All about Apache Config File
Apache is configured by placing directives in plain text configuration files. The main configuration file is usually called
httpd.conf
The location of this file is set at compile-time, but may be overridden with the -f command line flag. Some sites also have srm.conf and access.conf files for historical reasons. In addition, other configuration files may be added using the Include directive. Any directive may be placed in any of these configuration files.
Changes to the main configuration files are only recognized by Apache when it is started or restarted.
New with Apache 1.3.13 is a feature where if any configuration file is actually a directory, Apache will enter that directory and parse any files (and subdirectories) found there as configuration files. One possible use for this would be to add VirtualHosts by creating small configuration files for each host, and placing them in such a configuration directory. Thus, you can add or remove VirtualHosts without editing any files at all, simply adding or deleting them. This makes automating such processes much easier. The server also reads a file containing mime document types; the filename is set by the TypesConfig directive, and is mime.types by default.
Syntax of the Configuration Files
Apache configuration files contain one directive per line. The back-slash "\" may be used as the last character on a line to indicate that the directive continues onto the next line. There must be no other characters or white space between the back-slash and the end of the line.
Directives in the configuration files are case-insensitive, but arguments to directives are often case sensitive. Lines which begin with the hash character "#" are considered comments, and are ignored. Comments may not be included on a line after a configuration directive. Blank lines and white space occurring before a directive are ignored, so you may indent directives for clarity.
You can check your configuration files for syntax errors without starting the server by using
apachectl configtest or the -t command line option.
root@host1:[/usr/apache2/2.2/bin]#./apachectl configtest
Syntax OK
root@host1:[/usr/apache2/2.2/bin]#
Modules
Related Modules : mod_so
Related Directives :
AddModule
ClearModuleList
<IfModule>
LoadModule
Apache is a modular server. This implies that only the most basic functionality is included in the core server. Extended features are available through modules which can be loaded into Apache. By default, a base set of modules is included in the server at compile-time. If the server is compiled to use dynamically loaded modules, then modules can be compiled separately and added at any time using the LoadModule directive. Otherwise, Apache must be recompiled to add or remove modules. Configuration directives may be included conditional on a presence of a particular module by enclosing them in an <IfModule> block.
To see which modules are currently compiled into the server, you can use the -l command line option.
root@host1:[/usr/apache2/2.2/bin]#./apachectl -l
Compiled in modules:
core.c
prefork.c
http_core.c
mod_so.c
root@host1:[/usr/apache2/2.2/bin]#
<IfModule> directive
Syntax: <IfModule [!]module-name> ... </IfModule>
Default: None
Context: all
Status: Core
Compatibility: IfModule is only available in 1.2 and later.
The <IfModule test>...</IfModule> section is used to mark directives that are conditional. The directives within an IfModule section are only processed if the test is true. If test is false, everything between the start and end markers is ignored.
The test in the <IfModule> section directive can be one of two forms:
* module name
* !module name
In the former case, the directives between the start and end markers are only processed if the module named module name is included in Apache -- either compiled in or dynamically loaded using LoadModule. The second format reverses the test, and only processes the directives if module name is not included. The module name argument is the file name of the module, at the time it was compiled. For example, mod_rewrite.c. <IfModule> sections are nest-able, which can be used to implement simple multiple-module tests.
Scope of Directives
Related Directives:
<Directory>
<DirectoryMatch>
<Files>
<FilesMatch>
<Location>
<LocationMatch>
<VirtualHost>
Directives placed in the main configuration files apply to the entire server. If you wish to change the configuration for only a part of the server, you can scope your directives by placing them in <Directory>, <DirectoryMatch>, <Files>, <FilesMatch>, <Location>, and <LocationMatch> sections. These sections limit the application of the directives which they enclose to particular filesystem locations or URLs. They can also be nested, allowing for very fine grained configuration. Apache has the capability to serve many different websites simultaneously. This is called Virtual Hosting. Directives can also be scoped by placing them inside <VirtualHost> sections, so that they will only apply to requests for a particular website.
Although most directives can be placed in any of these sections, some directives do not make sense in some contexts. For example, directives controlling process creation can only be placed in the main server context. To find which directives can be placed in which sections, check the Context of the directive. For further information, we provide details on How Directory, Location and Files sections work.
.htaccess Files
Related Directives :
AccessFileName
AllowOverride
Apache allows for decentralized management of configuration via special files placed inside the web tree. The special files are usually called .htaccess, but any name can be specified in the AccessFileName directive. Directives placed in .htaccess files apply to the directory where you place the file, and all sub-directories. The .htaccess files follow the same syntax as the main configuration files. Since .htaccess files are read on every request, changes made in these files take immediate effect.
To find which directives can be placed in .htaccess files, check the Context of the directive. The server administrator further controls what directives may be placed in .htaccess files by configuring the AllowOverride directive in the main configuration files.
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