hg-fast-export を Homebrew でインストール

プロジェクトリンク

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コマンドとエイリアス

• hg-fast-export.py
• hg-fast-export.sh
• hg-reset.py
• hg-reset.sh
• hg2git.py

プロジェクトの歴史

The project began as a set of Mercurial export scripts written by Rocco Rutte with help from Git and Mercurial community channels. The README says most `hg-*` scripts are MIT-licensed, while `hg-reset.py` is GPLv2 because it copies code from Mercurial; Frej Drejhammar is listed as the maintainer.

Its core design is intentionally streaming. The README says hg-fast-export does not require a two-pass mechanism or prior repository analysis; it feeds Mercurial changesets into `git-fast-import`, relying on Mercurial's append-only storage model and linear ordering of changesets already seen by the converter.

Over time the converter accumulated migration features around the hard parts of real repositories: author maps, branch and tag maps, default-branch renaming, non-UTF-8 metadata conversion, filename encoding overrides, content filters, Mercurial largefiles handling, Git LFS strategies, plugin hooks, and reset support for restarting from an earlier import state.

採用の歴史

hg-fast-export became one of the standard command-line answers to the Mercurial-to-Git migration problem. Its README points users to the GitHub issue tracker for support, documents Git for Windows bash as a known-working Windows environment, and notes that incremental imports are supported for tracking Mercurial repositories over time.

The package gained extra relevance during the wider migration away from Mercurial hosting toward Git hosting. The input package facts record Homebrew packaging, and the formula keeps the tool one install away for macOS and Linux users doing repository conversion work.

使われ方

The basic workflow is to create an empty Git repository, run `hg-fast-export.sh -r <local-hg-repo>`, then check out the imported branch. The README stresses that remote Mercurial repositories must first be cloned locally because the Mercurial API and remote access protocol do not allow hg-fast-export to operate directly over HTTP or SSH.

Complex migrations often add an authors map with `-A`, branch and tag maps with `-B` and `-T`, a default-branch name with `-M`, encoding flags, content filters, or plugins. Large repositories can use the bundled Git LFS import path to write LFS pointers during conversion rather than doing a separate full history rewrite afterward.

パッケージ好きにとっての重要性

For package nerds, hg-fast-export is a classic migration utility: small surface, sharp edges, and deep dependence on two VCS data models. It matters because repositories are historical artifacts; preserving their history during a VCS migration is not just a one-time command, it is a careful mapping of authors, branches, tags, encodings, large files, and naming rules.

It is also notable because it wraps Git's plumbing rather than reimplementing Git storage. That keeps the tool scriptable and packageable, but makes its limitations visible: no direct remote Mercurial import, branch-name collisions, unnamed heads, case-insensitive filesystem traps, and the need for explicit mapping files in messy histories.

タイムライン

• 2000s: The project originated as Mercurial export scripts by Rocco Rutte, with community input from Git and Mercurial channels.
• 2010s: The tool became a common path for Mercurial-to-Git conversions as Git hosting grew dominant.
• 2017: Older author-map syntax was kept behind `--mappings-are-raw` for compatibility with pre-v171002 behavior.
• 2020s: The project documented Python 3.7+ and Mercurial 5.2+ requirements and added migration features for largefiles, LFS, and plugins.
• Package-manager era: Homebrew packages the converter as `hg-fast-export` with wrapper scripts such as `hg-fast-export.sh` and `hg-reset.sh`.

Related projects

• hg-fast-export is related to Mercurial, Git, `git-fast-import`, Git LFS, hg-git, git-remote-hg, repository-host migration tooling, and batch converters such as Chris J Billington's `hg-export-tool`.

ソース

• https://formulae.brew.sh/formula/hg-fast-export
• https://github.com/frej/fast-export
• https://raw.githubusercontent.com/frej/fast-export/master/README.md
• https://repo.or.cz/w/fast-export.git