Download Web Server Management: Running Apache 2 on Red Hat Linux

Chapter 3. Getting started
Listen 80
User
apache
Group
apache
ServerRoot /etc/httpd
Options None
Figure 3-8. httpd.conf: Minimal version
Syntax summary: Getting launched
Listen
This specifies the network interface the server should listen on. If only a port
is specified then it will listen on every active network address. (Typically the
system’s own network address and the loopback address.)
User
This specifies the system user ID that the server process should run as. This user
was created by the Red Hat Linux Apache package.
Group
This specifies the system group ID that the server process should run as. This
group was created by the Red Hat Linux Apache package.
ServerRoot
All unqualified filenames in the configuration file will be resolved with respect
to this directory except for the actual web pages which will be handled by a
different command.
Options
This command sets various parameters in the configuration. We will meet these
through the course as we turn them on.
And if we start the web server now, with this five line configuration file, it launches
just fine and stays running.
# /etc/init.d/httpd start
Starting httpd:
[ OK ]
# tail -1 /var/log/httpd/error_log
[Mon Mar 17 18:02:56 2003] [notice] Apache/2.0.40 (Red Hat Linux) configured -- resuming norma
# ps -ef | grep httpd
root
9344
1 0 18:02 ?
00:00:00 /usr/sbin/httpd
apache
9345 9344 0 18:02 ?
00:00:00 /usr/sbin/httpd
apache
9346 9344 0 18:02 ?
00:00:00 /usr/sbin/httpd
apache
9349 9344 0 18:02 ?
00:00:00 /usr/sbin/httpd
apache
9350 9344 0 18:02 ?
00:00:00 /usr/sbin/httpd
apache
9351 9344 0 18:02 ?
00:00:00 /usr/sbin/httpd
root
9357 8826 0 18:05 pts/3
00:00:00 grep httpd
Figure 3-9. Successful launch
But, as the figure shows, it’s not a single daemon that gets launched. There are six of
them. The first column of the ps output gives the owner of the process and the second
gives the process ID or PID. One of the server processes is owned by user root and
the others by user apache. That root-owned process is the parent process of all the
other processes. What happens is that the startup script that we manually invoked
launched the parent, root-owned process (PID 9344). It in turn launched five child
processes owned by apache (PIDs 9345–9351).
Why? Well, the idea is that the parent process does not service any request at all. Its
sole purpose is to keep an eye on the child processes. If one of them dies for any
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