Retroactively Correct Authors with Git SVN?

Start out by seeing what you've got to clean up:

git shortlog -s

For each one of those names, create an entry in a script that looks like this (assuming you want all the authors and committers to be the same):

#!/bin/sh

git filter-branch --env-filter '

n=$GIT_AUTHOR_NAME
m=$GIT_AUTHOR_EMAIL

case ${GIT_AUTHOR_NAME} in
        user1) n="User One" ; m="[email protected]" ;;
        "User Two") n="User Two" ; m="[email protected]" ;;
esac

export GIT_AUTHOR_NAME="$n"
export GIT_AUTHOR_EMAIL="$m"
export GIT_COMMITTER_NAME="$n"
export GIT_COMMITTER_EMAIL="$m"
'

That's basically the script I used for a large rewrite recently that was very much as you described (except I had large numbers of authors).

edit Use π pointed out a quoting problem in my script. Thanks!

You probably want to look into git-filter-branch, specifically the --commit-filter option. This command is a powerful chainsaw that can rewrite your entire repository history, changing whatever you might want to change.

Note that when you do this, you should pull new clones from the updated repository since the SHA1 hashes of every commit may have changed.

git filter-branch can be used to rewrite large chunks of history.

In this case, you would probably do something like (totally untested):

git filter-branch --env-filter '
    GIT_AUTHOR_NAME=`echo "${GIT_AUTHOR_NAME}" | sed -e "s/svnname1/Right Name/; s/svnname2/Correct Name/"`
    GIT_COMMITTER_NAME=`echo "${GIT_COMMITTER_NAME}" | sed -e "s/svnname1/Right Name/; s/svnname2/Correct Name/"`
    GIT_AUTHOR_EMAIL=`echo "${GIT_AUTHOR_EMAIL}" | sed -e "s/svnname1/[email protected]/; s/svnname2/[email protected]/"`
    GIT_COMMITTER_EMAIL=`echo "${GIT_COMMITTER_EMAIL}" | sed -e "s/svnname1/[email protected]/; s/svnname2/[email protected]/"`
'

As always, the following applies: in order to rewrite history, you need a conspiracy.