If you have bash-completion installed, several YaST modules can be started by
typing
    yast2 $module <tab><tab>
without pressing return.

Background: when pressing <tab><tab>, bash completion runs   
yast2 $module --help   in the background to find out which commandline options
are available.


Affected modules:

a) modules that simply get started by   yast2 $module --help
alternatives
auth-client
fonts
journal
krb-server
ldapkrb
ldap-server
partitioner 
virt-install
vpn

b) modules that show a window for a second and then print the help (wrong order
in the code):
users
samba-client
samba-server

c) special case
nis - asks to install the "ypbind" package, then exits and prints the help.
Also a case of wrong order in the code.


I don't have all YaST modules installed, therefore I'd recommend that 
you test yourself:

for mod in `yast2 -l | sed 1d` ; do 
    echo === trying $mod
    yast2 $mod --help
    echo === done $mod
    echo
done


Each module should at least have enough commandline handling to print
    This YaST2 module does not support the command line interface.
(Ideally using exactly this text, because it's already translated.)