Programming

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

int child, parent;
char command [100];
int GetPID (int);

int main()
{
child = getpid();
printf ("pid is %d\n", child);

parent = getppid();
printf ("parent pid is %d\n", parent);
GetPID (parent);

sprintf (command, "ps -p %d -o pid,cmd", child);
system (command);
sprintf (command, "ps -p %d -o pid,cmd", parent);
system (command);

return (0);
}

int GetPID (child)
{
child  = getpid();
printf ("grandparent pid \n");
sprintf (command, "ps -p %d -o ", child);
system (command);
return child;
}

$ cat pppid.c

#include <stdio.h>
#include <unistd.h>


int main(void)
{
        FILE *fp;
        int pid;
        char buf[128];
 int n=1;

        printf("pid=%d\n", (int)getpid());
        printf("ppid=%d\n", (int)getppid());

 pid=getppid();

 while(pid>1)
 {
         sprintf(buf, "/proc/%d/stat", (int)pid);
         fp=fopen(buf, "r");
  if(fp == NULL) break;

  // Ignore one number, then two strings, then read a number
         fscanf(fp, "%*d %*s %*s %d", &pid);
         fclose(fp);
         printf("gp%d id=%d\n", n++, (int)pid);
 }
}

$ gcc pppid.c
$ ./a.out
pid=11034
ppid=5249
gp1 id=5248
gp2 id=5245
gp3 id=4000
gp4 id=1
$