B<rrdtool> {B<update> | B<updatev>} I<filename>
S<[B<--template>|B<-t> I<ds-name>[B<:>I<ds-name>]...]>
-S<[B<--daemon> I<address>]>
+S<[B<--daemon> I<address>]> [B<-->]
S<B<N>|I<timestamp>B<:>I<value>[B<:>I<value>...]>
S<I<at-timestamp>B<@>I<value>[B<:>I<value>...]>
S<[I<timestamp>B<:>I<value>[B<:>I<value>...] ...]>
If given, B<RRDTool> will try to connect to the caching daemon L<rrdcached>
at I<address> and will fail if the connection cannot be established. If the
connection is successfully established the values will be sent to the daemon
-instead of accessing the files directly. If I<address> begins with C<unix:>
-then everything after this prefix will be considered to be a UNIX domain
-socket, see L<EXAMPLES> below. Otherwise the address is interpreted as network
-address or node name as understood by L<getaddrinfo>. One practical
-consequence is that both, IPv4 and IPv6, may be used if the system supports
-it. This option is available for the B<update> command only.
+instead of accessing the files directly.
+
+For a list of accepted formats, see the B<-l> option in the L<rrdcached> manual.
=item B<N>|I<timestamp>B<:>I<value>[B<:>I<value>...]
working with data-sources of type B<COUNTER>, B<DERIVE> or
B<ABSOLUTE>.
+When using negative time values, options and data have to be separated
+by two dashes (B<-->), else the time value would be parsed as an option.
+See below for an example.
+
+When using negative time values, options and data have to be separated
+by two dashes (B<-->), else the time value would be parsed as an option.
+See below for an example.
+
The remaining elements of the argument are DS updates. The order of
this list is the same as the order the data sources were defined in
the RRA. If there is no data for a certain data-source, the letter
=item *
+C<rrdtool update demo3.rrd -- -5:21 N:42>
+
+Update the database file demo3.rrd two times, using five seconds in the
+past and the current time as the update times.
+
+=item *
+
C<rrdtool update --cache /var/lib/rrd/demo3.rrd N:42>
Update the file C</var/lib/rrd/demo3.rrd> with a single data source, using the