The configuration file

French | Spanish | Portuguese | Italian | German | Japanese | Chinese | Korean | Russian | Arabic

If you are running your own Linux system, you can install Apache as a standard httpd daemon server that will use port 80. (You have to do the installation when logged in as the system’s administrator – root account.) You will need to create user and group accounts for your web server (as described in your Linux manuals); the usernames ‘www’ or ‘nobody’ are conventional. The user entry that you create in your /etc/password file should be appropriate for a server – no password (so it is not possible to login on this account), and the shell set to /bin/false. The user and group number that you select have to be specified in the httpd.conf file. If you are only planning to play with Apache for learning purposes, you will find it easier to run Apache under one of your existing user identifiers with the server monitoring port 8080. The configure script, in /home/me/apache_1.3.27, allows you to define the Apache that you want. The script can be run, from the /home/me/apache_1.3.27 directory, as:

./configure --help

Running the script with the --help command line parameter results in a listing of all the configuration options. In the disable-module part of this listing there is a table whose contents define the Apache that will be built by default. This table lists all the modules whose code is included in this Apache release and indicates whether they will be incorporated in the built version. The table data should be something like the following:

access=yes actions=yes alias=yes
   asis=yes auth=yes auth_anon=no
   auth_db=no auth_dbm=no auth_digest=no
   autoindex=yes cern_meta=no cgi=yes
   digest=no dir=yes env=yes
   example=no expires=no headers=no
   imap=yes include=yes info=no
   log_agent=no log_config=yes log_referer=no
   mime=yes mime_magic=no mmap_static=no
   negotiation=yes proxy=no rewrite=no
   setenvif=yes so=no speling=no
   status=yes unique_id=no userdir=yes
   usertrack=no vhost_alias=no

(Documentation relating to each of these modules is available in the manual subdirectory of your installation, or online at http://httpd.apache.org/docs/mod/.) Modules that are not included by default can be added, and default modules may be dropped. When you have chosen the modules that you require, you can run the configure script with command line arguments that specify the directory where the working Apache system is to be created and specifying your changes to the default module list. For example, the following command would identify the /local/apache directory as the location where the web server system should be installed, drop support for user directories with web resources, and enable HTTP authorization with the dbm system being used to store username and password data.

./configure --prefix=/local/apache \
   --disable-module=userdir \
 --enable-module=auth_dbm

(If you were creating an ‘official’ Apache on Linux, you would define additional options such as the account and group under which the server is to run.) There are many other options that can be used to change things such as the location of the logs directory, or the cache files for a proxy server. The next two steps are:

make
 make install

The first does all the compilation and linkage of executables; the second copies files and directories into your deployment directory (as specified via the --prefix argument for the configure script) which for these examples is /local/apache. The /local/apache directory on a Linux/Unix system should contain:

bin

The directory with the httpd executable, support programs like htpasswd, and scripts.

cgi-bin

This should contain two demonstration scripts (perl and sh) that echo environment variables (you may find it necessary to change the access permissions for these files before you can run the scripts).

htdocs

– A welcome page in several European languages.

– Subdirectory with Apache manual.

conf

Configuration files.

The configuration files include the httpd.conf file along with an original unedited distribution version (http.conf.default). The httpd.conf file has changes such as the inclusion of data defining the actual installation directories, and other adjustments that reflect the options chosen at the configuration stage. While there are many options in the configuration file that you will want to change, the installed system should be capable of being run directly. The ‘out-of-the-box’ configured Apache can be run by:

On Windows: Start/Programs/Apache Web Server/Start Apache

On Linux/Unix: /local/apache/bin/apachectl start

When your Apache has started, you can contact it via a browser aimed at http:// localhost or http//localhost:8080. Apache should display a welcome page. This is actually a demonstration of HTTP content negotiation; there are several versions of the welcome page in different languages. If you exit your browser, restart it and set a language preference and then again contact your Apache, you should be able to get versions of the welcome page in French, Spanish, Italian etc. You should also be able to test run the CGI programs printenv (a Perl script) and test-cgi: http://localhost:8080/cgi-bin/test-cgi (if these demonstration CGI programs don’t run, check the access and execution permissions as set in the cgi-bin directory). On Linux/Unix, you can view the processes that are running using the command ps -ef | fgrep httpd (the ps command gets a listing of all processes, the fgrep filter picks those running the httpd executable). This should show ten processes running Apaches for you (a chief and nine tribesmen). The number is determined by default parameters in the httpd.conf file. You should shut down your Apache tribe before experimenting with changes to the settings in the httpd.conf file. Your Apache process group can be closed down via the Linux/Unix command /local/apache/bin/apachectl stop, or via the Stop Apache option in the Windows popup menu. On Linux/Unix, it is possible to change the configuration file and get Apache to change over to the new settings without requiring a full shutdown. If you use the apachectl restart command, the Apache chief reads the new options; it terminates all tribesmen and creates new ones that work with the new options (any working tribesmen are allowed to finish their current activities before they are terminated).

An httpd.conf file consists of directives interspersed amongst a lot of explanatory comment. The possible directives are documented at http://httpd.apache.org/docs/mod/ directives.html. Some directives are simple one line commands, like the AddHandler directive that notifies Apache that files with a particular extension have to be processed in some special manner (via a ‘Handler’):

AddHandler cgi-script .cgi

Other directives, like the Directory directive, take multiple subdirectives. These directives have a start directive tag, a body and an end directive tag:

<Directory "/local/apache/htdocs">
   Options Indexes FollowSymLinks MultiViews
   AllowOverride None
   Order allow, deny
   Allow from all
 </Directory>

Their effect is to limit the scope of the grouped subdirectives. You should read through the auto-generated httpd.conf file prior to attempting any changes. The first few directives set the global environment for your Apache tribe. The first important directive is the one that specifies the installation directory, e.g.

ServerRoot "C:/Program Files/Apache Group/Apache"

(Irrespective of platform, Apache code uses “/” as the separator character for directory pathnames.) The installer program will have filled in the value for ServerRoot. The next two directives identify files used for housekeeping data – such as the scoreboard file that is employed on systems that don’t support shared memory segments. The next few directives set values for controls such as the timeouts on connections, and limits on the number of requests a child process can handle. The Linux/Unix file will have directives that set the limits on the number of server processes, number to create at startup etc.; the Windows configuration file will simply have a limit on the number of threads in the second process (this is effectively the equivalent to the MaxClients control). If you will be running your Apache system on a typical home PC (Linux orWindows OSs), you will probably want to reduce the values for all those parameters. The Linux/Unix file next contains a single example related to the setting up of shared objects – dynamic linking in the Unix world. The corresponding part in the Windows httpd.conf file is longer; it has commented out LoadModule directives for important optional modules. For example, if you want to support requests concerning the server status, you should uncomment the LoadModule status_module directive. The next group of directives, starting with the Port 80 directive, set parameters for the Apache chief. If you are setting up a real httpd process on Linux, you may need to change the values in the User and Group directives, and you will also need to specify your email address in the ServerAdmin directive. These directives can be ignored if you are simply running a toy Apache system for learning purposes. If you are setting up a real Apache server, you will also need DNS set up; toy servers can be run with the ServerName directive specifying 127.0.0.1 or localhost. The next few directives specify the locations of components like the main directories used for HTML documents and CGI programs. They also set default access permissions that will apply to all directories unless specifically overridden by subsequent directives (as added by you). The main example here is for the htdocs directory; this should be something like:

<Directory "C:/Program Files/Apache Group/Apache/htdocs">
   Options Indexes FollowSymLinks MultiViews
   AllowOverride None
   Order allow, deny
   Allow from all
 </Directory>

Directory, File and Location directives group other directives. The Options directive allows for the following controls:

All

Enable all options except MultiViews.

ExecCGI

Allow execution of CGI scripts in this directory (location).

Includes, IncludesNoEXEC

Enable processing of server-side includes for appropriate files in this directory.

Indexes

If user requests a directory, and there is no suitable directory index file (whose name would be defined elsewhere using a DirectoryIndex directive), then a list of files should be returned.

MultiViews

Enables content negotiation.

FollowSymLinks, SymLinksIfOwnersMatch

Enable the use of ‘links’ in a Unix file system.

In this example, the defaults for htdocs and its subdirectories are set to allow clients to view the contents of a directory (as a page with a list of files, or something prettier), enable support for content negotiation, and permit the use of Unix inter-directory links.