I have run this command with root:
[root@localhost git-shell-commands]# ssh git@192.168.1.12
git@192.168.1.12's password:
Last login: Wed Jun 20 15:08:26 2012 from new-host.home
fatal: Interactive git shell is not enabled.
hint: ~/git-shell-commands should exist and have read and execute access.
Connection to 192.168.1.12 closed.
[root@localhost git-shell-commands]#
Anybody could told how to solve that problem?
git help shell gives some pointers on how to set it up. The hint in the output also. The git user need a subdirectory called git-shell-commands in its home directory, with appropriate permissions, and populated with the things you want the user to be able to run.