Write a program (using fork() and/or exec() commands) where parent and child execute: a) same program, same code. b) same program, different code. - c) before terminating, the parent waits for the child to finish its task.

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#include<iostream>
#include<stdio.h>
#include<sys/types.h>
#include<unistd.h>
using namespace std;

int main()
{
    pid_t pid;
    pid=fork();
    if(pid<0)
    {
        cout<<"this is a process";
    }
    else
    {
        cout<<"process continues";
    }
    return 0;
}

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(b) same program, different code

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#include<iostream>
#include<stdio.h>
#include<unistd.h>
#include<sys/types.h>
using namespace std;

int main()
{
pid_t pid;
pid=fork();
if(pid<0)
{
cout<<"new process not entered";
}
else if(pid==0){
cout<<"Child process";
}
else
cout<<"parent process";
return 0;
}

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(c) different programs

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#include<iostream>
#include<stdio.h>
#include<unistd.h>
#include<sys/types.h>
using namespace std;

int main(){
pid_t pid;
pid=fork();
if(pid<0){
cout<<"No process entered";
}
else if(pid==0){
execlp("/bin/ls","ls",NULL);
cout<<"child process";
}
else {
cout<<"parent process";
}
return 0;
}

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(d) before terminating, the parent waits for the child to finish its task

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#include<stdio.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/wait.h>
using namespace std;

int main(){
pid_t pid;
pid=fork();
if(pid<0){
cout<<"No process entered";
}
else if(pid==0){
execlp("/bin/ls","ls",NULL);
cout<<"child process";
}
else {
wait(NULL);
cout<<"parent process";
}
return 0;
}

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