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

int main()
{
  int x = 100;
  pid_t pid;  /* process id */

  /* fork a child process */
  pid = fork();  /*** fork() returns twice... ***/

  if ( pid < 0 ) {
    fprintf( stderr, "ERROR: fork() failed.\n" );
    exit( 1 );
  }

  if ( pid == 0 )  /* child */
  {
    printf( "CHILD: I'm new.\n" );

    x++;
    printf( "CHILD: x is %d\n", x );
    exit( 0 );

  }
  else /* parent (pid > 0) */
  {
    printf( "PARENT: created process id %d\n", pid );

    /* wait until child terminates */
    wait( NULL );
    printf( "PARENT: child process terminated" );

    printf( "PARENT: x is %d\n", x );
  }

  return 0;
}