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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
Last Updated: 2023-01-25 ; Contributors: AhmedThahir

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