go

README

gitcalver

A Go implementation of GitCalVer, which derives calendar-based version numbers from git history.

Each commit on the default branch gets a unique, strictly increasing version of the form YYYYMMDD.N, where N is the number of commits on that UTC date.

See the GitCalVer specification for full details.

Installation

No external dependencies are required; git history is read directly using go-git.

go install gitcalver.org/go/cmd/gitcalver@latest

Or build from source:

make build

A container image is also available. Mount the repository at /repo:

docker run --rm -v "$PWD:/repo" gitcalver

Usage

gitcalver [OPTIONS] [REVISION | VERSION]

With no arguments, outputs the version for HEAD:

$ gitcalver
20260411.3

Version prefix

Use --prefix to prepend a string to the version number, e.g.:

Use case	Command	Example output
Default	gitcalver	20260411.3
SemVer	gitcalver --prefix "0."	0.20260411.3
Go	gitcalver --prefix "v0."	v0.20260411.3

Dirty workspace

By default, gitcalver exits with status 2 if the workspace has uncommitted changes. Use --dirty STRING to produce a version instead; the output will include the given string and a short commit hash (e.g. --dirty "-dirty" produces 20260411.3-dirty.abc1234).

Use --no-dirty-hash with --dirty to suppress the hash suffix. Use --no-dirty to explicitly refuse dirty versions (overrides --dirty).

Dirty versions are a convenience and are not necessarily unique.

Reverse lookup

Pass a version number instead of a revision to get the corresponding commit hash:

$ gitcalver 20260411.3
a1b2c3d4e5f6...

$ gitcalver --short --prefix "0." 0.20260411.3
a1b2c3d

If the version was generated with --prefix, pass the same --prefix for reverse lookup.

Dirty versions cannot be reversed.

Options

Option	Description
--prefix PREFIX	Literal string prepended to version
--dirty STRING	Enable dirty versions; append STRING.HASH
--no-dirty	Refuse dirty versions (overrides --dirty)
--no-dirty-hash	Suppress .HASH suffix (requires --dirty)
--branch BRANCH	Base branch name (e.g. main); overrides auto-detection. This is the branch versions are minted on, not the branch you are working on.
--short	Output short commit hash (reverse lookup mode)
--help	Show help

Exit codes

Code	Meaning
0	Success
1	Error (not a git repo, no commits, non-monotonic dates, shallow clone)
2	Dirty workspace or off default branch (without --dirty)
3	Cannot trace to default branch