When contributors add to a project from different machines or operating systems, it may happen that they use different email addresses or names for this, which will fragment contributor lists and statistics.

Running git shortlog -sn to get a list of contributors and the number of commits by them could result in the following output:

Patrick Rothfuss 871
Elizabeth Moon 762
E. Moon 184
Rothfuss, Patrick 90

This fragmentation/disassociation may be adjusted by providing a plain text file .mailmap, containing email mappings.

All names and email addresses listed in one line will be associated to the first named entity respectively.

For the example above, a mapping could look like this:

Patrick Rothfuss <[email protected]> Rothfuss, Patrick <[email protected]>
Elizabeth Moon <[email protected]> E. Moon <[email protected]>

Once this file exists in the project's root, running git shortlog -sn again will result in a condensed list:

Patrick Rothfuss 961
Elizabeth Moon 946

Syntax

Remarks

A .mailmap file may be created in any text editor and is just a plain text file containing optional contributor names, primary email addresses, and their aliases. it has to be placed in the project's root, next to the .git directory.

Keep in mind that this just modifies the visual output of commands like git shortlog or git log --use-mailmap. This will not rewrite commit history or prevent commits with varying names and/or email addresses.

To prevent commits based on information such as email addresses, you should use git hooks (opens new window) instead.