View source for Downloading GEOS-Chem source code

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'''''[[Configuring your computational environment|Previous]] | [[GEOS-Chem directory structure|Next]] | [[Getting Started with GEOS-Chem]]'''''
#[[Minimum system requirements for GEOS-Chem|Minimum system requirements (and software installation)]]
#[[Configuring your computational environment]]
#<span style="color:blue">'''Downloading source code'''</span>
#*[[GEOS-Chem directory structure]]
#[[Downloading GEOS-Chem data directories|Downloading data directories]]
#[[Creating GEOS-Chem run directories|Creating run directories]]
#[[GEOS-Chem configuration files|Configuring runs]]
#[[Compiling GEOS-Chem|Compiling]]
#[[Running GEOS-Chem|Running]]
#[[GEOS-Chem output files|Output files]]
#[[Python tools for use with GEOS-Chem]]
#[[GEOS-Chem_coding_and_debugging|Coding and debugging]]
#[[GEOS-Chem_overview#Further_reading|Further reading]]


You can download the GEOS-Chem source code to your computer system using Git.  But the way in which you will download GEOS-Chem source code changed starting with [[GEOS-Chem 13.0.0]].  This was necessary due to structural modifications that were introduced in GEOS-Chem 13.0.0.

== For GEOS-Chem 13.0.0 and later versions ==

Detailed instructions may be found at the [https://geos-chem.readthedocs.io/en/latest/gcc-guide/02-build/get-code.html '''Download source code''' chapter of <tt>geos-chem.readthedocs.io</tt>]

== For GEOS-Chem 12.9.3 and earlier versions ==

The GEOS-Chem source code is maintained on Github.com at '''https://github.com/geoschem/geos-chem'''. All [https://github.com/geoschem/geos-chem/releases official GEOS-Chem releases] prior to 13.0.0 originated from that Git repository.

We also recommend that you view this video tutorial, which is posted at our GEOS_Chem Youtube channel: [http://youtube.geos-chem.org '''youtube.geos-chem.org''']:

{| border="1" cellspacing=0 cellpadding=5 
|-valign="top" align="center"
|[[Image:Getting_Started_with_GC_Thumbnail.png]]<br> [https://www.youtube.com/watch?v=LOobuuhNdAg '''<big>Click HERE to view</big>'''!]
|}

You can download the [[GEOS-Chem_12#Current_stable_version|latest stable version of GEOS-Chem]] by typing the following at the command line:

  git clone https://github.com/geoschem/geos-chem Code.X.Y.Z

This will create an exact copy (or clone) of the official GEOS-Chem repository to your local disk space in a directory named Code.X.Y.Z. You may name the code directory whatever you like, but we recommend using the [[GEOS-Chem_versions|version number]] (i.e. X.Y.Z) in the code directory name. For more information on the meaning of X.Y.Z, see our [[GEOS-Chem version numbering system]] page. Note that although you've named your code directory Code.X.Y.Z, this code will be the latest stable version of GEOS-Chem by default (which may or may not be version X.Y.Z). If you want to change GEOS-Chem versions, see the instructions below.

===Note for advanced users===

If you plan on developing GEOS-Chem updates to submit for inclusion in the standard model we recommend that you [https://help.github.com/articles/fork-a-repo/ fork the repository] on Github and clone it from your own account. You can then make a [https://help.github.com/articles/creating-a-pull-request/ pull request] when you are ready to submit updates to the [[GEOS-Chem Support Team]]. See [[Submitting_updates_for_inclusion_in_GEOS-Chem|these instructions]] for more information.

=== Choosing a different version ===

When you clone GEOS-Chem you will always get the master branch. This is the [[GEOS-Chem_12#Current_stable_version|current stable version of GEOS-Chem]].  You can determine the version label by typing <tt>git log --decorate</tt> within each repository and looking at the git tag string printed for the top-most commit. 

[[File:gchp Gittag.png|800px|thumb|Example output of git log. Notice tag name at top indicating what version this is.]]

If you would like an earlier version you can checkout the version tag for that specific version. To see a list of available tags for a repository type <tt>git tag</tt>. To checkout a tagged version type <tt>git checkout -b NewBranch tags/tagname</tt>, where NewBranch can be a name of your choosing.

You can download as many copies of the GEOS-Chem source code as you wish. For example, you might want to keep a clean source code directory and then have one or more source code directories that you use for development or debugging. Alternatively, you may use Git version control to keep all of your work in different branches of a single clone of the repository.


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'''''[[Configuring your computational environment|Previous]] | [[GEOS-Chem directory structure|Next]] | [[Getting Started with GEOS-Chem]]'''''