Linux-Process-API-fork-wait-exec-

Ex02-Linux Process API-fork(), wait(), exec()

Ex02-OS-Linux-Process API - fork(), wait(), exec()

Operating systems Lab exercise

AIM:

To write C Program that uses Linux Process API - fork(), wait(), exec()

DESIGN STEPS:

Step 1:

Navigate to any Linux environment installed on the system or installed inside a virtual environment like virtual box/vmware or online linux JSLinux (https://bellard.org/jslinux/vm.html?url=alpine-x86.cfg&mem=192) or docker.

Step 2:

Write the C Program using Linux Process API - fork(), wait(), exec()

Step 3:

Test the C Program for the desired output.

PROGRAM:

C Program to print process ID and parent Process ID using Linux API system calls

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
int main(void)
{	//variable to store calling function's process id
	pid_t process_id;
	//variable to store parent function's process id
	pid_t p_process_id;
	//getpid() - will return process id of calling function
	process_id = getpid();
	//getppid() - will return process id of parent function
	p_process_id = getppid();
	//printing the process ids

//printing the process ids
	printf("The process id: %d\n",process_id);
	printf("The process id of parent function: %d\n",p_process_id);
	return 0; }

##OUTPUT

#$ps

C Program to create new process using Linux API system calls fork() and exit()

#include <stdio.h>
#include<stdlib.h>
int main()
{ 
int pid; 
pid=fork(); 
if(pid == 0) 
{ 
printf("Iam child my pid is %d\n",getpid()); 
printf("My parent pid is:%d\n",getppid()); 
exit(0); 
} 
else{ 
printf("I am parent, my pid is %d\n",getpid()); 
sleep(100); 
exit(0);
} 
}

##OUTPUT

C Program to execute Linux system commands using Linux API system calls exec() family

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <sys/types.h>
int main()
{
        int status;
        printf("Running ps with execlp\n");
        execl("ps", "ps", "ax", NULL);
        wait(&status);
        if (WIFEXITED(status))
                printf("child exited with status of %d\n", WEXITSTATUS(status));
        else
                printf("child did not exit successfully\n");
                printf("Done.\n");
                printf("Running ps with execlp. Now with path specified\n");
                execlp("/bin/ps", "ps", "ax", NULL);
        wait(&status);
        if (WIFEXITED(status))
                printf("child exited with status of %d\n", WEXITSTATUS(status));
        else
                printf("child did not exit successfully\n");
        printf("Done.\n");
        exit(0);
}

##OUTPUT

RESULT:

The programs are executed successfully.

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