if ($pid[$i]=fork()) {   # parent process
    waitpid($pid[$i], 0);  # wait for child
    close ($wh);
    ...

##</code><code>##

##
## launch children
##
for( $i = 0 ; $i < NUMPROCS ; $i++ ) {
  $pid[$i] = fork() ;
  next if( $pid[$i] != 0 ) ; # fork next process
  ##
  ## child stuff
  ##
  exit(0) ; # when finished
}
##
## gather children
##
foreach( @pid ) {
   waitpid($_, 0) ; # waits for each child
   if( $? != SOMETHINGGOOD ) {
      # bad exit status
   }
}