Shell tips in Linux

1. when you want to change hostname in Ubuntu , 
 # gksudo gedit /etc/hostname  => change name
 # gksudo gedit /etc/hosts         => change 127.0.0.1 hostname here

2. how to grant su privilege to a certain user
#  sudo vi /etc/sudoers

hduser ALL=(ALL:ALL) ALL

3. how to add PATH within profile
# vi .bashrc
 export PATH=$PATH:/home/jechul/Downloads/jdk1.6.0_27/bin