Characters "+" and "-" can be used to include/exclude NIS user login
permissions and change login shell.
For example, to disallow a NIS user
testu to login to a client, modify /etc/passwd on the
client as follows:
-testu::::::
+::::::
To allow only NIS users mikes and ksmith to be able to login to the client host:
+mikes::::::
+ksmith::::::
+:*:::::/etc/NoShell
To change the login shell of user mikes for /bin/tcsh: