03 Processes 2

`getpid()`¶

Used to display the id of the process that invokes it

`getppid()`¶

Get parent’s process ID

`wait(NULL)`¶

parent process waits for completion of any one of its children

Parent initially moves to wait state, then comes to ready queue

Dependencies¶

#include <sys/types.h>
#include <sys/wait.h>

return value¶

pid of the terminated child

exit status of child¶

integer value

+ve: sucessful termination
-ve : unsuccessful termination

pid_t wait(int *status);

int status;
pid = wait(&status);

Code 1¶

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

#include <sys/types.h>
#include <sys/wait.h>
void main()
{
  int rv, a;
  rv = fork();

  if(rv == 0)
  {
        printf("Hello\n");
    printf("Child PID is %d\n", getpid());
    printf("My parent's PID is %d\n", getppid());
  }
  else if(rv > 0)
  {
    a = wait(NULL);
    printf("Parent PID is %d\n", getpid());
    printf("Parent: The child that terminated is %d\n", a);
  }
  else
  {
    printf("Unsuccessful");
  }
}

Hello
Child PID is 1676
My parent's PID is 1672
Parent PID is 1672
Parent: The child that terminated is 1676

2026-10-15