This git glossary contains definitions of terms used in this repository.
There is another dcoument that describes a mental model of git that when understood can help one master git concepts at a deeper level.
A clean commit history is one where each commit is easy to understand and tells a story about how the project
evolved. It is clear when features were added and who added them. Each commit is a solid piece of work and
represents a milestone in the implementation of a feature or fix.
This clean commit history is not something that you need to think about while implementing a feature or fix.
Rather make commits as often as makes sense to you and your work environment.
Once the change is complete, think about what would be most useful for others to know about the change,
compress the commits into the fewest commits needed (usually just one) and provide a good commit comment.
There are a variety of tools one can use to clean
up the commit history of local changes before creating a pull request to share those changes with the rest
of the project team. The git merge --squash command is one the options available for cleaning up local
commit hsitory. The important concept is that the detailed steps (commits) that
were made while developing a feature or fix do not have to be the same detailed steps (commits)
shared with others.
Another aspect of a clean history is a linear history free of unnecessary merge commits. It is possible
to maintain a linear commit history by using the git rebase command on local changes before
creating a pull request to share your changes with the rest of the project. See
Merging vs. Rebasing for more information.
A clone of a github repository is a local copy of a repository residing on github. git maintains
a set of symbolc refernces to URL's for remote repositories. After the clone operation is complete, git sutomatically
creates a symbolic reference called origin to the remote URL from which the repository was cloned. The git
command git remote -v lists the remote symbolic referneces that git know about along with the URL associated with
each remote symbol.
As a noun: A single point in history of a repository. The entire history of a project is represented as a set of interrelated commits. Each commit is uniquely identified by a 40-character hexadecimal string which is created using a hash function, also referred to has the SHA of the commit. Sometimes the SHA is abbreviated to the first 7 characters of the 40-character string.
As a verb: The action of storing a new snapshot of the project's state in the Git history, by creating a new commit.
A fork is a copy of a repository. Forking a repository allows you to freely experiment with changes without affecting the original project. Forks can be used to propose changes to someone else's project or as a starting point for your own project.
Forking a repository is usually performed using the web interface for the remote hosting service (sush as github). The forked remote repository maintains a connection to the remote repository from which it was forked.
An object which contains the information about a particular commit.
git is a modern version control system used to maintain a history of changes to source code for a project. git has a
distributed architecture and is an examnple of a DVCS (Distrubuted Version Control System). Rather than have only a single
place where the full version historyof the software is stored (like CVS or Subversion), in git every developer's working copy
of the code is also a repository that can contain the full history of all changes.
github is a website and a service that maintains remote git repositories for project teams. Developers can interact with
these remote repositories stored on gtihub using the web interface. If you clone a repository to your development
machine, you can interact with the remote repository using the git command line interface.
You must have an account to make changes to repositories stored on github. There are two types of github accounts, organization
and individual. The organization account is often where the main repository for large open source projects resides.
The person (or persons) with access to the organization account control who can make changes to the remote repositories owned by
the organization account.
Invidivual accounts are needed by developers who may want to make changes to repositories owned by organizational accounts when the fork/clone development workflow is beihng used by the organization. When individuals want to make changes to a organization repository they can create a pull request. The pull request is reviewed and if approved will be merged into the organization repository.
A collection of references to commit objects and an object database of commit objects.
A string name that points to a repository. The value associated with a remote is the URL used to access the remote repository. A remote serves as a short alias for a longer URL. For the fork/clone development workflow a repository will be in one of three locations.
- On your local machine. A local clone on a developer's computer
- In your remote fork on github. The
originremote points to your fork in github, created automatically by the 'git clone` command. - In the remote organization on github.The
upstreamremote points to the main remote repository in github, manually created to point to the repository from which your fork was created.