An Introduction to Network Simulator

AWK, GnuPlot

Dr. Ajit K NayakDept of CSIT, ITER

S‘O’A University, BBSR

Part III

• Introducing AWK

• Introducing gnuPlot

Basics of AWK • AWK is a scripting language suitable for text processing /

data extraction and report formatting.

• It is interpreted line by line and produces the output in a required format.

• Input text files are considered to be a set of records containing different fields, i.e. each line in the file is a record (row) and each word of a line is considered as a field (column).

• The default column separator is white space, however other delimiters such as a comma (,), or a tab space may also be used.

• First column of the file is accesses using $1, second column using $2 etc.

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Example-1• Let us consider a text file (file.txt) with the following content.

Ashok 20-sep-1991 India

Marry 13-oct-1995 Italy

John 15-mar-1990 USA

Karim 25-Feb-1993 Pakistan

• Command Line Execution:– Issue the following commands in the command prompt.

awk < file.txt ’{print $2}’

or

awk ’{print $2}’ file.txt

• It will display the second field(column) of each line available in a text file called ’file.txt’.

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General Structure of AWKBEGIN action(s)

A set of patterns action(s) pair

END action(s)

• All actions with BEGIN pattern are executed once at the beginning of the execution of the script. Normally the variable initializations are made in this section.

• The pattern-action pair between BEGIN and END pattern are executed for each line of the input file.

• Finally actions with END pattern are executed once at the end. END section is normally used for printing the summarized results.

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Example• Let us consider a text file (file.txt) with the following content.

1001 Ashok 83 73 93

1002 Ram 30 43 67

1003 John 45 69 83

1004 Marry 43 35 59

1005 Samita 20 33 47

1006 Shibani 66 66 76

1007 Sourav 30 25 45

1008 Samyak 71 75 65

1009 Rudra 30 43 67

1010 Laila 85 83 87

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Example-2 • Write AWK script to print All the students having first division

with their average % score of marks

#program to print student names scoring First division

BEGIN {

lines=0;

print "\n Students with First Division";

print "=========================";

}

{

lines++;

avg=($3+$4+$5)/3;

if (avg >= 60) {

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printf $2 "\t" avg "%\n";

}

}

END{

print “=====*=====";

print lines " lines scanned...";

}

Execute with: awk -f myFirstAwk.sh < file.txt

Practice Programs • Write and execute all example programs

• Write AWK script for the followings

– To print the list of Failed students.

– To print the list of Poor students.

( avg mark < class avg)

Data format: (reg, name m1, m2, m3)

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GNUPlot• GNUPlot is a software used to plot graphs using

data or functions.

• It is a command driven and suitable for 2D as well as 3D plots.

• To start, issue the command gnuplot in the command line, that will a result a prompt like,

gnuplot>

• This is called the gnuplot command line. A plot now can be created using any of the following two ways.

i) use the plot command in command line, or

ii) create a script file with extension ’<script_file>.p’ then load the script.

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Plotting • Plot using a predefined function:

gnuplot > plot sin(x)/x

• Plot using a data file (scheduling.dat)

# Processor requirement for different algorithms

#Tasks Alg1 Alg2 Alg3

70 5 8 10

80 6 10 11

90 7 12 12

100 10 14 15

plot “scheduling.dat" using 1:2 title ’Alg1’ with lines, \

“scheduling.dat" u 1:4 t ’Alg’ w linespointsNS-2/AN/Intro/ 10

#Task Alg1 Alg2 Alg3110 10 16 18

120 11 19 22

130 12 25 23

140 13 30 24

150 13 34 26

Customizing plots#Gnuplot script file: scheduling.p

set autoscale # scale axis automatically

set xtic auto # set xtics automatically

set ytic auto # set ytics automatically

set title "Processor requirement in different Algs"

set xlabel "Processors"

set ylabel "Tasks"

set key 0.01,100 #position of Legend

plot "scheduling.dat" u 1:2 t ’Alg1’ w lines , "scheduling.dat" u 1:3 t ’Alg2’ with linespoints

• To execute this script: gnuplot> load ’schedule.p’

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Histograms# File name: histo.p;

set grid;

set style data histograms;

set style histogram cluster;

set style fill pattern;

set key left;

plot ’scheduling.dat’ using 2:xtic(1) t “Alg1", \

"" u 3 t "Alg2", "" u 4 t "Alg3";

• The col1 data of the data file(scheduling.dat) is taken to be the values in the x-axis.

• The values in col_2 - col_4 forms three bars in a cluster.

• Each row of data file is treated as one cluster and numbers of bars in a cluster is the number of columns considered in the plot command.

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Practice Programs• Write and execute all example programs

• Consider the data file containing marks of the students in 3 subjects and plot the following graphs.

– Draw a line plot containing 3 lines i) regNo vs mark1, ii) regNo vs mark2, and iii) regNo vs mark3.

– A histogram that contains regNo in x axis and 3 different marks of one student is plotted as 3 clustered bars for each students.

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Output? (twoNode.tr)+ 1 0 1 cbr 500 ------- 0 0.0 1.0 0 0

- 1 0 1 cbr 500 ------- 0 0.0 1.0 0 0

+ 1.005 0 1 cbr 500 ------- 0 0.0 1.0 1 1

- 1.005 0 1 cbr 500 ------- 0 0.0 1.0 1 1

+ 1.01 0 1 cbr 500 ------- 0 0.0 1.0 2 2

- 1.01 0 1 cbr 500 ------- 0 0.0 1.0 2 2

r 1.014 0 1 cbr 500 ------- 0 0.0 1.0 0 0

+ 1.015 0 1 cbr 500 ------- 0 0.0 1.0 3 3

- 1.015 0 1 cbr 500 ------- 0 0.0 1.0 3 3

r 1.019 0 1 cbr 500 ------- 0 0.0 1.0 1 1

+ 1.02 0 1 cbr 500 ------- 0 0.0 1.0 4 4

- 1.02 0 1 cbr 500 ------- 0 0.0 1.0 4 4

r 1.024 0 1 cbr 500 ------- 0 0.0 1.0 2 2

Explaining Output (I)

• Column 1: events– +: enqueue– -: dequeue– r: receive– d: drop

• Column 2: – Time of event

• Column 3 & 4: – Trace between which two nodes?

Network Performance - IAverage Delay:

• It is the average of total delay incurred due to all packets.

– For each packet i received, find the delay asdelayi

= arrivalTimePacketi - sendingTimePacketi

– Compute Average delay for n packets as follows

avgDelay = 1..n delayi / n

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Network Performance - IINetwork Throughput:

• It is defined as the total number of bytes received at the destination per sec.

– Add the bytes of all data packets received.

– Divide the total size calculated in above step by the simulation time.

– To get the values in Mbps multiply final value with 8/1000000.

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AWK Script to find Packet Statistics#== =packetStat.awk ===

# Run with: awk -f packetStat.awk < trace.tr

BEGIN {

totPktRecvd=0

drop=0

}

{

event = $1

intDest = $4

if (event == "r" && intDest == dest) {

totPktRecvd ++

}

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AWK Script contd.if (event == "d") {

drop++

}

}

END {

printf("Total Packets Recvd = %g \n",totPktRecvd)

printf("Total Packets Dropped = %g \n",drop)

}

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AWK Script to compute Avg Delay#== =avgDelay.awk ===

# Run with: awk -f avgDelay.awk < trace.tr

BEGIN {

for (i in pktSent) {

pktSent[i] = 0

}

for (i in pktRecvd) {

pktRecvd[i] = 0

}

delay = avgDelay = 0

} # begin ends here

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Avg Delay script contd.{

event = $1

time = $2

intSrc=$3

intDest=$4

src=$9

dest=$10

pktSeq = $12

intSrc = (intSrc".0")

intDest = (intDest".0")

# Store packets send times

if (pktSent[pktSeq] == 0 && event == "+" && intSrc == src) {

pktSent[pktSeq] = time

} NS-2/AN/Intro/ 21

Avg Delay script contd. - I# Store packets arrival time

if (event == "r" && intDest == dest) {

pktRecvd[pktSeq] = time

}

}

END {

# Compute average delay

for (i in pktRecvd) {

if (pktSent[i] == 0) {

printf("\nError %g\n",i)

}

delay += pktRecvd[i] - pktSent[i]

num ++

} NS-2/AN/Intro/ 22

Avg Delay script contd. - IIif (num != 0) {

avgDelay = delay / num

} else {

avgDelay = 0

}

printf("Avg Delay = %g ms\n",avgDelay*1000)

} # program ends here

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Practice Programs

• Write a NS script to implement above programand generate a trace file (trace.tr)

• Write one AWK script to find packet statistics and average delay.

• Write one AWK script to find average network throughput

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Suggested Readings• The GNU Awk User's Guide

–http://www.gnu.org/software/gawk/ manual/gawk.html

• Official gnuplot documentation

–http://www.gnuplot.info/documentation.html

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Thank You

End of NS2