`last.pl $source`;

#in last.pl

my $source = $ARGV[0];

##</code><code>##

$ENV{SOURCE} = $source;
`last.pl`;
#in last.pl
my $source = $ENV{SOURCE};

##</code><code>##

open(LAST, "|last.pl") or die $!;
print LAST "$source";
close LAST;

#in last.pl
$source = <STDIN>;