Notes

.
Practical: - 2
AIM: -STUDY OF UNIX COMMANDS
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PROGRAM:
2006 cd ~
2007 ls
2008 ls -l
2009 ls -a
2010 ls -r
2011 man ls
2012 echo "An Amazing Day" 2013 echo "An nAmazing Day" 2014 echo -e "An nAmazing Day"
2015 echo -e "An tAmazing Day" 2016 echo -e "An bAmazing Day" 2017 cal -1
2018 cal -3
2019 cal -s
2020 cal -m
2021 cal
2022 cal -j
2023 cal -y
2024 date +%a
2025 date +%A
2026 date +%b
2027 date +%B
2028 date +%Y
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2029 date +%w
2030 date +%d
2031 date +%m
2032 date +%y
2033 date +%T
2034 date +%H
2035 date +%M
2036 date +%S
2037 date +%V
2038 date +%P
2039 cat > file1.txt
2040 cat file1.txt
2041 cat file1.txt > file2.txt 2042 cat file2.txt
2043 cat file1.txt file2.txt
2044 cat file1.txt file2.txt > file3.txt 2045 cat file3.txt
2046 passwd
2047 who
2048 who -b
2049 who -H
2050 who -q
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2051 who -a
2052 whoami
2053 whoami --version
2054 uname -s
2055 uname -n
2056 uname -v
2057 uname -m
2058 uname -o
2059 ls
2060 mkdir temp 2061 ls
2062 mkdir -v temp2 2063 ls
2064 ls -l
2065 mv file1.txt ../temp 2066 mv file1.txt ../temp2 2067 mv file1.txt ../temp 2068 ls
2069 cat file1.txt
2070 cut -c 3 file1.txt
2071 cut -c 3-4 file1.txt
2072 cmp -b file1.txt file2.txt 2073 cmp -s file1.txt file2.txt 2074 cat file3.txt
2075 chmod 764 file3.txt 2076 ls -l
2077 file -i file1.txt
2078 finger root
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2079 sudo apt install finger 2080 finger root
2081 finger -m
2082 finger -l
2083 sleep 5
2084 sleep 6
2085 ps -e
2086 ps -x
2087 ps -f
2088 ps
2089 cat file2.txt
2090 wc file2.txt
2091 nl file1.txt
2092 sort file1.txt
2093 ls
2094 find file1.txt
2095 find file*
2096 find -newer file1.txt 2097 ls
2098 cat file1.txt
2099 grep hi file1.txt
2100 grep hello file1.txt
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2101 history
2102 history -40
2103 history -4
2104 history 4
2105 history 40
2106 history 50
2107 history 70
2108 history 100
2109 history 120
2110 history 110
2111 clear
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Practical: - 3
AIM: -IMPLEMENTATION OF SHELL SCRIPT
Implement following with shell script:
1. Write a shell script to input two numbers from the user and perform addition,
subtraction, multiplication, and division.
2.
The distance between two cities (in km.) is input through the keyboard.
Write a shell script to convert and print distance in meters, feet,
inches and centimeters.
3. Any integer is input through the keyboard. Write a shell script to find out whether it
is an odd number or even number.
4.
Write a shell script which receives any year form the keyboard and
determines whether the year is a leap year or not. If no argument is
supplied the current year should be assumed.
5. Write a shell script to find the factorial of any no entered through keyboard
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1.Write a shell script to input two numbers from the user and perform
addition, subtraction, multiplication, and division.
Code
#!bin/bash
echo "Enter Two
numbers: " read a
read b
echo "Enter
Choice: " echo
"1. Addition"
echo "2. Subtraction"
echo "3. Multiplication"
echo "4.
Division" read
ch
case $ch in
· ans=`echo $a + $b | bc`
;;
· ans=`echo $a - $b | bc`
;;
· ans=`echo $a * $b | bc`
;;
· ans=`echo "scale=2; $a / $b" | bc`
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;;
esac
echo "Result: $ans"
Output
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1. The distance between two cities (in km.) is input through the
keyboard.Write a shell script to convert and print distance in meters,
feet,inches and centimeters.
Code
#!bin/bash
echo "Enter distance between two cities
(in km.) : " read km
meter=`echo $km * 1000 |
bc` feet=`echo $meter *
3.2808 | bc` inches=`echo
$feet * 12 | bc` cm=`echo
$feet * 30.48 | bc`
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echo "Total meter is :
$meter " echo "Total feet
is : $feet" echo "Total
inches is : $inches" echo
"Total centimeters : $cm"
Output
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2. Any integer is input through the keyboard. Write a shell script to find out
whether it is an odd number or even number.
Code
Output
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3. Write a shell script which receives any year form the keyboard
anddetermines whether the year is a leap year or not. If no argument issupplied
the current year should be assumed.
echo "Enter a
year:" read year
if [ -z "$year" ]; then
year=$(date +"%Y")
fi
if [ $(( year % 4 ))
-eq 0 ] then
if [ $(( year % 100 ))
-eq 0 ] then
if [ $(( year % 400))
-eq 0 ] then
echo "$year is a leap year"
else
echo "$year is not a leap year"
fi
else
echo "$year is a leap year"
fi
else
echo "$year is not a leap year"
fi
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Output
4. Write a shell script to find the factorial of any no entered through
keyboard
Code
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Output
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Practical: - 4
AIM: -IMPLEMENTATION OF SHELL SCRIPT
1 Write a shell script which will accept a number band display first n prime numbers as
output.
2 Write a shell script which will generate first n Fibonacci numbers like: 1, 1, 2, 3, 5,
13,...
3 Write a shell script to read n numbers as command arguments and sort them in
descending order. Knowledge of
4 Write a shell script to display all executable files, directories and zero sized files.
5 Write a shell script to fetch data from a file and display data into another file in
reverse order.
1. Write a shell script which will accept a number band display first
n prime numbers as output.
Code
echo "Enter a
limit" read
limit
echo "prime numbers upto
$limit are :" echo "1"
i=2
while [ $i -le
$limit ] do
flag=1
j=2
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while [ $j -lt
$i ] do
rem=$(( $i %
$j )) if [ $rem
-eq 0 ] then
flag=0
break
fi
j=$(( $j+1
)) done
if [ $flag -eq
1 ] then
echo "$i"
fi
i=$(( $i+1
)) done
Output
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2. Write a shell script which will generate first n Fibonacci numbers like: 1,
1, 2, 3, 5, 13,... Knowledge of
Code
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Output
3. Write a shell script to read n numbers as command arguments and sort
them in descending order.
Code
if [ $# -eq 0
] then
echo "Enter valid
Arguments" exit
fi
> temp
for i in $*
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do
echo "$i" >>
temp done
echo "Your sorted
data:" sort -nr temp
echo "End of Script"
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Output
4. Write a shell script to display all executable files, directories and zero
sized files.
Code
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Output
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5.Write a shell script to fetch data from a file and display data into another
file in reverse order.
Code
echo "Enter
filename: " read
file
cat $file | tac >>
reversed.txt echo "$file
content: "
cat $file
echo "nreversed.txt (after reversed)
content:" cat reversed.txt
Output
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Practical: - 5
AIM: -IMPLEMENT FCFS ALGORITHM AND IT'S PREEMPTIVE VERSION
ROUND ROBIN,TAKE NECESSARY ASSUMPTIONS IF NEEDED
FCFS ALGORITHM
package fcfs2;
import java.util.Scanner;
public class Fcfs2
{
int burstTime[];
int arrivalTime[];
String[] processId;
int numberOfProcess;
void getProcessData(Scanner input)
{
System.out.print("Enter the number of Process for Scheduling : ");
int inputNumberOfProcess = input.nextInt();
numberOfProcess = inputNumberOfProcess;
burstTime = new int[numberOfProcess];
arrivalTime = new int[numberOfProcess];
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processId = new String[numberOfProcess];
String st = "P";
for (int i = 0; i < numberOfProcess; i++)
{
processId[i] = st.concat(Integer.toString(i));
System.out.print("Enter the burst time for Process - " + (i) + " : ");
burstTime[i] = input.nextInt();
System.out.print("Enter the arrival time for Process - " + (i) + " : ");
arrivalTime[i] = input.nextInt();
}
}
void sortAccordingArrivalTime(int[] at, int[] bt, String[] pid)
{
boolean swapped;
int temp;
String stemp;
for (int i = 0; i < numberOfProcess; i++)
{
swapped = false;
for (int j = 0; j < numberOfProcess - i - 1; j++)
{
if (at[j] > at[j + 1])
{
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//swapping arrival time
temp = at[j];
at[j] = at[j + 1];
at[j + 1] = temp;
//swapping burst time
temp = bt[j];
bt[j] = bt[j + 1];bt[j + 1] = temp;
//swapping process id
stemp = pid[j];
pid[j] = pid[j + 1];
pid[j + 1] = stemp;
//enhanced bubble sort
swapped = true;
}
}
if (swapped == false)
{
break;
}
}
}
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void Fcfs2()
{
int finishTime[] = new int[numberOfProcess];
int bt[] = burstTime.clone();
int at[] = arrivalTime.clone();
String pid[] = processId.clone();
int waitingTime[] = new int[numberOfProcess];
int turnAroundTime[] = new int[numberOfProcess];
sortAccordingArrivalTime(at, bt, pid);
//calculating waiting & turn-around time for each process
finishTime[0] = at[0] + bt[0];
turnAroundTime[0] = finishTime[0] - at[0];
waitingTime[0] = turnAroundTime[0] - bt[0];
for (int i = 1; i < numberOfProcess; i++)
{
finishTime[i] = bt[i] + finishTime[i - 1];
turnAroundTime[i] = finishTime[i] - at[i];
waitingTime[i] = turnAroundTime[i] - bt[i];
}
float sum = 0;
for (int n : waitingTime)
{
sum += n;
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}
float averageWaitingTime = sum / numberOfProcess;
sum = 0;
for (int n : turnAroundTime)
{
sum += n;
}
float averageTurnAroundTime = sum / numberOfProcess;
//print on console the order of processes scheduled using FirstComeFirstServer Algorithm
System.out.println("FCFS Scheduling Algorithm : ");
System.out.format("%20s%20s%20s%20s%20s%20sn", "ProcessId", "BurstTime",
"ArrivalTime", "FinishTime", "WaitingTime", "TurnAroundTime");
for (int i = 0; i < numberOfProcess; i++)
{
System.out.format("%20s%20d%20d%20d%20d%20dn", pid[i], bt[i], at[i], finishTime[i],
waitingTime[i], turnAroundTime[i]);
}
System.out.format("%80s%20f%20fn", "Average", averageWaitingTime,
averageTurnAroundTime);
}
public static void main(String[] args)
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{
Scanner input = new Scanner(System.in);
Fcfs2 obj = new Fcfs2();
obj.getProcessData(input);
obj.Fcfs2();
}
}
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ROUND ROBIN ALGORITHM
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public class Main
{
// Method to find the waiting time for all
// processes
static void findWaitingTime(int processes[], int n,
int bt[], int wt[], int quantum)
{
// Make a copy of burst times bt[] to store remaining
// burst times.
int rem_bt[] = new int[n];
for (int i = 0 ; i < n ; i++)
rem_bt[i] = bt[i];
int t = 0; // Current time
// Keep traversing processes in round robin manner
// until all of them are not done.
while(true)
{
boolean done = true;
// Traverse all processes one by one repeatedly
for (int i = 0 ; i < n; i++)
{
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// If burst time of a process is greater than 0
// then only need to process further
if (rem_bt[i] > 0)
{
done = false; // There is a pending process
if (rem_bt[i] > quantum)
{
// Increase the value of t i.e. shows
// how much time a process has been processed
t += quantum;
// Decrease the burst_time of current process
// by quantum
rem_bt[i] -= quantum;
}
// If burst time is smaller than or equal to
// quantum. Last cycle for this process
else
{
// Increase the value of t i.e. shows
// how much time a process has been processed
t = t + rem_bt[i];
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// Waiting time is current time minus time
// used by this process
wt[i] = t - bt[i];
// As the process gets fully executed
// make its remaining burst time = 0
rem_bt[i] = 0;
}
}
}
// If all processes are done
if (done == true)
break;
}
}
// Method to calculate turn around time
static void findTurnAroundTime(int processes[], int n,
int bt[], int wt[], int tat[])
{
// calculating turnaround time by adding
// bt[i] + wt[i]
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for (int i = 0; i < n ; i++)
tat[i] = bt[i] + wt[i];
}
// Method to calculate average time
static void findavgTime(int processes[], int n, int bt[],
int quantum)
{
int wt[] = new int[n], tat[] = new int[n];
int total_wt = 0, total_tat = 0;
// Function to find waiting time of all processes
findWaitingTime(processes, n, bt, wt, quantum);
// Function to find turn around time for all processes
findTurnAroundTime(processes, n, bt, wt, tat);
// Display processes along with all details
System.out.println("Processes " + " Burst time " +
" Waiting time " + " Turn around time");
// Calculate total waiting time and total turn
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// around time
for (int i=0; i<n; i++)
{
total_wt = total_wt + wt[i];
total_tat = total_tat + tat[i];
System.out.println(" " + (i+1) + "tt" + bt[i] +"t " +
wt[i] +"tt " + tat[i]);
}
System.out.println("Average waiting time = " +
(float)total_wt / (float)n);
System.out.println("Average turn around time = " +
(float)total_tat / (float)n);
}
// Driver Method
public static void main(String[] args)
{
// process id's
int processes[] = { 1, 2, 3};
int n = processes.length;
// Burst time of all processes
int burst_time[] = {10, 5, 8};
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// Time quantum
int quantum = 2;
findavgTime(processes, n, burst_time, quantum);
}
}
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OUTPUTProcesses Burst time Waiting time Turn around time
1 10 13 23
2 5 10 15
3 8 13 21
Average waiting time = 12.0
Average turn around time = 19.666666
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Practical: - 6
AIM: -implement SJF and SRTN algorithm with necessary assumptions
SJF
package sjf;
import java.util.*;
public class SJF {
public static void main(String args[])
{
try (Scanner sc = new Scanner(System.in)) {
System.out.println ("enter no of process:");
int n = sc.nextInt();
int pid[] = new int[n];
int at[] = new int[n]; // at means arrival time
int bt[] = new int[n]; // bt means burst time
int ct[] = new int[n]; // ct means complete time
int ta[] = new int[n]; // ta means turn around time
int wt[] = new int[n]; //wt means waiting time
int f[] = new int[n]; // f means it is flag it checks process is completed or not
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int st=0, tot=0;
float avgwt=0, avgta=0;
for(int i=0;i<n;i++)
{
System.out.println ("enter process " + (i+1) + " arrival time:");
at[i] = sc.nextInt();
System.out.println ("enter process " + (i+1) + " brust time:");
bt[i] = sc.nextInt();
pid[i] = i+1;
f[i] = 0;
} boolean a = true;
while(true)
{
int c=n, min=999;
if (tot == n) // total no of process = completed process loop will be terminated
break;
for (int i=0; i<n; i++)
{
/*
* If i'th process arrival time <= system time and its flag=0 and burst<min
* That process will be executed first
*/
if ((at[i] <= st) && (f[i] == 0) && (bt[i]<min))
{
min=bt[i];
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c=i;
}
}
/* If c==n means c value can not updated because no process arrival time< system time so
we increase the system time */
if (c==n)
st++;
else
{
ct[c]=st+bt[c];
st+=bt[c];
ta[c]=ct[c]-at[c];
wt[c]=ta[c]-bt[c];
f[c]=1;
tot++;
}
} System.out.println("npid arrival brust complete turn waiting");
for(int i=0;i<n;i++)
{
avgwt+= wt[i];
avgta+= ta[i];
System.out.println(pid[i]+"t"+at[i]+"t"+bt[i]+"t"+ct[i]+"t"+ta[i]+"t"+wt[i]);
} System.out.println ("naverage tat is "+ (float)(avgta/n));
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System.out.println ("average wt is "+ (float)(avgwt/n));
}
}
}
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1
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OUTPUTpid arrival brust complete turn waiting
1 2 2 4 2 0
2 4 4 8 4 0
3 5 6 14 9 3
average tat is 5.0
average wt is 1.0
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SRTF
import java.io.*;
public class SRTF {
public static void main(String args[]) throws IOException
{
BufferedReader br = new BufferedReader(new
InputStreamReader(System.in));
int n;
System.out.println("Please enter the number of Processes:
");
n = Integer.parseInt(br.readLine());
int proc[][] = new int[n + 1][4];//proc[][0] is the AT
array,[][1] - RT,[][2] - WT,[][3] - TT
for(int i = 1; i <= n; i++)
{
System.out.println("Please enter the Arrival Time for
Process " + i + ": ");
proc[i][0] = Integer.parseInt(br.readLine());
System.out.println("Please enter the Burst Time for Process
" + i + ": ");
proc[i][1] = Integer.parseInt(br.readLine());
}
System.out.println();
//Calculation of Total Time and Initialization of Time
Chart array
int total_time = 0;
for(int i = 1; i <= n; i++)
OPERATING SYSTEM IU2141051151
{
total_time += proc[i][1];
}
int time_chart[] = new int[total_time];
for(int i = 0; i < total_time; i++)
{
//Selection of shortest process which has arrived
int sel_proc = 0;
int min = 99999;
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for(int j = 1; j <= n; j++)
{
if(proc[j][0] <= i)//Condition to check if Process has
arrived
{
if(proc[j][1] < min && proc[j][1] != 0)
{
min = proc[j][1];
sel_proc = j;
}
}
}
//Assign selected process to current time in the Chart
time_chart[i] = sel_proc;
//Decrement Remaining Time of selected process by 1 since it
has been assigned the CPU for 1 unit of time
proc[sel_proc][1]--;
//WT and TT Calculation
for(int j = 1; j <= n; j++)
{
if(proc[j][0] <= i)
{
if(proc[j][1] != 0)
{
proc[j][3]++;//If process has arrived and it has not
already completed execution its TT is incremented by 1
if(j != sel_proc)//If the process has not been
currently assigned the CPU and has arrived its WT is incremented
by 1
proc[j][2]++;
}
else if(j == sel_proc)//This is a special case in which
the process has been assigned CPU and has completed its execution
proc[j][3]++;
}
}
//Printing the Time Chart
if(i != 0)
{
if(sel_proc != time_chart[i - 1])
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OPERATING SYSTEM IU2141051151
//If the CPU has been assigned to a different Process we need to
print the current value of time and the name of
//the new Process
{
System.out.print("--" + i + "--P" + sel_proc);
}
}
else//If the current time is 0 i.e the printing has just
started we need to print the name of the First selected Process
System.out.print(i + "--P" + sel_proc);
if(i == total_time - 1)//All the process names have been
printed now we have to print the time at which execution ends
System.out.print("--" + (i + 1));
}
System.out.println();
System.out.println();
//Printing the WT and TT for each Process
System.out.println("Pt WT t TT ");
for(int i = 1; i <= n; i++)
{
System.out.printf("%dt%2dmst%2dms",i,proc[i][2],proc[i][3]);
System.out.println();
}
System.out.println();
//Printing the average WT & TT
float WT = 0,TT = 0;
for(int i = 1; i <= n; i++)
{
WT += proc[i][2];
TT += proc[i][3];
}
WT /= n;
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TT /= n;
System.out.println("The Average WT is: " + WT + "ms");
System.out.println("The Average TT is: " + TT + "ms");
}
}
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PAGE NO 68
OPERATING SYSTEM(CE0418)
OUTPUT—
IU2041050116
BHAVYA SHAH
PAGE NO 69
OPERATING SYSTEM(CE0418)
Practical: - 7
AIM: -IMPLEMENT PREMPTIVE AND NON PREEMPTIVE PRIORITY
SCHEDULING
PRIORITY PREMPTIVE
CODEimport java.util.Scanner;
public class priorityp{
public static void main(String args[]) {
Scanner s = new Scanner(System.in);
int x,n,p[],pp[],bt[],w[],t[],awt,atat,i;
p = new int[10];
pp = new int[10];
bt = new int[10];
w = new int[10];
t = new int[10];
//n is number of process
//p is process
//pp is process priority
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//bt is process burst time
//w is wait time
// t is turnaround time
//awt is average waiting time
//atat is average turnaround time
System.out.print("Enter the number of process : ");
n = s.nextInt();
System.out.print("nt Enter burst time : time priorities n");
for(i=0;i<n;i++)
{
System.out.print("nProcess["+(i+1)+"]:");
bt[i] = s.nextInt();
pp[i] = s.nextInt();
p[i]=i+1;
}
//sorting on the basis of priority
for(i=0;i<n-1;i++)
{
for(int j=i+1;j<n;j++)
{
if(pp[i]>pp[j])
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OPERATING SYSTEM(CE0418)
{
x=pp[i];
pp[i]=pp[j];
pp[j]=x;
x=bt[i];
bt[i]=bt[j];
bt[j]=x;
x=p[i];
p[i]=p[j];
p[j]=x;
}
}
}
w[0]=0;
awt=0;
t[0]=bt[0];
atat=t[0];
for(i=1;i<n;i++)
{
w[i]=t[i-1];
awt+=w[i];
t[i]=w[i]+bt[i];
atat+=t[i];
}
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//Displaying the process
System.out.print("nnProcess t Burst Time t Wait Time t Turn Around Time Priority n");
for(i=0;i<n;i++)
System.out.print("n "+p[i]+"tt "+bt[i]+"tt "+w[i]+"tt "+t[i]+"tt "+pp[i]+"n");
awt/=n;
atat/=n;
System.out.print("n Average Wait Time : "+awt);
System.out.print("n Average Turn Around Time : "+atat);
}
}
OUTPUTPlease enter the number of Processes:
3
Please enter the Arrival Time for Process 1:
4
Please enter the Burst Time for Process 1:
5
Please enter the Arrival Time for Process 2:
6
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OPERATING SYSTEM(CE0418)
Please enter the Burst Time for Process 2:
7
Please enter the Arrival Time for Process 3:
8
Please enter the Burst Time for Process 3:
9
0--P0--4--P1--9--P2--16--P3--21
P WT TT
1 0ms 5ms
2 3ms 10ms
3 8ms 13ms
The Average WT is: 3.6666667ms
The Average TT is: 9.333333ms
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OPERATING SYSTEM(CE0418)
PRIORITY NON – PREMPTIVE
import java.util.*;
/// Data Structure
class Process {
int at, bt, pri, pno;
Process(int pno, int at, int bt, int pri)
{
I =
this.pno = pno;
this.pri = pri;
this.at = at;
this.bt = bt;
}
}
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OPERATING SYSTEM(CE0418)
/// Gantt chart structure
class GChart {
// process number, start time, complete time,
// turn around time, waiting time
int pno, stime, ctime, wtime, ttime;
}
// user define comparative method (first arrival first serve,
// if arrival time same then heigh priority first)
class MyComparator implements Comparator {
public int compare(Object o1, Object o2)
{
Process p1 = (Process)o1;
Process p2 = (Process)o2;
if (p1.at < p2.at)
return (-1);
else if (p1.at == p2.at && p1.pri > p2.pri)
return (-1);
else
return (1);
}
}
// class to find Gantt chart
class FindGantChart {
void findGc(LinkedList queue)
{
// initial time = 0
int time = 0;
// priority Queue sort data according
// to arrival time or priority (ready queue)
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TreeSet prique = new TreeSet(new MyComparator());
// link list for store processes data
LinkedList result = new LinkedList();
// process in ready queue from new state queue
while (queue.size() > 0)
prique.add((Process)queue.removeFirst());
Iterator it = prique.iterator();
// time set to according to first process
time = ((Process)prique.first()).at;
// scheduling process
while (it.hasNext()) {
// dispatcher dispatch the
// process ready to running state
Process obj = (Process)it.next();
GChart gc1 = new GChart();
gc1.pno = obj.pno;
gc1.stime = time;
time += obj.bt;
gc1.ctime = time;
gc1.ttime = gc1.ctime - obj.at;
gc1.wtime = gc1.ttime - obj.bt;
/// store the exxtreted process
result.add(gc1);
}
// create object of output class and call method
new ResultOutput(result);
}
}
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OPERATING SYSTEM(CE0418)
OUTPUTPlease enter the number of Processes:
4
Please enter the Arrival Time for Process 1:
3
Please enter the Burst Time for Process 1:
4
Please enter the Arrival Time for Process 2:
5
Please enter the Burst Time for Process 2:
6
Please enter the Arrival Time for Process 3:
7
Please enter the Burst Time for Process 3:
8
Please enter the Arrival Time for Process 4:
9
Please enter the Burst Time for Process 4:
10
0--P0--3--P1--7--P2--13--P3--21--P4--28
P WT TT
1 0ms 4ms
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OPERATING SYSTEM(CE0418)
2 2ms 8ms
3 6ms 14ms
4 12ms 19ms
The Average WT is: 5.0ms
The Average TT is: 11.25ms
I
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OPERATING SYSTEM(CE0418)
Practical: - 8
AIM: -Implement and Present the output of following Disk scheduling
Algorithms.
a. FIFO
b. SCAN
c. LOOK
a. FIFO
class GFG
{
static int size = 8;
static void FCFS(int arr[], int head)
{
int seek_count = 0;
int distance, cur_track;
for (int i = 0; i < size; i++)
{
cur_track = arr[i];
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// calculate absolute distance
distance = Math.abs(cur_track - head);
// increase the total count
seek_count += distance;
// accessed track is now new head
head = cur_track;
}
System.out.println("Total number of " +
"seek operations = " +
seek_count);
// Seek sequence would be the same
// as request array sequence
System.out.println("Seek Sequence is");
for (int i = 0; i < size; i++)
{
System.out.println(arr[i]);
}
}
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OPERATING SYSTEM(CE0418)
// Driver code
public static void main(String[] args)
{
// request array
int arr[] = { 176, 79, 34, 60,
92, 11, 41, 114 };
int head = 50;
FCFS(arr, head);
}
}
Output
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OPERATING SYSTEM(CE0418)
b. SCAN
// Java program to demonstrate
// SCAN Disk Scheduling algorithm
import java.util.*;
class GFG
{
static int size = 8;
static int disk_size = 200;
static void SCAN(int arr[], int head, String direction)
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{
int seek_count = 0;
int distance, cur_track;
Vector<Integer> left = new Vector<Integer>(),
right = new Vector<Integer>();
Vector<Integer> seek_sequence = new Vector<Integer>();
// appending end values
// which has to be visited
// before reversing the direction
if (direction == "left")
left.add(0);
else if (direction == "right")
right.add(disk_size - 1);
for (int i = 0; i < size; i++)
{
if (arr[i] < head)
left.add(arr[i]);
if (arr[i] > head)
right.add(arr[i]);
}
// sorting left and right vectors
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Collections.sort(left);
Collections.sort(right);
// run the while loop two times.
// one by one scanning right
// and left of the head
int run = 2;
while (run-- >0)
{
if (direction == "left")
{
for (int i = left.size() - 1; i >= 0; i--)
{
cur_track = left.get(i);
// appending current track to seek sequence
seek_sequence.add(cur_track);
// calculate absolute distance
distance = Math.abs(cur_track - head);
// increase the total count
seek_count += distance;
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// accessed track is now the new head
head = cur_track;
}
direction = "right";
}
else if (direction == "right")
{
for (int i = 0; i < right.size(); i++)
{
cur_track = right.get(i);
// appending current track to seek sequence
seek_sequence.add(cur_track);
// calculate absolute distance
distance = Math.abs(cur_track - head);
// increase the total count
seek_count += distance;
// accessed track is now new head
head = cur_track;
}
direction = "left";
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}
}
System.out.print("Total number of seek operations = "
+ seek_count + "n");
System.out.print("Seek Sequence is" + "n");
for (int i = 0; i < seek_sequence.size(); i++)
{
System.out.print(seek_sequence.get(i) + "n");
}
}
// Driver code
public static void main(String[] args)
{
// request array
int arr[] = { 176, 79, 34, 60,
92, 11, 41, 114 };
int head = 50;
String direction = "left";
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SCAN(arr, head, direction);
}
}
OUTPUT
c. LOOK
// Java program to demonstrate
// LOOK Disk Scheduling algorithm
import java.util.*;
class GFG{
static int size = 8;
static int disk_size = 200;
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public static void LOOK(int arr[], int head,
String direction)
{
int seek_count = 0;
int distance, cur_track;
Vector<Integer> left = new Vector<Integer>();
Vector<Integer> right = new Vector<Integer>();
Vector<Integer> seek_sequence = new Vector<Integer>();
// Appending values which are
// currently at left and right
// direction from the head.
for(int i = 0; i < size; i++)
{
if (arr[i] < head)
left.add(arr[i]);
if (arr[i] > head)
right.add(arr[i]);
}
// Sorting left and right vectors
// for servicing tracks in the
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OPERATING SYSTEM(CE0418)
// correct sequence.
Collections.sort(left);
Collections.sort(right);
// Run the while loop two times.
// one by one scanning right
// and left side of the head
int run = 2;
while (run-- > 0)
{
if (direction == "left")
{
for(int i = left.size() - 1;
i >= 0; i--)
{
cur_track = left.get(i);
// Appending current track to
// seek sequence
seek_sequence.add(cur_track);
// Calculate absolute distance
distance = Math.abs(cur_track - head);
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// Increase the total count
seek_count += distance;
// Accessed track is now the new head
head = cur_track;
}
// Reversing the direction
direction = "right";
}
else if (direction == "right")
{
for(int i = 0; i < right.size(); i++)
{
cur_track = right.get(i);
// Appending current track to
// seek sequence
seek_sequence.add(cur_track);
// Calculate absolute distance
distance = Math.abs(cur_track - head);
// Increase the total count
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OPERATING SYSTEM(CE0418)
seek_count += distance;
// Accessed track is now new head
head = cur_track;
}
// Reversing the direction
direction = "left";
}
}
System.out.println("Total number of seek " +
"operations = " + seek_count);
System.out.println("Seek Sequence is");
for(int i = 0; i < seek_sequence.size(); i++)
{
System.out.println(seek_sequence.get(i));
}
}
// Driver code
public static void main(String[] args) throws Exception
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{
// Request array
int arr[] = { 176, 79, 34, 60,
92, 11, 41, 114 };
int head = 50;
String direction = "right";
System.out.println("Initial position of head: " +
head);
LOOK(arr, head, direction);
}
}
Output
IU2041050116
BHAVYA SHAH
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OPERATING SYSTEM(CE0418)
IU2041050116
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PAGE NO 97
OPERATING SYSTEM(CE0418)
Practical: - 9
AIM: -Implement and Present the output of following Page Replacement
Algorithm.
A. FIFO
B. OPTIMAL
A. FIFO
// Java implementation of FIFO page replacement
// in Operating Systems.
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Queue;
class Test
{
// Method to find page faults using FIFO
static int pageFaults(int pages[], int n, int capacity)
{
// To represent set of current pages. We use
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// an unordered_set so that we quickly check
// if a page is present in set or not
HashSet<Integer> s = new HashSet<>(capacity);
// To store the pages in FIFO manner
Queue<Integer> indexes = new LinkedList<>() ;
// Start from initial page
int page_faults = 0;
for (int i=0; i<n; i++)
{
// Check if the set can hold more pages
if (s.size() < capacity)
{
// Insert it into set if not present
// already which represents page fault
if (!s.contains(pages[i]))
{
s.add(pages[i]);
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// increment page fault
page_faults++;
// Push the current page into the queue
indexes.add(pages[i]);
}
}
// If the set is full then need to perform FIFO
// i.e. remove the first page of the queue from
// set and queue both and insert the current page
else
{
// Check if current page is not already
// present in the set
if (!s.contains(pages[i]))
{
//Pop the first page from the queue
int val = indexes.peek();
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indexes.poll();
// Remove the indexes page
s.remove(val);
// insert the current page
s.add(pages[i]);
// push the current page into
// the queue
indexes.add(pages[i]);
// Increment page faults
page_faults++;
}
}
}
return page_faults;
}
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// Driver method
public static void main(String args[])
{
int pages[] = {7, 0, 1, 2, 0, 3, 0, 4,
2, 3, 0, 3, 2};
int capacity = 4;
System.out.println(pageFaults(pages, pages.length, capacity));
}
}
Output
B. OPTIMAL
// CPP program to demonstrate optimal page
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// replacement algorithm.
#include <bits/stdc++.h>
using namespace std;
// Function to check whether a page exists
// in a frame or not
bool search(int key, vector<int>& fr)
{
for (int i = 0; i < fr.size(); i++)
if (fr[i] == key)
return true;
return false;
}
// Function to find the frame that will not be used
// recently in future after given index in pg[0..pn-1]
int predict(int pg[], vector<int>& fr, int pn, int index)
{
// Store the index of pages which are going
// to be used recently in future
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int res = -1, farthest = index;
for (int i = 0; i < fr.size(); i++) {
int j;
for (j = index; j < pn; j++) {
if (fr[i] == pg[j]) {
if (j > farthest) {
farthest = j;
res = i;
}
break;
}
}
// If a page is never referenced in future,
// return it.
if (j == pn)
return i;
}
// If all of the frames were not in future,
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// return any of them, we return 0. Otherwise
// we return res.
return (res == -1) ? 0 : res;
}
void optimalPage(int pg[], int pn, int fn)
{
// Create an array for given number of
// frames and initialize it as empty.
vector<int> fr;
// Traverse through page reference array
// and check for miss and hit.
int hit = 0;
for (int i = 0; i < pn; i++) {
// Page found in a frame : HIT
if (search(pg[i], fr)) {
hit++;
continue;
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}
// Page not found in a frame : MISS
// If there is space available in frames.
if (fr.size() < fn)
fr.push_back(pg[i]);
// Find the page to be replaced.
else {
int j = predict(pg, fr, pn, i + 1);
fr[j] = pg[i];
}
}
cout << "No. of hits = " << hit << endl;
cout << "No. of misses = " << pn - hit << endl;
}
// Driver Function
int main()
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{
int pg[] = { 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2 };
int pn = sizeof(pg) / sizeof(pg[0]);
int fn = 4;
optimalPage(pg, pn, fn);
return 0;
}
OUtPUT
IU2041050116
BHAVYA SHAH
PAGE NO 107
OPERATING SYSTEM(CE0418)
Practical: - 10
AIM: -Implement and Present the output of following Page Replacement
Algorithm.
A. LRU
CODEimport java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
class Test
{
// Method to find page faults using indexes
static int pageFaults(int pages[], int n, int capacity)
{
// To represent set of current pages. We use
// an unordered_set so that we quickly check
// if a page is present in set or not
HashSet<Integer> s = new HashSet<>(capacity);
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// To store least recently used indexes
// of pages.
HashMap<Integer, Integer> indexes = new HashMap<>();
// Start from initial page
int page_faults = 0;
for (int i=0; i<n; i++)
{
// Check if the set can hold more pages
if (s.size() < capacity)
{
// Insert it into set if not present
// already which represents page fault
if (!s.contains(pages[i]))
{
s.add(pages[i]);
// increment page fault
page_faults++;
}
// Store the recently used index of
// each page
indexes.put(pages[i], i);
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}
// If the set is full then need to perform lru
// i.e. remove the least recently used page
// and insert the current page
else
{
// Check if current page is not already
// present in the set
if (!s.contains(pages[i]))
{
// Find the least recently used pages
// that is present in the set
int lru = Integer.MAX_VALUE, val=Integer.MIN_VALUE;
Iterator<Integer> itr = s.iterator();
while (itr.hasNext()) {
int temp = itr.next();
if (indexes.get(temp) < lru)
{
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lru = indexes.get(temp);
val = temp;
}
}
// Remove the indexes page
s.remove(val);
//remove lru from hashmap
indexes.remove(val);
// insert the current page
s.add(pages[i]);
// Increment page faults
page_faults++;
}
// Update the current page index
indexes.put(pages[i], i);
}
}
return page_faults;
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}
// Driver method
public static void main(String args[])
{
int pages[] = {7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2};
int capacity = 4;
System.out.println(pageFaults(pages, pages.length, capacity));
}
}
OUTPUTPlease enter the number of Processes:
4
Please enter the Arrival Time for Process 1:
2
Please enter the Burst Time for Process 1:
3
Please enter the Arrival Time for Process 2:
4
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OPERATING SYSTEM(CE0418)
Please enter the Burst Time for Process 2:
5
Please enter the Arrival Time for Process 3:
6
Please enter the Burst Time for Process 3:
7
Please enter the Arrival Time for Process 4:
8
Please enter the Burst Time for Process 4:
9
0--P0--2--P1--5--P2--10--P3--17--P4--24
P WT TT
1 0ms 3ms
2 1ms 6ms
3 4ms 11ms
4 9ms 16ms
The Average WT is: 3.5ms
The Average TT is: 9.0ms
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