If the file handle came from a piped open "close"
               will additionally return false if one of the other
               system calls involved fails or if the program
               exits with non-zero status.  (If the only problem
               was that the program exited non-zero $! will be
               set to 0.)  Closing a pipe also waits for the pro-
               cess executing on the pipe to complete, in case
               you want to look at the output of the pipe after-
               wards, and implicitly puts the exit status value
               of that command into $?.