Version control
Introduction
When working with computer files of any kind, keeping track of changes is important. For example, you may want to
- Keep track of who made what changes to a document - and why.
- Be able to quickly roll back to a previous version of your software after that new feature caused some unexpected behaviour.
- Run the version of your software that you used for that experiment last month.
A version control system like Git can greatly ease these activities, particularly when working with plain text file formats like source code and markup.
If you make some changes to a set of files or repository under version control, you then commit those changes with a short message describing why the changes were made. It is possible to review all the commits made, revert to any previously committed version, or to view the differences between any two versions. Specific versions can be tagged e.g. as releases.
Branches allow for multiple versions to exist in parallel. For example, you release version 1.0 of your software. It probably makes sense to maintain one branch for working on bugfixes for version 1.0 while working on the new features for 1.1 in another. These branches can later be merged. Branches are particularly useful when multiple people are working on something together, synchronising their repositories with a central server.
It is strongly recommended that all source code be placed under version control.
To learn more about version control in general and Git in particular, watch out for any Software Carpentry workshops being run at the University. You can take a look at the Software Carpentry material for the “Version Control with Git” lesson in your own time. If you want more detail, take a look at Pro Git by Scott Chacon and Ben Straub and published by Apress, available to read online.
GitHub
GitHub is a hosted Git repository service, widely used by open source projects. Anyone can register and create public repositories, with the ability to create private repositories available as a paid-for service. However, academics can get private repositories for free.
GitHub is a U.S. company and data they collect will be stored and processed in the United States. As such it is not appropriate for any data or code which is sensitive e.g. data which includes information which could be used to identify individuals or software developed with industrial partners which is commercially sensitive.
Take a look at GitHub’s documentation for help on getting up and running with the service.
Clients
Version control systems can typically be used either via command-line or graphical clients. In the case of Git, SourceTree and GitHub Desktop (for working with GitHub repositories) are good free graphical clients.
