title: System call invoked when writing into a heap memory
body: <p>I know for malloc sbrk is the system call invoked ,Similarly What is the system cal invoked when i write to a malloed memory(heap memory)</p>
  
  <pre><code>int main
  
  {
  
    /* 10 byte of heap memory allocated */
    char *ptr = malloc(5);
  
  
    ptr[0] = 10;  // **What is the system call invoked for 
                      writing into this heap memory** ?????
  
  
  }
  </code></pre>