In Torrus framework, RPN expressions are the superset of those
in RRDtool. See the rrdtool graph
manual at
<http://www.rrdtool.com/manual/rrdgraph.html>.
Pops two arguments from stack, and pushes 0 if the arguments are equal, and 1 otherwise.
These functions pop two arguments from stack, and push back the result of logical operation. Unlike C operators,
Pops one value from stack and pushes 0 if the argument is nonzero, otherwise 1.
Pops one value from stack and pushes the absolute value of it.
Pushes the current time, in seconds since Epoch.
Equivalent of %
, the modulo operator. In Torrus parameter value,
percent sign is reserved for parameter substitution.
Returns zero if the argument is undefined, and the argument's numeric value otherwise
Returns the positive or negative infinity.
In certain context, the values of the datasources can be evaluated into RPN expression.
The general format for data access is following:
{FUNC@PATH(-OFFSET)}
FUNC@
specifies a special function to be performed on the
data being accessed.
For monitor expressions, T@
returns the timestamp of the data source.
For rrd-cdef
leaf types and for rrd-multigraph
datasource types,
the following functions affect the graph shape: AVERAGE@
, MIN@
,
MAX@
, and LAST@
. They cause the corresponding Consolidation Function
being used when creating a graph.
PATH
specifies the relative name for the data source.
If omitted, the current leaf value is taken. If starts with /
,
the path is considered as absolute.
Path starting with letter denotes the child of the parent subtree.
Double dot (../
) in the beginning of the path is interpreted as
current parent's parent subtree.
(OFFSET)
determines the time reference, as described in rrdtool fetch
manual. In addition, the word LAST
refers to the latest data timestamp
available.
(OFFSET)
is currently supported in Monitor expressions only.
Copyright (c) 2002-2004 Stanislav Sinyagin <ssinyagin@yahoo.com>