use strict;
use warnings;

my $FILE = "/tmp/foo";

{ open my $fh, ">", $FILE or die; print {$fh} "Fnord\n" }

print "Contents =\n****\n", file_contents(), "****\n";
{ open my $fh, '>>', $FILE or die $!; print {$fh} "Plugh\n" }
print "Contents =\n****\n", file_contents(), "****\n";
print "Contents =\n****\n", file_contents(), "****\n";

sub file_contents
{
  local @ARGV = $FILE;
  local $/;
  my $contents = <>;
  return $contents;
}

##</code><code>##

Contents =
****
Fnord
****
Contents =
****
Plugh
****
Contents =
****
Fnord
Plugh
****