my $file = 'c:/test.txt';
# undef $/ to read whole file in in one go
undef $/;
open FILE, $file or die "Can't open $file $!\n";
# binmode FILE to supress conversion of line endings
binmode FILE;
my $data = <FILE>;
close FILE;
# convert data to hex form
my $hex = unpack 'H*', $data;
print $hex;

__END__
4a75737420416e6f74686572205065726c204861636b65720d0a