untested

use strict;

my $file1 = shift(@ARGV);
my $file2 = shift(@ARGV);

# open the first file, slurp the contents into 
# $file1_contents
open(FILE1, "<", $file1) or die "Whoops!";
my $file1_contents = <FILE1>;
close(FILE1);

# open the second file in append mode, print
# the contents from file1 into file2
open(FILE2, ">>", $file2) or die "Whoops!";
print FILE2 $file1_contents;
close(FILE2);
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This is not tested so I may have screwed something up but the idea should work.