Apache: The Definitive Guide, 3rd Edition

Several Copies of Apache

To get a display of all the processes running, run:

% ps -aux

Among a lot of Unix stuff, you will see one copy of httpd belonging to root and a number that belong to webuser. They are similar copies, waiting to deal with incoming queries.

The root copy is still attached to port 80 — thus its children will be as well — but it is not listening. This is because it is root and has too many powers for this to be safe. It is necessary for this “master” copy to remain running as root because under the (slightly flawed) Unix security doctrine, only root can open ports below 1024. Its job is to monitor the scoreboard where the other copies post their status: busy or waiting. If there are too few waiting (default 5, set by the MinSpareServers directive in httpd.conf ), the root copy starts new ones; if there are too many waiting (default 10, set by the MaxSpareServers directive), it kills some off. If you note the PID (shown by ps -ax, or ps -aux for a fuller listing; also to be found in ... /logs/httpd.pid ) of the root copy and kill it with:

% kill 
               PID

you will find that the other copies disappear as well.

It is better, however, to use the stop script described in Section 2.3 earlier in this chapter, since it leaves less to chance and is easier to do.