Is it possible to get git to prompt only for a password, and determine your username automatically? I want to have the extra layer of manual intervention as a reminder to be careful what I push, but just entering a password and not also the username every time is sufficient.
If you are using https url, you can change said url in order to include your username just before the git repos hosting server (here, for instance, github.com):
git remote set-url origin https://<yourUsername>@github.com/<yourUsername>/<yourRepo>
^^^^^^^^^^^^^^
Each time you will git push, it will ask only for your password.