Git Describe: Ref-Based Human-Readable Names

Advanced

Learner goal

By the end of this lesson, you should be able to explain what `git describe` names, understand how Git selects candidate tags or refs, distinguish annotated-tag defaults from `--tags` and `--all`, interpret distance and abbreviated-object output, and use `--dirty` when reporting a working-tree state.

What `git describe` produces

`git describe` finds a name for an object by walking backward from that object and using a suitable ref, normally an annotated tag reachable from the target. When the target is not exactly at the selected tag, the result can contain the tag name, the number of commits since that tag, and an abbreviated object name.

git describe HEAD

Create an annotated tag before several commits.?git describe HEAD

Exact tag versus commits after a tag

If the target itself is exactly at the selected tag, the description can simply be the tag name. If commits have been added after the tag, Git reports the tag followed by the number of commits since it and an abbreviated object identifier for the target.

git describe release-1.0
git describe HEAD

The commit count is not a count of all commits in the repository. It describes the distance from the selected tag to the target under the traversal rules used by `git describe`.

Have an annotated tag followed by two commits.?git describe HEAD

Which tags are candidates?

By default, `git describe` considers annotated tags. `--tags` tells it to consider lightweight tags as well. This is different from the existing tag-creation lessons: the option changes which refs are eligible as naming candidates; it does not convert or modify any tag.

git describe HEAD
git describe --tags HEAD

Create both an annotated and a lightweight tag in a disposable repository.?Compare `git describe HEAD` with `git describe --tags HEAD`.

Using all refs with `--all`

`--all` tells `git describe` to use any ref found under `refs/`, rather than limiting candidates to tags. For example, a branch ref can become the descriptive name when it is the appropriate candidate.

git describe --all HEAD

This is a naming operation, not a claim that a branch is a release tag. The resulting name reflects the ref namespace Git selected.

Create a branch pointing at the target and inspect the description.?git describe --all HEAD

Reporting a dirty working tree

`--dirty` appends a dirty marker when the working tree has local modifications. This makes a generated version string distinguish a checked-out commit from the same commit when local working-tree changes are present.

git describe --tags --dirty

The marker reports working-tree dirtiness; it does not identify or summarize the modified files. Use status or diff commands when you need that separate information.

A precise workflow

When using `git describe` for a release or build identifier, first decide what object you are naming, then decide whether the default annotated-tag candidates are appropriate. Add `--tags` only when lightweight tags should participate, or `--all` when any ref may participate. Add `--dirty` only when the working-tree state belongs in the identifier.

git describe --tags --dirty HEAD

?

What this command does not do

`git describe` does not create, move, delete, or verify tags. It does not change commits or refs. It also does not replace `git status` or `git diff` when you need a detailed account of working-tree changes.

Practice what you learned

Use the dedicated Git code-completion exercise for this lesson.

Official source boundary

This lesson uses the official Git `git-describe` documentation and the official tag/ref model already established by the curriculum. No third-party documentation is used for command semantics.