#!/usr/local/bin/perl -lw
my $file = "test.txt";
unlink $file;
if(fork) {
    open STDOUT, ">>$file" or die "Can't write to file: $!";
    $| = 1;
    print "first";
    sleep 3;
    print "third";
} else {
    open STDOUT, ">>$file" or die "Can't write to file: $!";
    $| = 1;
    sleep 1;
    print "second";
}