Automagically merging ChangeLog files with mercurial or git

When a project keeps a GNU style ChangeLog file to keep track of who changed what where then those files can be automagically merged if you use mercurial or git.

gnulib contains a module git-merge-changelog which, despite the name, works perfectly with several version control systems.

To install it:

git clone git://
cd gnulib
./gnulib-tool --create-testdir --dir=/tmp/testdir123 git-merge-changelog
cd /tmp/testdir123
make install


For Mercurial add the following lines to your ~/.hgrc:

ChangeLog = git-merge-changelog

git-merge-changelog.executable = /usr/local/bin/git-merge-changelog
git-merge-changelog.args = $base $local $other

That installs the git-merge-changelog driver globally for all hg repos.


For git add the following lines to your ~/.gitconfig

[merge "merge-changelog"]
	name = GNU-style ChangeLog merge driver
	driver = /usr/local/bin/git-merge-changelog %O %A %B

    attributesfile = ~/.gitattributes

And add the following line to ~/.gitattributes

ChangeLog       merge=merge-changelog

Note: The global core.attributesfile exists only since git 1.7.4, before that you would have to configure this for each git repo separately, by doing:

cd ~/src/[repo-name]
echo "ChangeLog   merge=merge-changelog" >> .git/info/attributes

And never worry again about having to manually merge ChangeLog files.


  1. Kamil Páral says:

    There’s actually no point in having ChangeLog file anymore. Since the invention of VCS that file is useless.

    • Mark Wielaard says:

      Maybe, if commit message do contain the same information as the ChangeLog entries. Which isn’t the case in some projects. And sometimes sources are distributed separate from the VCS, then having a ChangeLog file is handy. There are also other tools to generate ChangeLog files from various CVS commit messages. But some projects do have ChangeLog files. And in that case having automatic ChangeLog entry merging is pretty convenient.