How to hide many user accounts in login screen.

• I want to hide my several ubuntu account such as ftp, svn in login screen.
• (우분투 12.04 로그인 스크린에서 사용자 계정이 여러개가 존재할 때 계정을 안보이게 하는 방법)

1. You have to be root to perform this way.
   If you are not root then be root by executing following command.
   : sudo su -
2. Backup the original file by executing following command.
   : cp -p /etc/lightdm/lightdm.conf /etc/lightdm/lightdm.conf.orig
3. Open lightdm.conf by executing following command.
   : vi /etc/lightdm/lightdm.conf
4. Enter following line to [SeatDefaults] Selection: ~
   : greeter-hide-users=true
   
   * Example (your lightdm.conf should look like below)
     [SeatDefaults]
     greeter-session=unity-greeter
     user-session=ubuntu
     greeter-hide-users=true
5. Save the file and Exit
6. Reboot ubuntu 12.04

• Actually, the source of this post exist. However i did not remember source URL.