How to modify data on the linux terminal from java?

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http://askubuntu.com – I am creating a java software on linux ubuntu. I want to to open linux terminal from inside java, set commands to the terminal, execute the commands and then close the terminal. All these by clicking on a button in java. So in short, the user of my application will not need to know any linux commands. In fact my software consists of configuring linux ubuntu 12.04 as server from java. I want to open the dhcpd.conf file and change its contents based on the user's input, such as changing the pool of ip address based on the user's choice. Any help on how I can do this please? Thank you (HowTos)