That's ppt base on fork system call in operating system

1. Group E4
20CP205 AVNI ROHIT
21CP308 PARAM PATEL
21CP310 IRBAAZ VOHRA

2. 1. Demonstrate the use of fork system call.
• Fork system call is used to create a new process, called the child
process.
• Child process runs concurrently with the process that makes the
fork() call, i.e. parent process.
• After a new child process is created, both processes will execute the
next instruction followed by the fork() system call.
• The fork() takes no parameters and returns an integer value.
• If the value < 0, then the creation of the child process failed.
• If value = 0, then returned to the newly created child process
• If value > 0, then parent is returned, and value = PID of child
process.

3. What is the output of the
following program?
 A)
 int main()
 {
 fork();
 printf("nHellon");
 return 0;
 }

4. OUTPUT
Parent
Process
Child
Process
Parent
Process

5.  B)
 int main()
 {
 fork();
 fork();
 printf("nHellon");
 return 0;
 }
Parent
Process
Parent
Process
Child
Process
(C1)
Parent
Process
Child
Process
(C2)
Child
Process
(C1)
Child
Process
(C3)

6. OUTPUT

7. 2. Demonstrate printing PID of child
and parent process.
 #include <stdio.h>
 #include <sys/types.h>
 #include <unistd.h>
 int main()
 {
 int id = fork();
 if(id==0)
 {
 printf("nChild Process PID : %dn",getpid()
 printf("nParent PID : %dn",getppid());
 }

8.  else
 {
 printf(“nParent Process PID : %dn",getpid());
 sleep(2);
 }
 return 0;
 }

10. 3. Demonstrate use of wait system call. How parent knows child
terminate normally or abnormally after checking return values of
wait .
A)

11. OUTPUT

12. B)

13. OUTPUT

14. 4.Demonstrate use of execl, execv, execve, execlp,
execvp, execle.
 Execl :
execl() call replaces the image of the current process with
a new process image specified by the path i.e. the current
process code gets replaced by a new process code.

15.  Execv(path,argv) :
causes the current process to abandon the program that it is
running and start running the program in file path. Parameter
argv is the argument vector for the command, with a null
pointer at the end. It is an array of strings.
 Execve :
execve() executes the program pointed to by filename.
filename must be either a binary executable,

16.  execlp :
The execlp function is most commonly used to overlay a
process image that has been created by a call to the fork
function. identifies the location of the new process image
within the hierarchical file system (HFS).

17.  execvp and execle :
These two also serve the same purpose but the syntax of them
are a bit different from all the above members of exec family.
The syntaxes of both of them are shown below :
Syntax: int execvpe(const char *file, char *const argv[],char
*const envp[]);
Syntax:int execle(const char path, const char *arg, .../, (char
*) NULL, char * const envp[] */);

18.  5. Demonstrate Zombie Process and Orphan Process
 Zombie Process: A Process Which Terminate But Whose
Parent Not Yet Called Wait() is Known As Zombie Process
 Once The Parent Calls Wait() the Process Identifier of the
Process and its entry in the Zombie process the table is
released
 A child Process Always First Becomes a Zombie Before
Removed From the Process Table

19.  #include<stdio.h>
 #include<unistd.h>
 int main()
 {
 pid_t t;
 t=fork();
 if(t==0)
 {
 printf("Child having id %dn",getpid());
 }
 else
 {
 printf("Parent having id %dn",getpid());
 sleep(15); // Parent sleeps. Run the ps command
 }
 }

20.  Output :
 $gcc zombie.c
 $./a.out &

21. Orphan Process :
 A Process Whose Parent Process no More Exist i.e. either finished or
Terminated Without Waiting for Its Child Process To Terminate Is
Called an Orphan Process
 The Init Process Is Assigned As The New Parent To Orphan Process
 The Init Process Periodically Invokes wait(), There By Allowing The
Exit Status Of Any Orphaned Process to be collected and Relesing
Orphans Process identifier and Process Entry Table

22. #include<stdio.h >
 #include<unistd.h>
 #include<sys/types.h>
 int main()
 {
 pid_t p;
 p=fork();
 if(p==0)
 {
 sleep(5); //child goes to sleep and in the mean time parent
 terminates
 printf("I am child having PID %dn",getpid());
 printf("My parent PID is %dn",getppid());
 }
 else
 {

23.  Output :

24. 6. Develop user defined function which allow to run
binary file and give control back to your parent process
similar to library function system
 Ex1.c
 #include<stdio.h>
 #include<unistd.h>
 #include<stdlib.h>
 Int main(int argc,char *argv[])
 {
 Printf(“PID of EX1.c= %dn”, getpid());
 Char *args[] = {“Hello”,”Vahora”,”Irbaz”,NULL};
 Execv(“./ex2”,args);
 Printf(“Back To ex1.c”);
 Return 0;
}

25.  Ex2.c
 #include<stdio.h>
 #include<unistd.h>
 #include<stdlib.h>
 Int main(int argc,char *argv[])
 {
 Printf(“We Are In Ex2.cn”)
 Printf(“PID of EX2.c= %dn”, getpid());
 Return 0;
}

26. OUTPUT