screen size in the environment

[Adam Myrow]

I'm not sure why those variables aren't available to C programs, but they 
are apparently set by the OS.  This is fairly traditional in the Unix 
world.  The man page for ls in many versions of Unix (including Linux,) 
states that ls determines how wide to make its output from the variable 
COLUMNS.  If it is unset, ls assumes 80.  So, there is a good reason why 
the OS sets these somewhere.  As I said, I don't know why they don't show 
up with the C programs.