Getpid()UNIX System Call

#include <stdio.h>

#include <sys/types.h>

int main ()

{

  pid_t child_pid;

  printf("the main program process ID is %d\n", (int) getpid ());

  child_pid = fork ();

  if (child_pid != 0) {

    printf("this is the parent process, with id %d\n", (int) getpid ());

    printf("the child’s process ID is %d\n", (int) child_pid);

  }

  else

    printf ("this is the child process, with id %d\n", (int) getpid ());

  return 0;

}

output

 [telnet23@linux ~]$ ./a.out

the main program process ID is 3045

this is the child process,with id 3046

this is the parent process,with id 3045

 the child`s process ID 3046