Gnuplot Time Data Question

Shell Programming and Scripting
1

I have a data file of the following format:

servername,2013-05-11 17:46:03,SomeText,195,195,11,202 
servername,2013-05-11 17:47:03,SomeText,192,192,23,103 
servername,2013-05-11 17:48:03,SomeText,189,190,14,117 
servername,2013-05-11 17:49:03,SomeText,196,195,24,231 
... 
...

I want to plot a graph where the x-axis has the time (%H:%M:%S) values (don't need the date part. The y-axis should have the two last columns.

Here's a sample bash script I have to run this.

#!/usr/bin/bash 

basedir="app-stats" 
termsize="1200,600" 
xtics="1800" 
type="proc" 
range="*:" 

echo $server-$filenm.data 

gnuplot -persist << EOF 
reset 
set terminal pngcairo size ${termsize} enhanced font 'Verdana,8' 
set xdata time 
set timefmt "%Y/%m/%d %H:%M:%S'" 
set format x "%H:%M:%S" 
set datafile separator "," 
set xtics nomirror rotate 
set xtics ${xtics} 
set ytics nomirror 
set y2tics 
set grid xtics lt 0 lw 1 lc rgb "#000000" 
set grid ytics lt 0 lw 1 lc rgb "#880000" 
set grid y2tics lt 0 lw 1 lc rgb "#008800" 
set ylabel 'servername' 
set y2label 'proc' 
set auto fix 
set offsets graph 0, graph 0, graph 0.1, graph 0 
show offsets 
set title "App Statistics for ${host}" enhanced font 'Verdana Bold,10' 
set label "Date: 02/07/13" at screen 0.01, 0.97 
set label "SomeLabel" at screen 0.98, 0.97 right 
set key inside center bottom horizontal Right noreverse enhanced autotitles box linetype -1 linewidth 1.000 

set output "$server-$filenm.png" 
plot '$server-$filenm.data' using 1:6 title 'proc/s'  with lines lt rgbcolor "light-red" lw 2, \ 
     '$server-$filenm.data' using 1:7 axes x1y2 title 'cswch/s' with lines lt rgbcolor "blue" lw 2 
EOF 

exit

I can plot this successfully if the time data doesn't contain "date space time" but only time and the server name isn't the first field (see below).

17:46:03,SomeText,195,195,11,202 
17:47:03,SomeText,192,192,23,103 
... 
...

My questions are:

  1. Can I have a non-xdata column before the xdata column like "servername" and identify where the xdata column is in the "using (1:6)" statement, substituting 1:6 with say, 3:6 if the xdata column is the third column? I'm not able to get this to work.

  2. If the first column is

2013-05-11 17:46:03 , how can I get it to plot correctly using either

set timefmt "%Y/%m/%d %H:%M:%S'" 
set format x "%H:%M:%S"

or

set timefmt "%Y/%m/%d %H:%M:%S'" 
set format x "%Y/%m/%d %H:%M:%S"

Cheers,
Beery