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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HEAD>
<TITLE>Definitions of terms used to describe Apache directives
</TITLE>
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<H1 ALIGN="CENTER">Terms Used to Describe Apache Directives</H1>
<P>
Each Apache configuration directive is described using a common format
that looks like this:
</P>
<DL>
<DD><A
HREF="#Syntax"
REL="Help"
><STRONG>Syntax:</STRONG></A> <EM>directive-name</EM> <EM>some args</EM>
<BR>
<A
HREF="#Default"
REL="Help"
><STRONG>Default:</STRONG></A>
<SAMP><EM>directive-name default-value</EM></SAMP>
<BR>
<A
HREF="#Context"
REL="Help"
><STRONG>Context:</STRONG></A> <EM>context-list</EM>
<BR>
<A
HREF="#Override"
REL="Help"
><STRONG>Override:</STRONG></A> <EM>override</EM>
<BR>
<A
HREF="#Status"
REL="Help"
><STRONG>Status:</STRONG></A> <EM>status</EM>
<BR>
<A
HREF="#Module"
REL="Help"
><STRONG>Module:</STRONG></A> <EM>module-name</EM>
<BR>
<A
HREF="#Compatibility"
REL="Help"
><STRONG>Compatibility:</STRONG></A> <EM>compatibility notes</EM>
</DD>
</DL>
<P>
Each of the directive's attributes, complete with possible values
where possible, are described in this document.
</P>
<H2>Directive Terms</H2>
<UL>
<LI><A HREF="#Syntax">Syntax</A>
</LI>
<LI><A HREF="#Default">Default</A>
</LI>
<LI><A HREF="#Context">Context</A>
</LI>
<LI><A HREF="#Override">Override</A>
</LI>
<LI><A HREF="#Status">Status</A>
</LI>
<LI><A HREF="#Module">Module</A>
</LI>
<LI><A HREF="#Compatibility">Compatibility</A>
</LI>
</UL>
<HR>
<H2><A NAME="Syntax">Syntax</A></H2>
<P>
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
<em>emphasized</em>. Directives which can take a variable number of
arguments will end in "..." indicating that the last argument is
repeated.
</P>
<P>
Directives use a great number of different argument types.
A few common ones are defined below.</p>
<dl>
<dt><em>URL</em></dt>
<dd>A complete Uniform Resource Locator including a scheme, hostname,
and optional pathname as in
<code>http://www.example.com/path/to/file.html</code></dd>
<dt><em>URL-path</em><dt>
<dd>The part of a <em>url</em> which follows the scheme and hostname
as in <code>/path/to/file.html</code>. The <em>url-path</em>
represents a web-view of a resource, as opposed to a file-system
view.</dd>
<dt><em>file-path</em></dt>
<dd>The path to a file in the local file-system beginning with the
root directory as in
<code>/usr/local/apache/htdocs/path/to/file.html</code>. Unless
otherwise specified, a <em>file-path</em> which does not begin with a
slash will be treated as relative to the <a
href="core.html#serverroot">ServerRoot</a>.</dd>
<dt><em>directory-path</em></dt>
<dd>The path to a directory in the local file-system beginning with
the root directory as in
<code>/usr/local/apache/htdocs/path/to/</code>.
<dt><em>filename</em></dt>
<dd>The name of a file with no accompanying path information as in
<code>file.html</code>.</dd>
<dt><em>regex</em></dt>
<dd>A <a href="../misc/FAQ.html#regex">regular expression</a>, which
is a way of describing a pattern to match in text. The directive
definition will specify what the <em>regex</em> is matching
against.</dd>
<dt><em>extension</em></dt>
<dd>In general, this is the part of the <em>filename</em> which
follows the last dot. However, Apache recognizes multiple filename
extensions, so if a <em>filename</em> contains more than one dot, each
dot-separated part of the filename following the first dot is an
<em>extension</em>. For example, the <em>filename</em>
<code>file.html.en</code> contains two extensions: <code>.html</code>
and <code>.en</code>. For Apache directives, you may specify
<em>extension</em>s with or without the leading dot. In addition,
<em>extension</em>s are not case sensitive.</dd>
<dt><em>MIME-type</em></dt>
<dd>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 <code>text/html</code>.
<dt><em>env-variable</em></dt>
<dd>The name of an <a href="../env.html">environment variable</a>
defined in the Apache configuration process. Note this is not
necessarily the same as an operating system environment variable. See
the <a href="../env.html">environment variable documentation</a> for
more details.</dd>
</dl>
<HR>
<H2><A NAME="Default">Default</A></H2>
<P>
If the directive has a default value (<EM>i.e.</EM>, 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
"<EM>None</EM>". 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.
</P>
<HR>
<H2><A NAME="Context">Context</A></H2>
<P>
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:
</P>
<DL>
<DT><STRONG>server config</STRONG>
</DT>
<DD>This means that the directive may be used in the server
configuration files (<EM>e.g.</EM>, <SAMP>httpd.conf</SAMP>,
<SAMP>srm.conf</SAMP>, and <SAMP>access.conf</SAMP>), but
<STRONG>not</STRONG> within any <SAMP><VirtualHost></SAMP> or
<Directory> containers. It is not allowed in
<SAMP>.htaccess</SAMP> files at all.
<P>
</P>
</DD>
<DT><STRONG>virtual host</STRONG>
</DT>
<DD>This context means that the directive may appear inside
<SAMP><VirtualHost></SAMP> containers in the server
configuration files.
<P>
</P>
</DD>
<DT><STRONG>directory</STRONG>
</DT>
<DD>A directive marked as being valid in this context may be used
inside <SAMP><Directory></SAMP>,
<SAMP><Location></SAMP>, and <SAMP><Files></SAMP>
containers in the server configuration files, subject to the
restrictions outlined in <A HREF="../sections.html">How Directory,
Location and Files sections work</A>.
<P>
</P>
</DD>
<DT><STRONG>.htaccess</STRONG>
</DT>
<DD>If a directive is valid in this context, it means that it can
appear inside <EM>per</EM>-directory <SAMP>.htaccess</SAMP> files.
It may not be processed, though depending upon the
<A
HREF="#Override"
REL="Help"
>overrides</A>
currently active.
<P>
</P>
</DD>
</DL>
<P>
The directive is <EM>only</EM> 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 --
<EM>i.e.</EM>, the server won't even start.
</P>
<P>
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 "<SAMP>server config,
.htaccess</SAMP>" can be used in the <SAMP>httpd.conf</SAMP> file
and in <SAMP>.htaccess</SAMP> files, but not within any
<Directory> or <VirtualHost> containers.
</P>
<HR>
<H2><A NAME="Override">Override</A></H2>
<P>
This directive attribute indicates which configuration override must
be active in order for the directive to be processed when it appears
in a <SAMP>.htaccess</SAMP> file. If the directive's
<A
HREF="#Context"
REL="Help"
>context</A>
doesn't permit it to appear in <SAMP>.htaccess</SAMP> files, this
attribute should say "<EM>Not applicable</EM>".
</P>
<P>
Overrides are activated by the
<A
HREF="core.html#allowoverride"
REL="Help"
><SAMP>AllowOverride</SAMP></A>
directive, and apply to a particular scope (such as a directory) and
all descendants, unless further modified by other
<SAMP>AllowOverride</SAMP> directives at lower levels. The
documentation for that directive also lists the possible override
names available.
</P>
<HR>
<H2><A NAME="Status">Status</A></H2>
<P>
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:
</P>
<DL>
<DT><STRONG>Core</STRONG>
</DT>
<DD>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.
<P>
</P>
</DD>
<DT><STRONG>MPM</STRONG>
</DT>
<DD>A directive labeled as having "MPM" status is
provided by a <a href="../mpm.html">Multi-Processing Module</a>.
This type of directive will be available if and only if you are
using one of the MPMs lised on the <a href="#Module">Module</a>
line of the directive definition.
<P>
</P>
</DD>
<DT><STRONG>Base</STRONG>
</DT>
<DD>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.
<P>
</P>
</DD>
<DT><STRONG>Extension</STRONG>
</DT>
<DD>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.
<P>
</P>
</DD>
<DT><STRONG>Experimental</STRONG>
</DT>
<DD>"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.
<P>
</P>
</DD>
</DL>
<HR>
<H2><A NAME="Module">Module</A></H2>
<P>
This quite simply lists the name of the source module which defines
the directive.
</P>
<HR>
<H2><A NAME="Compatibility">Compatibility</A></H2>
<P>
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 behaviour between the two should also
be mentioned. Otherwise, this attribute should say "<EM>No
compatibility issues.</EM>"
</P>
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