2 - Raspberry PI Community Projects

The gnome-system-monitor and qps graphical tools are similar to top and they provide roughly
the same features.
TIP
Visual representations of
activity
For more visual (and entertaining) representations of a computer's activity,
one should investigate the lavaps, bubblemon and bubblefishymon packages.
lavaps displays running processes as the wax bubbles in a lava-lamp. bubblemon
is a desktop panel applet representing the amount of used memory and
the processor usage as an aquarium with bubbles. bubblefishymon is rather
similar, but it also adds fish representing network traffic (and even a duck).
14.3.2.2. History
Processor load, network traffic and free disk space are information that are constantly varying.
Keeping a history of their evolution is often useful in determining exactly how the computer is
used.
There are many dedicated tools for this task. Most can fetch data via SNMP (Simple Network
Management Protocol) in order to centralize this information. An added benefit is that this allows
fetching data from network elements that may not be general-purpose computers, such as
dedicated network routers or switches.
This book deals with Munin in some detail (see Section 12.4.1, “Setting Up Munin” (page 343))
as part of Chapter 12: “Advanced Administration” (page 298). Debian also provides a similar
tool, cacti. Its deployment is slightly more complex, since it is based solely on SNMP. Despite
having a web interface, grasping the concepts involved in configuration still requires some effort.
Reading the HTML documentation (/usr/share/doc/cacti/html/index.html) should
be considered a prerequisite.
ALTERNATIVE
mrtg
mrtg (in the similarly-named package) is an older tool. Despite some rough
edges, it can aggregate historical data and display them as graphs. It includes
a number of scripts dedicated to collecting the most commonly monitored
data such as processor load, network traffic, web page hits, and so on.
The mrtg-contrib and mrtgutils packages contain example scripts that can be
used directly.
14.3.3. Detecting Changes
Once the system is installed and configured, and barring security upgrades, there's usually no
reason for most of the files and directories to evolve, data excepted. It is therefore interesting
to make sure that files actually do not change: any unexpected change would therefore be
worth investigating. This section presents a few tools able to monitor files and to warn the
administrator when an unexpected change occurs (or simply to list such changes).
384 The Debian Administrator's Handbook