[ubuntu] find what app is on port 80

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http://ubuntuforums.org – so i have a install of ubuntu server with startx ubuntu desktop gui. I was trying out new software like, wamp, xammp and other software. and the few i didnt like it i moved the start icon to the trash. i accidentally deleted them all. then i found one i liked. ampps. i wanted to access its web panel. to cut to the chase another server was already running on port 80. how do i find what app is running on port 80 and remove it???? :) (Hardware)