=head1 NAME

rrdinfo - extract header information from an RRD

=head1 SYNOPSIS

B<rrdtool> B<info> I<filename>
S<[B<--daemon>|B<-d> I<address> [B<--noflush>|B<-F>]]>

=head1 DESCRIPTION

The B<info> function prints the header information from an RRD in
a parsing friendly format.

Check L<rrdcreate> if you are uncertain about the meaning of the
individual keys.

=over 8

=item I<filename>

The name of the B<RRD> you want to examine.

=item B<--daemon>|B<-d> I<address>

Address of the L<rrdcached> daemon. If specified, a C<flush> command is sent
to the server before reading the RRD files. This allows B<rrdtool> to return
fresh data even if the daemon is configured to cache values for a long time.
For a list of accepted formats, see the B<-l> option in the L<rrdcached> manual.

 rrdtool info --daemon unix:/var/run/rrdcached.sock /var/lib/rrd/foo.rrd

=item B<--noflush>|B<-F>

Omit the C<flush> command usually sent to the daemon prior to retrieving the
data.  If all you are interested in is the RRD structure, and not the last update
time or current values, then this will improve efficiency.

=back

=head1 EXAMPLE

This is the output generated by running B<info> on a simple RRD which
contains two data sources and one RRA. Note that the number after the
I<last_update> keyword is in seconds since 1970. The string B<NaN>
stands for I<*UNKNOWN*> data. In the example it means that this RRD
has neither minimum nor maximum values defined for either of its
data sources.

 filename = "random.rrd"
 rrd_version = "0001"
 step = 300
 last_update = 955892996
 header_size = 2872
 ds[a].type = "GAUGE"
 ds[a].minimal_heartbeat = 600
 ds[a].min = NaN
 ds[a].max = NaN
 ds[a].last_ds = "UNKN"
 ds[a].value = 2.1824421548e+04
 ds[a].unknown_sec = 0
 ds[b].type = "GAUGE"
 ds[b].minimal_heartbeat = 600
 ds[b].min = NaN
 ds[b].max = NaN
 ds[b].last_ds = "UNKN"
 ds[b].value = 3.9620838224e+03
 ds[b].unknown_sec = 0
 rra[0].cf = "AVERAGE"
 rra[0].pdp_per_row = 1
 rra[0].cdp_prep[0].value = nan
 rra[0].cdp_prep[0].unknown_datapoints = 0
 rra[0].cdp_prep[1].value = nan
 rra[0].cdp_prep[1].unknown_datapoints = 0

=head1 ENVIRONMENT VARIABLES

The following environment variables may be used to change the behavior of
C<rrdtoolE<nbsp>info>:

=over 4

=item B<RRDCACHED_ADDRESS>

If this environment variable is set it will have the same effect as specifying
the C<--daemon> option on the command line. If both are present, the command
line argument takes precedence.

=back

=head1 AUTHOR

Tobias Oetiker E<lt>tobi@oetiker.chE<gt>

