💡 Today I Learned

Convert a mercurial repo to git

The following is based on the technique from here: https://stackoverflow.com/a/39906349 and it is relevant because it retains more than 1 branch.

Further down I'll document a [simpler process] for when you're not concerned with branches.

The process (for us) is:

pre-requisites

  1. Make sure you have git installed. https://git-scm.com/downloads - click on windows

    Use the default options. But you may want a different editor for commit message than vim.

Steps

In the repo you wish to migrate:

  1. Add these to your mercurial.ini:

    [git]
branch_bookmark_suffix=_bookmark

[extensions]
hggit =

  2. check that hggit is recognised by running hg help; expect to see this under "enabled extensions":

    hggit push and pull from a Git server

  3. create a bookmark called "master" to represent the "default" branch

    hg bookmarks -r default master

...we do that because

> hg-git does not convert between Mercurial named branches and git branches as the two are conceptually different; instead, it uses Mercurial bookmarks to represent the concept of a git branch<br />
> &mdash;[Hg-Git Mercurial Plugin readme](https://github.com/schacon/hg-git#gitbranch_bookmark_suffix)

  1. for each branch (found via hg branches) run this command:

    hg bookmarks -r my_branch my_branch_bookmark

    (... but replacing my_branch with the name of your branch.)

Those mercurial bookmarks will be turned into branches in git.

You're now ready to create the git repo. 😄

  1. Create it like so:

    hg gexport

There will now be a folder called git under the .hg folder.

This is a "bare" repo.

You can clone it in git, or can follow a few steps to turn it into a "non-bare" repo.

To convert a --bare repository to a non-bare:

Make a .git folder in the top-level of your intended new repository location.

Copy the contents of the git bare repository into the .git folder you just created. i.e. copy the repository management things (HEAD branches config description hooks info objects refs etc.) into your new folder.

Run:

git config --local --bool core.bare false

...to convert the local git-repository to non-bare.

Stare and compare that the new git repo matches the old hg repo, until you are completely satisfied.

Sources

See also