popen understood -- thanks

[T.C. Zhao]

Thanks to:

J. Lee         <jlee at sobeco.com>
Ron Quinn      <rjq at mpccl.ksu.edu>
Barry Margolin <barmar at Think.COM>
Dave Eisen     <dkeisen at leland.stanford.edu>

broken pipe is supposed to terminate the program if signal
SIGPIPE is not caught or ignored. For my aplication, a
signal(SIGPIPE,SIG_IGN) with error checks on the returns of i/o 
operation works fine.