reposurgeon [command…​]


The purpose of reposurgeon is to enable risky operations that VCSes (version-control systems) don’t want to let you do, such as (a) editing past comments and metadata, (b) excising commits, (c) coalescing and splitting commits, (d) removing files and subtrees from repo history, (e) merging or grafting two or more repos, and (f) cutting a repo in two by cutting a parent-child link, preserving the branch structure of both child repos.

A major use of reposurgeon is to assist a human operator to perform higher-quality conversions among version control systems than can be achieved with fully automated converters.

The original motivation for reposurgeon was to clean up artifacts created by repository conversions. It was foreseen that the tool would also have applications when code needs to be removed from repositories for legal or policy reasons.

To keep reposurgeon simple and flexible, it normally does not do its own repository reading and writing. Instead, it relies on being able to parse and emit the command streams created by git-fast-export and read by git-fast-import. This means that it can be used on any version-control system that has both fast-export and fast-import utilities. The git-import stream format also implicitly defines a common language of primitive operations for reposurgeon to speak.

Fully supported systems (those for which reposurgeon can both read and write repositories) include git, hg, bzr, brz, darcs, bk, RCS, and SRC. For a complete list, with dependencies and technical notes, type "prefer" to the reposurgeon prompt.

Writing to the file-oriented systems RCS and SRC is done via rcs-fast-import(1) and has some serious limitations because those systems cannot represent all the metadata in a git-fast-export stream. Consult that tool’s documentation for details and partial workarounds.

Fossil repository files can be read in using the --format=fossil option of the ‘read’ command and written out with the --format=fossil option of the ‘write’. Ignore patterns are not translated in either direction.

SVN and CVS are supported for read only, not write. For CVS, reposurgeon must be run from within a repository directory (that is, a tree of CVS masters; a CVSROOT is not required). When reading from a CVS top-level directory each module becomes a subdirectory in the reposurgeon representation of the change history. It is also possible to read a repository from within a CVS module subdirectory and lift that individual module.

In order to deal with version-control systems that do not have fast-export equivalents, reposurgeon can also host extractor code that reads repositories directly. For each version-control system supported through an extractor, reposurgeon uses a small amount of knowledge about the system’s command-line tools to (in effect) replay repository history into an input stream internally. Repositories under systems supported through extractors can be read by reposurgeon, but not modified by it. In particular, reposurgeon can be used to move a repository history from any VCS supported by an extractor to any VCS supported by a normal importer/exporter pair.

Mercurial repository reading is implemented with an extractor class; writing is handled with hg-git-fast-import. A test extractor exists for git, but is normally disabled in favor of the regular exporter.

For details on how to operate reposurgeon, see the Repository Editing and Conversion With Reposurgeon.


reposurgeon relies on importers and exporters asociated with the VCSes it supports.


Core git supports both export and import.


Requires bzr plus the bzr-fast-import plugin.


Requires brz.


Requires core hg and hg-git-fast-import.


Stock Subversion commands support export and import.


Stock darcs commands support export.


Requires cvs-fast-export. Note that the quality of CVS lifts may be poor, with individual lifts requiring serious hand-hacking. This is due to inherent problems with CVS’s file-oriented model.


Requires cvs-fast-export (yes, that’s not a typo; cvs-fast-export handles RCS collections as well). The caveat for CVS applies.


Requires cvs-fast-export and sccs2rcs, the latter to do a lossless conversion to RCS. The caveat for CVS applies.


Versions 7.3 and after have a fast-export command that reposurgeon can use.


Returns 1 if the last command executed threw an error, 0 otherwise.


bzr(1), brz(1), cvs(1), darcs(1), git(1), hg(1), sscs(1), rcs(1), src(1), svn(1), bk(1).


Eric S. Raymond <>; see the project page.