I have a Mac running Mac OS 10.5.7. I want to set up a couple of SSH accounts for git usage. The accounts were initially configured with a home directory of /dev/null and a login shell of /usr/bin/false. In this setup, the accounts are not shown on the login screen or the fast user switching dropdown. However, in order for them to work with git, I needed to change their login shell to /opt/local/bin/git-shell. Once that change was made, they suddenly appeared on the login screen and the user dropdown. Is it possible to prevent these accounts from showing up in these lists?
To hide a user:
If you create the users with a sub 500 UID it's possible to hide any user with a UID less than 500 on the Login Window by running:
sudo defaults write /Library/Preferences/com.apple.loginwindow Hide500Users -boolean true
Add the user to the HiddenUserList by running
sudo defaults write /Library/Preferences/com.apple.loginwindow HiddenUsersList -array $USERNAME
There is a guide available at MacOSXHints.
Have a look at gitosis.