Instructor Notes
Tips and Tricks
Known problems that learners encounter:
Windows: When using an outdated version of Windows OpenSSH, learners cannot set up the SSH connection to GitHub. SOLUTION: Update OpenSSH version.
Making a handout
To make a handout for this lesson, adapt/print from https://librarycarpentry.org/lc-git/reference.html.
General notes on Git
Using a software tool to handle the versions of your project files lets you focus on the more interesting/innovative aspects of your project.
- Version control’s advantages
- It’s easy to set up
- Every copy of a Git repository is a full backup of a project and its history
- A few easy-to-remember commands are all you need for most day-to-day version control tasks
- The GitHub hosting service provides a web-based collaboration service
- Two main concepts
- commit: a recorded set of changes in your project’s files
- repository: the history of all your project’s commits
- Why use GitHub?
- No need for a server: easy to set up
- GitHub’s strong community: your colleagues are probably already there
Overall
Version control might be the most important topic we teach, but Git is definitely the most complicated tool. However, GitHub presently dominates the open software repository landscape, so the time and effort required to teach fundamental Git is justified and worthwhile.
Because of this complexity, we don’t teach novice learners about many interesting topics, such as branching, hashes, and commit objects.
Instead we try to convince them that version control is useful for researchers working in teams or not, because it is
- a better way to “undo” changes,
- a better way to collaborate than mailing files back and forth, and
- a better way to share your code and other scientific work with the world.
Teaching Notes
Resources for “splitting” your shell so that recent commands remain in view: https://github.com/rgaiacs/swc-shell-split-window.
Make sure the network is working before starting this lesson.
Drawings are particularly useful in this lesson: if you have a whiteboard, use it to visualise and describe the GitHub flow.
Version control is usually not the first subject in a workshop, so get learners to create a GitHub account after the session before. Remind learners that the username and email they use for GitHub (and setup during Git configuration) will be viewable to the public by default. However, there are many reasons why a learner may not want their personal information viewable, and GitHub has resources for keeping an email address private.
If some learners are using Windows, there will inevitably be issues merging files with different line endings. (Even if everyone’s on some flavor of Unix, different editors may or may not add a newline to the last line of a file.) Take a moment to explain these issues, since learners will almost certainly trip over them again. If learners are running into line ending problems, GitHub has a page that helps with troubleshooting.
We don’t use a Git GUI in these notes because we haven’t found one that installs easily and runs reliably on the three major operating systems, and because we want learners to understand what commands are being run. That said, instructors should demo a GUI on their desktop at some point during this lesson and point learners at this page.
Instructors should show learners graphical diff/merge tools like DiffMerge.
When appropriate, explain that we teach Git rather than CVS, Subversion, or Mercurial primarily because of GitHub’s growing popularity: CVS and Subversion are now seen as legacy systems, and Mercurial isn’t nearly as widely used in the sciences right now.
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Further resources:
- git-it is a self-paced command-line Git demo, with git-it-electron its GitHub Desktop successor.
- Try GitHub’s resources to learn Git or Codeacademy’s Learn Git.
- For instructors, the Git parable is useful background reading.