#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <pthread.h>

// gcc -o p1 p1.c -lpthread

void *thread_main(int *tid)
{
  printf("My (real) thread id = %d, process id = %d\n", gettid(), getpid());
  printf("My thread id from my parent = %d\n", *tid);

  return NULL;
}

int main(void)
{
  pthread_t thread_handle1, thread_handle2;
  int thread_id1 = 1, thread_id2 = 2;

  printf("parent thread id = %d, process id = %d\n", gettid(), getpid());
  // Create (like fork then runs thread_main) the thread:
  pthread_create(&thread_handle1, NULL, (void *)thread_main, &thread_id1);
  pthread_create(&thread_handle2, NULL, (void *)thread_main, &thread_id2);

  // Wait for the thread we created to finish:
  pthread_join(thread_handle1, NULL);
  pthread_join(thread_handle2, NULL);

  return 0;
}