Version Control with Git: Git Cheatsheets for Quick Reference

Key Points

Automated Version Control	Version control is like an unlimited ‘undo’. Version control also allows many people to work in parallel.
Setting Up Git	GitHub Desktop is an easier way to start using version control on your local computer.
Creating a Repository	Local repositories can be set up and track changes in files.
Tracking Changes	Files can be stored in a project’s working directory (which users see), the staging area (where the next commit is being built up) and the local repository (where commits are permanently recorded). Always write a log message when committing changes.
Ignoring Things	The .gitignore file tells Git what files to ignore.
Remotes in GitHub	A local Git repository can be connected to one or more remote repositories. Use the HTTPS protocol to connect to remote repositories until you have learned how to set up SSH. git push copies changes from a local repository to a remote repository. git pull copies changes from a remote repository to a local repository.
Collaborating	git clone copies a remote repository to create a local repository with a remote called origin automatically set up.
Conflicts	Conflicts occur when two or more people change the same file(s) at the same time. The version control system does not allow people to overwrite each other’s changes blindly, but highlights conflicts so that they can be resolved.
Open Science	Open scientific work is more useful and more highly cited than closed. You should preserve and share your GitHub content in a scholarly repository.
Using Git from RStudio	Create an RStudio project

Git Cheatsheets for Quick Reference

• A great printable git cheatsheet is available in PDF from the GitHub training website.
• An interactive one-page visualisation about the relationships between workspace, staging area, local repository, upstream repository, and the commands associated with each (with explanations).
• Both resources are also available in other languages e.g. Spanish, French, and more

Glossary

change set

A group of changes to one or more files that are or will be added to a single commit in a version control repository.

commit

To record the current state of a set of files (a change set) in a version control repository. As a noun, the result of committing, i.e. a recorded change set in a repository. If a commit contains changes to multiple files, all of the changes are recorded together.

conflict

A change made by one user of a version control system that is incompatible with changes made by other users. Helping users resolve conflicts is one of version control’s major tasks.

HTTP

The Hypertext Transfer Protocol used for sharing web pages and other data on the World Wide Web.

infective license

A license, such as the GPL, that legally requires people who incorporate material under the infective license into their own work to also release under the same infective license (e.g. under the GPL license).

merge

(a repository): To reconcile two sets of changes to a repository.

protocol

A set of rules that define how one computer communicates with another. Common protocols on the Internet include HTTP and SSH.

remote

(of a repository) A version control repository connected to another, in such way that both can be kept in sync exchanging commits.

repository

A storage area where a version control system stores the full history of commits of a project and information about who changed what, when.

resolve

To eliminate the conflicts between two or more incompatible changes to a file or set of files being managed by a version control system.

revision

A synonym for commit.

SHA-1

SHA-1 hashes is what Git uses to compute identifiers, including for commits. To compute these, Git uses not only the actual change of a commit, but also its metadata (such as date, author, message), including the identifiers of all commits of preceding changes. This makes Git commit IDs virtually unique. I.e., the likelihood that two commits made independently, even of the same change, receive the same ID is exceedingly small.

SSH

The Secure Shell protocol used for secure communication between computers.

timestamp

A record of when a particular event occurred.

version control

A tool for managing changes to a set of files. Each set of changes creates a new commit of the files; the version control system allows users to recover old commits reliably, and helps manage conflicting changes made by different users.