your sysadmin) may obtain the Git source code (or binaries) the Git website.

First-time setup

Before using Git for the first time, you need to set up your ~/.gitconfig file. Open a text editor and then cut & paste the text from this sample .gitconfig file. Then save it as ~/.gitconfig.

Be sure to change your name and email accordingly, this is how Git will know who you are!

Please see the following pages which describe how to download the GEOS-Chem and GAMAP source code packages via Git.

Downloading GEOS-Chem and GAMAP

Please see the following wiki pages which contain detailed information about how to use Git to download and modify the GEOS-Chem and GAMAP source code packages:

• Using Git with GEOS-Chem
• Using Git with GAMAP

--Bob Y. 09:43, 16 March 2010 (EDT)

References

1. Git web page
2. Git Cheat Sheet
3. Google "Tech Talk" by Linus Torvalds, the creator of Git (Video on Youtube)
4. Google "Tech talk" by Randal Schwartz (Video on Youtube)
5. Setting up your .gitconfig file (Link)

--Bob Y. 15:41, 9 March 2010 (EST)