Version Control with Git: Local

You have been hired by Universal Missions (a space services spinoff from Euphoric State University) to investigate if it is possible to send a planetary lander to Mars. You need to work and record your observations about this planet, but you also want to make sure your changes are recorded in real time and can be accessed later, if necessary. Your general practice up until now has been taking notes in a word document and uploading that document to your group’s Dropbox account when you get internet access, but somethings things get overwritten and your collaborators sometimes move your files around haphazardly.

A colleague suggests using version control to manage your work. Version control is better than mailing files back and forth to your collaborators because:

• Nothing that is committed to version control is ever lost, unless you work really, really hard at it. Since all old versions of files are saved, it’s always possible to go back in time to see exactly who wrote what on a particular day, or what version of a program was used to generate a particular set of results.

• As we have this record of who made what changes when, we know who to ask if we have questions later on, and, if needed, revert to a previous version, much like the “undo” feature in an editor.

• When several people collaborate in the same project, it’s possible to accidentally overlook or overwrite someone’s changes. The version control system automatically notifies users whenever there’s a conflict between one person’s work and another’s.

Teams are not the only ones to benefit from version control: lone researchers can benefit immensely. Keeping a record of what was changed, when, and why is extremely useful for all researchers if they ever need to come back to the project later on (e.g., a year later, when memory has faded).

Version control is the lab notebook of the digital world: it’s what professionals use to keep track of what they’ve done and to collaborate with other people. Every large software development project relies on it, and most programmers use it for their small jobs as well. And it isn’t just for software: books, papers, small data sets, and anything that changes over time or needs to be shared can and should be stored in a version control system.

Prerequisites

In this lesson we use Git from the Unix Shell. Some previous experience with the shell is expected, but isn’t mandatory.