exp1

gistfile1.txt

#include<stdio.h>
#include <sys/types.h> 
#include <unistd.h> 
#include <sys/types.h>
#include <sys/wait.h>
#include <stdlib.h>

int main() {
    
    int nprocesses = 3;
    pid_t pids[32];

    
    if (getpid() != pids[0]){
        printf("initial process is %d\n", getpid());
        pids[0] = getpid();
    }

    
    for (int i = 1; i <= nprocesses; /**/) {
        int pid = fork();
        if(pid < 0){ /*unsuccessful process*/
            exit(EXIT_FAILURE);
        }
        else if (pid > 0){ /*parent process*/
            // store process id per creation order
            pids[i] = pid;
            ++i;
            // wait for all childs to finish before the parent finishes itself
            waitpid(-1, NULL, WUNTRACED);

        }
        else{ /*child*/
            // just finish the child proc.
            exit(EXIT_SUCCESS);
            
        }
    }
    
    for (int i = 1; i <= nprocesses; ++i) {
        // wait for each process to end before starting another
        waitpid(pids[i], 0, 0);
        printf("finished process %d - parent process is %d\n", pids[i], pids[i-1]);
      
    }
    
}