wrote...
We all have seen the movies were one pistol shot or what not causes
the side of an airliner explode sucking the people, seats, etc. into
the void. What would happen in the reality? Let's assume the plane is
at the cruising altitude.

Let's further assume the bullet goes through the aluminum skin. It would result
in a hole about 1/2" in diameter and probably a loud whistling of escaping air.
The outflow valves that control pressurization would close slightly to
compensate for the air loss. You're left with the noise, exacerbated by
screaming/panicking passengers. Put a pillow over the hole to stop the
whistling; that may stop the screaming.

Worse case would be a window. The bullet might cause the entire window to fail.
Since the window is similar in size to the outflow valves, the cabin pressure
would probably begin to decrease slowly as the air rushes out. Unrestrained
objects may be sucked out. A dinner tray or piece of a serving cart could be
used to block the hole, if it could be maneuvered into place.