als shell kannst auch /sbin/nologin verwenden
aus der man page:
Code:
NAME
nologin - politely refuse a login
SYNOPSIS
nologin
DESCRIPTION
nologin displays a message that an account is not available and exits
non-zero. It is intended as a replacement shell field for accounts that
have been disabled.
If the file /etc/nologin.txt exists, nologin displays its contents to the
user instead of the default message.