| commit | dee80940b123ad7006e0497391d8c160ae15ba1b | [log] [tgz] |
|---|---|---|
| author | Julia Evans <julia@jvns.ca> | Wed Nov 12 19:53:20 2025 +0000 |
| committer | Junio C Hamano <gitster@pobox.com> | Wed Nov 12 12:21:15 2025 -0800 |
| tree | adf3f3e4a398923f58c38fc51e91a2d50f287b46 | |
| parent | 5099f64a82ccc80f3c6567589bfeb5e9a1b9fd6b [diff] |
doc: add an explanation of Git's data model
Git very often uses the terms "object", "reference", or "index" in its
documentation.
However, it's hard to find a clear explanation of these terms and how
they relate to each other in the documentation. The closest candidates
currently are:
1. `gitglossary`. This makes a good effort, but it's an alphabetically
ordered dictionary and a dictionary is not a good way to learn
concepts. You have to jump around too much and it's not possible to
present the concepts in the order that they should be explained.
2. `gitcore-tutorial`. This explains how to use the "core" Git commands.
This is a nice document to have, but it's not necessary to learn how
`update-index` works to understand Git's data model, and we should
not be requiring users to learn how to use the "plumbing" commands
if they want to learn what the term "index" or "object" means.
3. `gitrepository-layout`. This is a great resource, but it includes a
lot of information about configuration and internal implementation
details which are not related to the data model. It also does
not explain how commits work.
The result of this is that Git users (even users who have been using
Git for 15+ years) struggle to read the documentation because they don't
know what the core terms mean, and it's not possible to add links
to help them learn more.
Add an explanation of Git's data model. Some choices I've made in
deciding what "core data model" means:
1. Omit pseudorefs like `FETCH_HEAD`, because it's not clear to me
if those are intended to be user facing or if they're more like
internal implementation details.
2. Don't talk about submodules other than by mentioning how they
relate to trees. This is because Git has a lot of special features,
and explaining how they all work exhaustively could quickly go
down a rabbit hole which would make this document less useful for
understanding Git's core behaviour.
3. Don't discuss the structure of a commit message
(first line, trailers etc).
4. Don't mention configuration.
5. Don't mention the `.git` directory, to avoid getting too much into
implementation details
Signed-off-by: Julia Evans <julia@jvns.ca>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.adoc to get started, then see Documentation/giteveryday.adoc for a useful minimum set of commands, and Documentation/git-<commandname>.adoc for documentation of each command. If git has been correctly installed, then the tutorial can also be read with man gittutorial or git help tutorial, and the documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.adoc (man gitcvs-migration or git help cvs-migration if git is installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission and Documentation/CodingGuidelines).
Those wishing to help with error message, usage and informational message string translations (localization l10) should see po/README.md (a po file is a Portable Object file that holds the translations).
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Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the “What's cooking” reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name “git” was given by Linus Torvalds when he wrote the very first version. He described the tool as “the stupid content tracker” and the name as (depending on your mood):