This lesson is being piloted (Beta version)

Version Control with Git: Git Cheatsheets for Quick Reference

Key Points

Introduction to the workshop

  • Sticky notes are signals to the instructor(s) and helper(s) during the class.

  • Blue-green is Yes / Good / Agree / I’m Caught Up.

  • Orange is No / Alert / Disagree / I Need Help.
Setting Up Git

  • Use git config to configure a user name, email address, editor, and other preferences once per machine.
Creating a Repository

  • GitHub makes creating a new repository very easy.
Tracking Changes

  • git status shows the status of a repository.

  • 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).

  • git add puts files in the staging area.

  • git commit saves the staged content as a new commit in the local repository.

  • Always write a log message when committing changes.
Labeling Things and Undoing Things

  • Tags are human-friendlier ways of identifying a specific commit than hexadecimal codes. A tag stays with its commit and identifies one point in time.

  • Branches are names that will move forward as you add more commits. Branches identify lines of thought or particular variations.

  • git checkout brings specified versions into your working directory for investigation.

  • git checkout -b creates a named branch during checkout so that you won’t develop new code from a detached HEAD.

  • git reset removes commits from your history - use with caution!

  • git revert makes a new commit that counteracts the commits you want to undo.

  • Always write a log message when committing changes.
Pushing and Pulling to and from GitHub

  • A local Git repository can be connected to one or more remote repositories.

  • git push copies changes from a local repository to a remote repository.

  • git pull copies changes from a remote repository to a local repository.
Ignoring Things

  • The .gitignore file tells Git what files to ignore.
Forks and Pull Requests

  • Any public repository on GitHub can be forked and modified.

  • If you make changes to a forked repository, you can request that the maintainer of the original repository merges your changes into theirs.
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.
Sharing one repository

  • git clone copies a remote repository to create a local repository you can collaborate on.

Git Cheatsheets for Quick Reference

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.