Operating Systems Lab Cycle - I Programs

 

List of programs

Cycle-1:

Execute various UNIX system calls

1. Process Management

2. File Management

3. Input/Output System Calls

 

Cycle-2:

Simulate the following CPU scheduling algorithms.

a) FCFS    b) SJF    c) Round Robin    d) Priority.

 

Cycle-3:

Simulate the file allocation strategies:

a)    Sequential  b) indexed  c)  Linked

 

Cycle-4:

Simulate MVT and MFT

simulate contiguous memory allocation techniques

a)    Worst-fit b) Best fit c) First fit

 

Cycle-5:

Simulate all File Organization techniques

A) Single level directory b) Two level c)Hierarchical d)DAG

 

          Cycle-6:

        Simulate Bankers Algorithm for Deadlock Avoidance

           Simulate Bankers algorithm for Deadlock Prevention

 

       Cycle-7:

       Simulate disk scheduling algorithms.

         a) FCFS b) SCAN c) C-SCAN

 

          Cycle-8:

        Programs on process creation and synchronization, inter process communication

            Including shared memory , pipes and

 

Cycle-1: Execute various UNIX system calls

--------------------------------------------------------------------------------

1)Process Management system calls

 

a)  Aim: To write C programs to simulate UNIX command fork()

Program:

 

#include<stdio.h> #include<sys/types.h> main()

 {    int pid;

    pid=fork();

   if(pid==0)

{

printf("\n I am the child");

printf("\n I am the parent :%d",getppid());

printf("\n I am the child :%d",getpid());

   }   

Else

{

 printf("\n I am the parent ");

 printf("\n I am the parents parent :%d",getppid()); printf("\n I am the parent :%d\n",getpid());

   }

}

 

 

Output:

I am the child

I am the  parent:  3944

I am the child:  3945

I am the parent

I am the parents parent:  3211

I am the parent:  3944

 

 b)Aim: To write C programs to simulate UNIX command execv()

Program: 

#include<stdio.h>

 #include<unistd.h>

 main()

{

 char *temp[3];

temp[0]="ls";

temp[1]="-l";

temp[2]=(char *)0;

execv("/bin/ls",temp);

printf("this will not print\n");

}

 

Output:

total 76

-rwxr-xr-x    1 be322    group     4716 Mar 7 10:13  a.out

-rw-r--r--    1 be322    group      688 Feb 20  13:52  comm.c

-rw-r--r--    1 be322    group      925 Feb 20  13:54  echomsg.c

-rw-r--r--    1 be322    group      722 Feb 20  13:55  echopipe.c

-rw-r--r--    1 be322    group      178 Feb 20  13:57  exel.c

-rw-r--r--    1 be322    group      167 Mar 7   10:13  exev.c

-rw-r--r--    1 be322    group     1109 Feb 20 13:57  fflag.c

-rw-r--r--    1 be322    group      341 Dec 26  14:47  frk.c

-rw-r--r--    1 be322    group      140 Feb 20  13:57  linearg.c

-rw-r--r--    1 be322    group      528 Feb 20  13:57  lock.c

-rw-r--r--    1 be322    group      254 Feb 20  13:57  msg.c

-rw-r--r--    1 be322    group     1036 Feb 20 13:57  msgpass.c

-rw-r--r--    1 be322    group      203 Feb 20  13:58  sem.c

-rw-r--r--    1 be322    group     1167 Feb 20 13:58  sharememory.c

-rw-r--r--    1 be322    group      312 Feb 20  13:58  slp.c

-rw-r--r--    1 be322    group     1182 Feb 20 13:58  threadf.c

-rw-r--r--    1 be322    group      287 Feb 20  13:59  wt.c


 c)Aim: To write C programs to simulate UNIX command execlp()

Program:

#include<stdio.h> #include<sys/types.h>

main()

 {  

   int pid;     

    pid=fork();

     if(pid==0)

    {

printf("\n fork program started");

execlp("/bin/ls","ls",NULL);

     }     

else

    {

printf("\nend");

    }

}

 

OUTPUT:

end$

 fork program started a.out

comm.c echomsg.c echopipe.c exel.c exev.c fflag.c frk.c linearg.c lock.c msg.c msgpass.c sem.c

sharememory.c

slp.c threadf.c

wt.c

 

 d)Aim: To write C programs to simulate UNIX command wait()

Program:

#include<unistd.h>

 #include<stdio.h>

 main()

{

int i=0,pid;

 pid=fork();

 if(pid==0)

{

 printf("child  process started\n");

for(i=0;i<10;i++)    

 printf("\n%d",i);

 printf("\n child process ends");

}

 else

{

printf("\n parent process starts");

 wait(0);

printf("\n parent process ends");

}

}

 

Output:

parent process starts

 child  process started

 

0

1

2

3

4

5

6

7

8 9  child process ends

 parent process ends

 

e)Aim: To write C programs to simulate UNIX command sleep()

                      Program :

#include<unistd.h>

#include<stdio.h>

main()

{

int i=0,pid;

printf("\n ready for fork\n");

pid=fork(); if(pid==0)

{

printf("\n child process started \n");

sleep(4);

for(i=0;i<10;i++)    

 printf("\n%d",i);

printf("\n child process ends");

}

else

{

printf("\n I am the parent");

printf("\n parent process ends");

}

}

 

Output:

ready for fork

 I am the parent 

parent process ends

child process started

 

0

1

2

3

4

5

6

7

8 9

 child process ends

2)File Management System calls or I/O System calls

a)Aim: To write C programs to simulate UNIX command pipe()

  Program :

#include<stdio.h>

#include<unistd.h>

#include<sys/ipc.h>

#include<sys/types.h>

 #define msgsize 16 main()

{

char *msg="hello world";

 char inbuff[msgsize];

int p[2],pid,j;

pipe(p);

 pid=fork();

if(pid>0)

{

close(p[0]);

 write(p[1],msg,msgsize);

}

if(pid==0)

{

close(p[1]);

read(p[0],inbuff,msgsize);

printf("%s \n",inbuff);

}}

Output:

 hello world

b)Aim: To write C programs to create semaphore id

 Program :

 

#include<unistd.h>

 #include<sys/ipc.h>

 main()

{

 int semid,key,nsem,flag;

 key=(key_t)0X200f;

flag=IPC_CREAT|0666;

nsem=1;

semid=semget(key,nsem,flag);

printf("Created a semaphore with  id: %d \n",semid);

}

Output:

Created a semaphore with id: 589832


 c)Aim: To write C programs to create shared memory id

 Program :

 

#include<sys/types.h>

#include<sys/ipc.h> #include<sys/shm.h> main()

{

int shmid,flag;

key_t key=0X1000; shmid=shmget(key,10,IPC_CREAT|0666);

if(shmid<0)

{

perror("shmid failed");

exit(1);

}

printf("Success shmid is %d /n",shmid);

}

 

Output:

Success shmid is: 682340

 

d)Aim: To write a C program for simulating  File management process(Read,Write)

Program:

#include <unistd.h>

#include <sys/types.h>

#include <fcntl.h>

main()

{

int fd1,fd2,n;

char *ch;

fd1=open("file1", O_CREAT|O_RDWR,0666);

if(fd1==-1)

{

printf("source filw cannot be processed \n");

exit(0);

}

fd2=open("file2",O_CREAT|O_RDWR,0666);

if(fd2==-1)

{

printf("destination file cannot be processed \n");

exit(0);

}

while(1)

{

n=read(fd1,ch,1);

if(n==0)

41

break;

write(fd2,ch,1);

}

close(fd1);

close(fd2);

}

Output:

vi file1

good morning

cc filerw.c

./a.out

vi file2

good morning

 

 

 

3)Input/Output System calls

 

Write a C program to simulate  IO System calls

AIM: To write a C program for simulating  IO System calls

Program:

#include<stdio.h>

#include<unistd.h>

#include<string.h>

#include<fcntl.h>

main( )

{

int fd[2];

char buf1[25]= "just a test\n";

char buf2[50];

fd[0]=open("file1",O_RDWR);

fd[1]=open("file2",O_RDWR);

write(fd[0], buf1, strlen(buf1));

printf("\n Enter the text now….");

scanf("\n %s",buf1);

printf("\n Cat file1 is \n hai");

write(fd[0], buf1, strlen(buf1));

lseek(fd[0], SEEK_SET, 0);

read(fd[0], buf2, sizeof(buf1));

write(fd[1], buf2, sizeof(buf2));

close(fd[0]);

close(fd[1]);

printf("\n");

return 0;

}

 

Output:

           Enter the text now….abcdef

 

           Cat file1 is

           hai

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