The following sums up important points to note when a predecessor process execs a successor:

• The successor process overwrites (or overlays) the predecessor's virtual address space.
  • In effect, the predecessor's text, data, library, and stack segments are now replaced by that of the successor's.
  • The OS will take care of the size adjustments.
• No new process has been created—the successor now runs in the context of the old predecessor.
  
  • Several predecessor attributes (including but not limited to the PID and open files) thus get auto-inherited by the successor.
    (The astute reader could then question why, in our previous example, the PID of ps is not 3,396 ? Patience, please, we shall have the precise answer on the GitHub repository).

• On a successful exec, there is no possibility of returning to the predecessor; it's gone. Colloquially, performing an exec is like committing suicide for the predecessor: After successful execution, the successor is all that's left; returning to the predecessor is out of the question: