Easy and fun
Things needed :
dstat
GNUPlot
This post, is not elaborating on dstat or GNUplot but rather focusing directly on how to plotting performance graph of a GNU/Linux box.

I have written a small script to plot the performance of the machine considering CPU,Memory and Network into picture.

#!/bin/bash
#Author : Hemanth H.M
#Licence : GNU GPLv3

# Usage
show_help(){
echo "Usage is $0 a|m|n|c|h"
echo "-a or --all to plot cpu(c),mem(m) and net(n)"
}

# Make directory to store the results
setdir(){
mkdir -p Stats
cd Stats
}

# Use dstat to get the data set
gendata(){
echo "Collecting stats for 60sec with an interval of 10sec"
dstat -tmnc 10 > dstat.dat&
[ "$?" -ne 0 ] && echo "Please check if you have installed dstat" && exit 1
sleep 60s
exec 2>/dev/null
kill $! >/dev/null 2>&1
#Remove the headers
sed '1,2d' dstat.dat > stat.dat
}
#############################################
MAIN BLOCK
#############################################
# Use GNU plot to plot the graph
graph (){
gnuplot << EOF
set terminal $fileType
set output $output
set title $title
set xlabel $xlabel
set xdata time
set ylabel $ylabel
set timefmt "%d-%m %H:%M:%S"
set format x "%H:%M"
plot ${plot[*]}
EOF
}

# Plot CPU usage
plotcpu(){
fileType="png"
output='"cpu.png"'
title='"cpu-usage"'
xlabel='"time"'
ylabel='"percent"'

# Using an arry presrving the '"quotes"' is very much nessary
plot=( '"stat.dat"' using 1:3 title '"system"' with lines,'"stat.dat"' using 1:2 title '"user"' with lines,'"stat.dat"' using 1:4 title '"idle"' with lines )

graph

}

# Plot memory usage
plotmem(){
fileType="png"
output='"memory.png"'
title='"memory-usage"'
xlabel='"time"'
ylabel='"size(Mb)"'

plot=( '"stat.dat"' using 1:8 title '"used"' with lines,'"stat.dat"' using 1:9 title '"buff"' with lines, '"stat.dat"' using 1:10 title '"cach"' with lines,'"stat.dat"' using 1:11 title '"free"' with lines )

graph "png" '"memo.png"' '"cpu-usage"' '"time"' '"percent"' $plot
}

# Plot network usage
plotnet(){
fileType="png"
output='"network.png"'
title='"network-usage"'
xlabel='"time"'
ylabel='"size(k)"'

plot=( '"stat.dat"' using 1:11 title '"sent"' with lines,'"stat.dat"' using 1:12 title '"recvd"' with lines )

graph

}

# Clean up all the collected stats
clean(){
echo "Cleaning"
cd Stats
rm -r *.dat
echo "Done!"
}

#Check for the first input if it's zero show help
[ -z $1 ] && show_help && exit 1;

# Set dir and gen data
setdir
gendata
#wait
#clean
# Loop for different options
while [[ $1 == -* ]]; do
case "$1" in
-h|--help|-\?) show_help; exit 0;;
-a|--all) plotcpu ; plotmem ; plotnet ; exit 0;;
-m|--mem) plotmem ; exit 0 ;;
-n|--net) plotnet ; exit 0 ;;
-c|--cpu) plotcpu ; exit 0 ;;
--) shift; break;;
-*) echo "invalid option: $1"; show_help; exit 1;;
esac
done

The above is attached as a file with this post, the inputs to this script can be a,m,n,c. That is all,memory,network and CPU respectively.

The script is pretty much self explanatory, the time and interval for stat collection can be changed in the script as per the user requirement, after running this script you will have a folder by name "Stats" which will have *.png images which would be the graphs of the system usage in the past sixty seconds.

Script inspiration :UK LinuxUsers