Git: replace commit author name and email on every commit that matches

gistfile1.txt

git filter-branch --env-filter '
    oldname="Cyril"
    oldemail="old.email@example.com"
    newname="Cyril Sadovnik"
    newemail="new.email@example.com"
    [ "$GIT_AUTHOR_EMAIL" = "$oldemail" ] && GIT_AUTHOR_EMAIL="$newemail"
    [ "$GIT_COMMITTER_EMAIL" = "$oldemail" ] && GIT_COMMITTER_EMAIL="$newemail"
    [ "$GIT_AUTHOR_NAME" = "$oldname" ] && GIT_AUTHOR_NAME="$newname"
    [ "$GIT_COMMITTER_NAME" = "$oldname" ] && GIT_COMMITTER_NAME="$newname"
    ' head