The following Korn shell function connects to a MySQL database and extracts specified data, which is then plotted as a function of time using GNUPlot.  Using correct syntax is critical. Note the use of single- and double-quotes.  In the example below, “using 2:4” mean that that the second column in your database table will be the X-axis values and the fourth column – the Y-axis value F(x). The graph below utilizes Bezier smoothing. This makes the chart look cleaner, but it may not be appropriate for your data.

GNUPlot_Update_Func() {

#------ Client Disk Allocation and Utilization vs. Time ------

$MYSQL --column-names=0 -u$DBUSER -p$DBPASS $DBNAME << EOF | while read HOSTNAME
SELECT DISTINCT host_name FROM sandisk_clients ORDER BY host_name;
EOF
do
$MYSQL --column-names=0 -u$DBUSER -p$DBPASS $DBNAME < "${TMPDIR}/${HOSTNAME}_gnuplot_client.dat"
SELECT host_name, line_datetime, SUM(alloc_kb), SUM(used_kb) 
FROM sandisk_clients 
WHERE host_name LIKE '$HOSTNAME'
GROUP BY YEAR(line_datetime), MONTH(line_datetime), DAYOFMONTH(line_datetime);
EOF
echo "set title '$HOSTNAME'"					 >  "${TMPDIR}/${HOSTNAME}_gnuplot_client.gnu"
echo "set xdata time"						>>  "${TMPDIR}/${HOSTNAME}_gnuplot_client.gnu"
echo "set key box"						>>  "${TMPDIR}/${HOSTNAME}_gnuplot_client.gnu"
echo "set key bottom right"					>>  "${TMPDIR}/${HOSTNAME}_gnuplot_client.gnu"
echo "set size 1.5,1.5"						>>  "${TMPDIR}/${HOSTNAME}_gnuplot_client.gnu"
echo "set xlabel 'Date'"					>>  "${TMPDIR}/${HOSTNAME}_gnuplot_client.gnu"
echo "set ylabel 'Size, Kb' font 'Arial,12'"			>>  "${TMPDIR}/${HOSTNAME}_gnuplot_client.gnu"
echo "set autoscale"						>>  "${TMPDIR}/${HOSTNAME}_gnuplot_client.gnu"
echo 'set timefmt "%Y-%m-%d %H-%M-%S"'				>>  "${TMPDIR}/${HOSTNAME}_gnuplot_client.gnu"
echo "set term png color"					>>  "${TMPDIR}/${HOSTNAME}_gnuplot_client.gnu"
echo "set output '${CHARDIR}/${HOSTNAME}_client_001.png'"	>>  "${TMPDIR}/${HOSTNAME}_gnuplot_client.gnu"
echo "plot '${TMPDIR}/${HOSTNAME}_gnuplot_client.dat' using 2:4 title 'Allocated, Kb' smooth bezier with
linespoints, '${TMPDIR}/${HOSTNAME}_gnuplot_client.dat' using 2:5 title 'Used, Kb' smooth bezier with linespoints" >>  "${TMPDIR}/${HOSTNAME}_gnuplot_client.gnu"

$GNUPLOT  /dev/null 2>&1
done
}