how to achieve in php to if user1 visit site1 through url1 then open content1,and if user2 visit same site1 through url2 then open content2
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How to achieve in php to if user1 visit site1 through url1    
then open content1,and if user2  visit same site1 through    
url2 then open content2.  
Content1 and content2 are the forms for login.