#!/usr/bin/perl -w
use strict;
 
sub one {
   while(1) {
       print "in sub one\n";
        sleep 1;
   }
}
 
sub two {
   while(1) {
       print "in sub two\n";
        sleep 1;
   }
}
 
my $pid;
 
if( $pid = fork ) {
        one();
} elsif ( defined $pid ) {
        two();
}