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Pushing to a remote git repository

Set up and pull

You now need to start working with your own private remote repository in github. This requires some extra steps, but most of the time you can work locally: do your editing, compilation and experiments within your local repository, and only "push" to your remote repository as necessary. Any local commits will be stored up and remembered, then sent to the remote copy at the next push.

You started the coursework by cloning the remote origin repository:

https://github.com/HPCE/hpce_2014_cw3  (v1)
 |              
 |  Clone                ^
 V                     origin 
/home/dt10/hpce_2014-cw3 (v1)

Your local repository is then yours to work with, and you can do a number of edits and commits. For example, lets say you change and add some local files, taking your local version up to "v4":

https://github.com/HPCE/hpce_2014_cw3  (v1)
 :
 :                        ^
 :                      origin 
/home/dt10/hpce_2014-cw3 (v4)

If I were to now make some changes to the origin repository, the two would be out of sync. Let's say I modified readme.md, taking my copy to version "v7". You could then "pull" those changes, which would get integrated into your local repository:

https://github.com/HPCE/hpce_2014_cw3  (v7)
 |
 |  git pull              ^
 V                      origin
/home/dt10/hpce_2014-cw3 (v9)

The version numbers I'm using are quite notional, as git does not support linear dependencies, it uses a DAG of changes.

Pushing to a remote private repository

You should have been given a remote repository on github that you have read/write access to, and is visible in the website. The name I used was hpce_2014_cw3_login, so in my case it is hpce_2014_cw3_dt10. I now want to add that repository as a new place I can push to, while keeping the link to the "origin" source (this is actually what github will say as well if you look at your repository).

I can use git remote add to do this:

git remote add private git@github.com:HPCE/hpce_2014_cw3_dt10.git

This has set up a new relationship between my local repository and a different remote:

https://github.com/HPCE/hpce_2014_cw3  (v7)
 :
 :                        ^
 :                      origin
/home/dt10/hpce_2014-cw3 (v9)
 :                      private
 :                        v
 :
git@github.com:HPCE/hpce_2014_cw3_dt10.git (v0)

I can now "push" my local repository into the private copy, using:

git push -u private master

which does:

https://github.com/HPCE/hpce_2014_cw3  (v7)
 :
 :                        ^
 :                      origin
/home/dt10/hpce_2014-cw3 (v9)
 |                      private
 |  Push                  v
 V
git@github.com:HPCE/hpce_2014_cw3_dt10.git (v9)

You local and private repository are now in sync and should be identical. You could now continue to make edits and commits in your local repository, taking it up to "v11" (again, these version numbers are artificial):

https://github.com/HPCE/hpce_2014_cw3  (v7)
 :
 :                         ^
 :                       origin
/home/dt10/hpce_2014-cw3 (v11)
 :                       private
 :                         v            
 :                                      
git@github.com:HPCE/hpce_2014_cw3_dt10.git (v9)

which could then be pushed back up to your private repo:

https://github.com/HPCE/hpce_2014_cw3  (v7)
 :
 :                         ^
 :                       origin
/home/dt10/hpce_2014-cw3 (v11)
 |                       private
 |                         v
 | git push private master
 V
git@github.com:HPCE/hpce_2014_cw3_dt10.git (v9)

If I were to make updates to the origin repository taking it to v13, you could continue to integrate those changes by pulling from "origin":

https://github.com/HPCE/hpce_2014_cw3  (v13)
 |
 |  git pull origin master
 |                          ^
 V                       origin
/home/dt10/hpce_2014-cw3 (v13)
 :                       private
 :                         v
 :
git@github.com:HPCE/hpce_2014_cw3_dt10.git (v9)

which would get integrated, then could be pushed back to your private repository.

Working on a remote machine

One of the things you often need to do is to work on a remote machine with different hardware, for example AWS in our case. git makes it easy to get a working copy which can stay in sync.

So from your remote machine, do:

ssh git@github.com

to check that you are correctly authenticated.

You can now clone your private github repository:

git clone git@github.com:HPCE/hpce_2014_cw3_dt10.git

This will give you another "local" repository, except it will be on another machine:

https://github.com/HPCE/hpce_2014_cw3  (v13)
 :
 :                         ^
 :                       origin
/home/dt10/hpce_2014-cw3 (v13)
 :                       private                   
 :                         v
 :
git@github.com:HPCE/hpce_2014_cw3_dt10.git (v13)
 |
 |  git clone ...          ^
 V                       origin
/home/dt10/hpce_2014-cw3 (v13)

The two "local" repositories are not directly connected, but can communicate via the private remote. So once you have tried your code out on the remote server and made some commits there, taking it up to v15, you can bring them back with a push from the remote machine:

https://github.com/HPCE/hpce_2014_cw3  (v13)
 :
 :                         ^
 :                       origin
/home/dt10/hpce_2014-cw3 (v13)
 :                       private
 :                         v
 :
git@github.com:HPCE/hpce_2014_cw3_dt10.git (v15)
 ^
 |  git push origin        ^
 |                       origin
/home/dt10/hpce_2014-cw3 (v15)

From there, you can bring the changes back to your local working repository using another pull.