I want to buy a web hosting business that already has customers , but I'm not sure what skills and knowledge are needed .

I own several websites and know basic knowledge about uploading a website , URL's , and know that the server space has to be leased and resold to customers according to their bandwidth and size of site .

However, Do I need to know Unix , Linux , or Perl or other programming languages ? If so , can this be out sourced reasonably ?

system admininstration/php/mysql knowledge/network security/network monitoring. If you do not know any of these you may want to hire a web developer for a month or two. Check websites like http://definitivelab.com/