$ /usr/bin/tar -cz /opt/back | /usr/bin/ssh myname@remote.host.com 'dd of=/opt/rback/back.tar.gz'

##</code><code>##

my $tar = "/usr/bin/tar";
my $taropts = "-cz";
my $backupdir = "/opt/back";
my $ssh = "/usr/bin/ssh";
my $user = "myname";
my $remotehost = "remote.host.com";
my $remotedir = "/opt/rback";

my @args = ($tar, "$taropts", "$backupdir", "\|", $ssh, "$user\@$remotehost", "'dd of=$remotedir/back.tar.gz'");

system(@args) == 0 or die "System @args failed: $!\n";