open ($archive_file_handel, '+<', $archive_file_spec) or die "Can't open $archive_file_spec: $!";

$first_line = <$archive_file_handel>;	# actually only line 

seek($archive_file_handel, 0, 2);		# works , appends to end
seek($archive_file_handel, 0, SEEK_END); # fails, writes to begining

print { $archive_file_handel } "another piece of data to go after header\n";	# Write out junk for now