apache user checking

[albert85]

i want to ask that can apache server check the current user access. before i update the server, i need to make sure no user access the server. how i check this???
if hav user access server on that time i need to block the server to other and wait the user finish their transaction then i will close down my server, how to perform this????

Anyone can answer my this question? anyone hav the better idea to update server plz reply me ...thank you

regards,
albert