Basic Steps in Ubuntu 12.10

CLASSPATH SETTING IN UBUNTU

sudo gedit etc/environment

enter your password
PATH=".:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games" (already exist)
just add below two lines 

here i am using java6

JAVA_HOME="/usr/lib/jvm/java-6-openjdk"

CLASSPATH=".:/usr/lib/jvm/java-6-openjdk/lib"

 Disable Guest Session and the Remote login in UBUNTU

To disable the guest session and/or remote logon in Ubuntu 12.10 (Quantal Quetzal):

1. Open a terminal window.
2. Type “sudo nano /etc/lightdm/lightdm.conf”
3. Type in your sudo password.
4. Add the following in a new line at the end of the file if you want to disable the guest session: allow-guest=false
5. Add the following in a new line at the end of the file if you want to disable the remote login option: greeter-show-remote-login=false
6. If you choose to disable both, your lightdm.conf file should probably look like this:
[SeatDefaults]
greeter-session=unity-greeter
user-session=ubuntu
allow-guest=false
greeter-show-remote-login=false

7. Hit CTRL-X to exit nano.
8. Hit Y to save the file.
9. Hit Enter to accept the original filename and overwrite the file.
10. On the terminal, type “sudo restart lightdm” to restart the display manager. Doing so will require you to log in again and may close running apps, so save your work before doing so.
11. The guest session and/or remote logon options should now be disabled.