How can we change value of $baseurl in joomla

Hi All,

I have 2 joomla sites, using one Database.

Lets say 1 parent site and the other one is child site.

Am using parent site’s DB for the child site.

Now i need all the links from my child site should point the parent site.

I noticed joomla is using $baseurl to get the path dynamicaly.

Can anyone help me how can i change the value of $baseurl.

Thanks in Advance.