why doesn't this shell program work

[Henry Spencer]

The pipe is causing the main shell to spin off a child shell to run
the innards of the for-loop.  The result is that the variable
is local to the child, and naturally doesn't propagate back into the
parent since there is no path by which it might do so.  You have just
encountered Excedrin Headache number 3.14159 for shell programmers.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry