Am 25.02.2013 um 19:35 schrieb john Culleton :

What is the difference between \environment foo.tex and \input foo.tex?

When you use \environment the file is only loaded once but \input load the file each time. When you try to load a file which doesn’t exist \input produces a error message and asks for a valid filename while \environment mentions an not existent file but doesn’t interrupt the compile process. Wolfgang