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Apache HTTP Server Version 1.3
Terms Used to Describe Apache Directives
Each Apache configuration directive is described using a common format that looks like
this:
- Syntax: directive-name some
args
Default: directive-name
default-value
Context: context-list
Override: override
Status: status
Module: module-name
Compatibility: compatibility
notes
Each of the directive's attributes, complete with possible values where possible, are
described in this document.
Directive Terms
This indicates the format of the directive as it would appear in a configuration file. This
syntax is extremely directive-specific, and is described in detail in the directive's
definition. Generally, the directive name is followed by a series of one or more
space-separated arguments. If an argument contains a space, the argument must be enclosed in
double quotes. Optional arguments are enclosed in square brackets. Where an argument can take
on more than one possible value, the possible values are separated by vertical bars
"|". Literal text is presented in the default font, while argument-types for which
substitution is necessary are emphasized. Directives which can take a variable number
of arguments will end in "..." indicating that the last argument is repeated.
Directives use a great number of different argument types. A few common ones are defined
below.
- URL
- A complete Uniform Resource Locator including a scheme, hostname, and optional pathname
as in
http://www.example.com/path/to/file.html
- URL-path
- The part of a url which follows the scheme and hostname as in
/path/to/file.html.
The url-path represents a web-view of a resource, as opposed to a file-system
view.
- file-path
- The path to a file in the local file-system beginning with the root directory as in
/usr/local/apache/htdocs/path/to/file.html.
Unless otherwise specified, a file-path which does not begin with a slash will be
treated as relative to the ServerRoot.
- directory-path
- The path to a directory in the local file-system beginning with the root directory as in
/usr/local/apache/htdocs/path/to/.
- filename
- The name of a file with no accompanying path information as in
file.html.
- regex
- A regular expression,
which is a way of describing a pattern to match in text. The directive definition will
specify what the regex is matching against.
- extension
- In general, this is the part of the filename which follows the last dot.
However, Apache recognizes multiple filename extensions, so if a filename
contains more than one dot, each dot-separated part of the filename following the first
dot is an extension. For example, the filename
file.html.en
contains two extensions: .html and .en. For Apache directives,
you may specify extensions with or without the leading dot. In addition, extensions
are not case sensitive.
- MIME-type
- A method of describing the format of a file which consists of a major format type and a
minor format type, separated by a slash as in
text/html.
- env-variable
- The name of an environment variable
defined in the Apache configuration process. Note this is not necessarily the same as an
operating system environment variable. See the
environment variable documentation for
more details.
If the directive has a default value (i.e., if you omit it from your configuration
entirely, the Apache Web server will behave as though you set it to a particular value), it is
described here. If there is no default value, this section should say "None".
Note that the default listed here is not necessarily the same as the value the directive takes
in the default httpd.conf distributed with the server.
This indicates where in the server's configuration files the directive is legal. It's a
comma-separated list of one or more of the following values:
- server config
- This means that the directive may be used in the server configuration files (e.g.,
httpd.conf, srm.conf, and access.conf), but not
within any <VirtualHost> or <Directory> containers. It is not
allowed in .htaccess files at all.
- virtual host
- This context means that the directive may appear inside <VirtualHost>
containers in the server configuration files.
- directory
- A directive marked as being valid in this context may be used inside <Directory>,
<Location>, and <Files> containers in the server
configuration files, subject to the restrictions outlined in
How Directory, Location and Files
sections work.
- .htaccess
- If a directive is valid in this context, it means that it can appear inside per-directory
.htaccess files. It may not be processed, though depending upon the
overrides currently active.
The directive is only allowed within the designated context; if you try to use it
elsewhere, you'll get a configuration error that will either prevent the server from handling
requests in that context correctly, or will keep the server from operating at all -- i.e.,
the server won't even start.
The valid locations for the directive are actually the result of a Boolean OR of all of the
listed contexts. In other words, a directive that is marked as being valid in "server
config, .htaccess" can be used in the httpd.conf file and in .htaccess
files, but not within any <Directory> or <VirtualHost> containers.
This directive attribute indicates which configuration override must be active in order for
the directive to be processed when it appears in a .htaccess file. If the
directive's context doesn't permit it to appear in .htaccess
files, this attribute should say "Not applicable".
Overrides are activated by the
AllowOverride
directive, and apply to a particular scope (such as a directory) and all descendants, unless
further modified by other AllowOverride directives at lower levels. The
documentation for that directive also lists the possible override names available.
This indicates how tightly bound into the Apache Web server the directive is; in other
words, you may need to recompile the server with an enhanced set of modules in order to gain
access to the directive and its functionality. Possible values for this attribute are:
- Core
- If a directive is listed as having "Core" status, that means it is part of the
innermost portions of the Apache Web server, and is always available.
- Base
- A directive labeled as having "Base" status is supported by one of the
standard Apache modules which is compiled into the server by default, and is therefore
normally available unless you've taken steps to remove the module from your configuration.
- Extension
- A directive with "Extension" status is provided by one of the modules included
with the Apache server kit, but the module isn't normally compiled into the server. To
enable the directive and its functionality, you will need to change the server build
configuration files and re-compile Apache.
- Experimental
- "Experimental" status indicates that the directive is available as part of the
Apache kit, but you're on your own if you try to use it. The directive is being documented
for completeness, and is not necessarily supported. The module which provides the
directive may or may not be compiled in by default; check the top of the page which
describes the directive and its module to see if it remarks on the availability.
This quite simply lists the name of the source module which defines the directive.
If the directive wasn't part of the original Apache version 1 distribution, the version in
which it was introduced should be listed here. If the directive has the same name as one from
the NCSA HTTPd server, any inconsistencies in behavior between the two should also be
mentioned. Otherwise, this attribute should say "No compatibility issues."
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