PHP is a popular general-purpose scripting language that is
especially suited to web development.
Fast, flexible and pragmatic, PHP powers everything from your blog to the largest social networking site in the world.
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The PECL/rrd extension provides bindings to the RRDtool C library.
RRDtool is the open source industry standard, high performance data
logging and graphing system for time series data.
The RRDtool homepage is » http://www.mrtg.org/rrdtool/.