git filter-branch -f --commit-filter '
      if [ "$GIT_AUTHOR_NAME" = "old name" ];
      then
              GIT_AUTHOR_NAME="new name";
              GIT_AUTHOR_EMAIL="new mail";
               GIT_COMMITTER_NAME="$GIT_AUTHOR_NAME";
               GIT_COMMITTER_EMAIL="$GIT_AUTHOR_EMAIL";
              git commit-tree "$@";
      else
              git commit-tree "$@";
      fi' HEAD