You should stop using --author each time you commit, and instead configure an author with git config. Once you’ve done so, you can type git commit and the author will be pulled from your .gitconfig file.
If you want to give --author a name to use for authoring the commit, you need to use
bob <bob@example.com>
not just bob. If your author string doesn’t match the user <user@example.com> format, Git assumes you’ve given it a search pattern, and it will try to find commits with matching authors. It will use the first found commit’s user <user@example.com> as the author.