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<p><code>.htaccess</code> files provide a way to make configuration
changes on a per-directory basis.</p>
</div>
<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#related">.htaccess files</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#what">What they are/How to use them</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#when">When (not) to use .htaccess files</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#how">How directives are applied</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#auth">Authentication example</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#ssi">Server Side Includes example</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#cgi">CGI example</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#troubleshoot">Troubleshooting</a></li>
</ul></div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="related" id="related">.htaccess files</a></h2>
<table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="../mod/core.html">core</a></code></li><li><code class="module"><a href="../mod/mod_authn_file.html">mod_authn_file</a></code></li><li><code class="module"><a href="../mod/mod_authz_groupfile.html">mod_authz_groupfile</a></code></li><li><code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code></li><li><code class="module"><a href="../mod/mod_include.html">mod_include</a></code></li><li><code class="module"><a href="../mod/mod_mime.html">mod_mime</a></code></li></ul></td><td><ul><li><code class="directive"><a href="../mod/core.html#accessfilename">AccessFileName</a></code></li><li><code class="directive"><a href="../mod/core.html#allowoverride">AllowOverride</a></code></li><li><code class="directive"><a href="../mod/core.html#options">Options</a></code></li><li><code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code></li><li><code class="directive"><a href="../mod/core.html#sethandler">SetHandler</a></code></li><li><code class="directive"><a href="../mod/mod_authn_core.html#authtype">AuthType</a></code></li><li><code class="directive"><a href="../mod/mod_authn_core.html#authname">AuthName</a></code></li><li><code class="directive"><a href="../mod/mod_authn_file.html#authuserfile">AuthUserFile</a></code></li><li><code class="directive"><a href="../mod/mod_authz_groupfile.html#authgroupfile">AuthGroupFile</a></code></li><li><code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code></li></ul></td></tr></table>
<div class="note">You should avoid using <code>.htaccess</code> files completely if you have access to
httpd main server config file. Using <code>.htaccess</code> files slows down your Apache server.
Any directive that you can include in a <code>.htaccess</code> file is better set in a <code class="directive"><a href="../mod/core.html#directory">Directory</a></code> block, as it will have the same effect with better performance.</div>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="what" id="what">What they are/How to use them</a></h2>
<p><code>.htaccess</code> files (or "distributed configuration files")
provide a way to make configuration changes on a per-directory basis. A
file, containing one or more configuration directives, is placed in a
particular document directory, and the directives apply to that
directory, and all subdirectories thereof.</p>
<div class="note"><h3>Note:</h3>
<p>If you want to call your <code>.htaccess</code> file something
else, you can change the name of the file using the <code class="directive"><a href="../mod/core.html#accessfilename">AccessFileName</a></code> directive. For example,
if you would rather call the file <code>.config</code> then you
can put the following in your server configuration file:</p>
<div class="example"><p><code>
AccessFileName .config
</code></p></div>
</div>
<p>In general, <code>.htaccess</code> files use the same syntax as
the <a href="../configuring.html#syntax">main configuration
files</a>. What you can put in these files is determined by the
<code class="directive"><a href="../mod/core.html#allowoverride">AllowOverride</a></code> directive. This
directive specifies, in categories, what directives will be
honored if they are found in a <code>.htaccess</code> file. If a
directive is permitted in a <code>.htaccess</code> file, the
documentation for that directive will contain an Override section,
specifying what value must be in <code class="directive"><a href="../mod/core.html#allowoverride">AllowOverride</a></code> in order for that
directive to be permitted.</p>
<p>For example, if you look at the documentation for the <code class="directive"><a href="../mod/core.html#adddefaultcharset">AddDefaultCharset</a></code>
directive, you will find that it is permitted in <code>.htaccess</code>
files. (See the Context line in the directive summary.) The <a href="../mod/directive-dict.html#Context">Override</a> line reads
<code>FileInfo</code>. Thus, you must have at least
<code>AllowOverride FileInfo</code> in order for this directive to be
honored in <code>.htaccess</code> files.</p>
<div class="example"><h3>Example:</h3><table>
<tr>
<td><a href="../mod/directive-dict.html#Context">Context:</a></td>
<td>server config, virtual host, directory, .htaccess</td>
</tr>
<tr>
<td><a href="../mod/directive-dict.html#Override">Override:</a></td>
<td>FileInfo</td>
</tr>
</table></div>
<p>If you are unsure whether a particular directive is permitted in a
<code>.htaccess</code> file, look at the documentation for that
directive, and check the Context line for ".htaccess".</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="when" id="when">When (not) to use .htaccess files</a></h2>
<p>In general, you should only use <code>.htaccess</code> files when
you don't have access to the main server configuration file. There is,
for example, a common misconception that user authentication should
always be done in <code>.htaccess</code> files, and, in more recent years,
another miscomception that <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> directives
must go in <code>.htaccess</code> files. This is simply not the
case. You can put user authentication configurations in the main server
configuration, and this is, in fact, the preferred way to do
things. Likewise, <code>mod_rewrite</code> directives work better,
in many respects, in the main server configuration.</p>
<p><code>.htaccess</code> files should be used in a case where the
content providers need to make configuration changes to the server on a
per-directory basis, but do not have root access on the server system.
In the event that the server administrator is not willing to make
frequent configuration changes, it might be desirable to permit
individual users to make these changes in <code>.htaccess</code> files
for themselves. This is particularly true, for example, in cases where
ISPs are hosting multiple user sites on a single machine, and want
their users to be able to alter their configuration.</p>
<p>However, in general, use of <code>.htaccess</code> files should be
avoided when possible. Any configuration that you would consider
putting in a <code>.htaccess</code> file, can just as effectively be
made in a <code class="directive"><a href="../mod/core.html#directory"><Directory></a></code> section in your main server
configuration file.</p>
<p>There are two main reasons to avoid the use of
<code>.htaccess</code> files.</p>
<p>The first of these is performance. When <code class="directive"><a href="../mod/core.html#allowoverride">AllowOverride</a></code>
is set to allow the use of <code>.htaccess</code> files, Apache will
look in every directory for <code>.htaccess</code> files. Thus,
permitting <code>.htaccess</code> files causes a performance hit,
whether or not you actually even use them! Also, the
<code>.htaccess</code> file is loaded every time a document is
requested.</p>
<p>Further note that Apache must look for <code>.htaccess</code> files
in all higher-level directories, in order to have a full complement of
directives that it must apply. (See section on <a href="#how">how
directives are applied</a>.) Thus, if a file is requested out of a
directory <code>/www/htdocs/example</code>, Apache must look for the
following files:</p>
<div class="example"><p><code>
/.htaccess<br />
/www/.htaccess<br />
/www/htdocs/.htaccess<br />
/www/htdocs/example/.htaccess
</code></p></div>
<p>And so, for each file access out of that directory, there are 4
additional file-system accesses, even if none of those files are
present. (Note that this would only be the case if
<code>.htaccess</code> files were enabled for <code>/</code>, which
is not usually the case.)</p>
<p>In the case of <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directives, in
<code>.htaccess</code> context these regular expressions must be
re-compiled with every request to the directory, whereas in main
server configuration context they are compiled once and cached.
Additionally, the rules themselves are more complicated, as one must
work around the restrictions that come with per-directory context
and <code>mod_rewrite</code>. Consult the <a href="../rewrite/intro.html#htaccess">Rewrite Guide</a> for more
detail on this subject.</p>
<p>The second consideration is one of security. You are permitting
users to modify server configuration, which may result in changes over
which you have no control. Carefully consider whether you want to give
your users this privilege. Note also that giving users less
privileges than they need will lead to additional technical support
requests. Make sure you clearly tell your users what level of
privileges you have given them. Specifying exactly what you have set
<code class="directive"><a href="../mod/core.html#allowoverride">AllowOverride</a></code> to, and pointing them
to the relevant documentation, will save yourself a lot of confusion
later.</p>
<p>Note that it is completely equivalent to put a <code>.htaccess</code>
file in a directory <code>/www/htdocs/example</code> containing a
directive, and to put that same directive in a Directory section
<code><Directory /www/htdocs/example></code> in your main server
configuration:</p>
<p><code>.htaccess</code> file in <code>/www/htdocs/example</code>:</p>
<div class="example"><h3>Contents of .htaccess file in
<code>/www/htdocs/example</code></h3><p><code>
AddType text/example .exm
</code></p></div>
<div class="example"><h3>Section from your <code>httpd.conf</code>
file</h3><p><code>
<Directory /www/htdocs/example><br />
<span class="indent">
AddType text/example .exm<br />
</span>
</Directory>
</code></p></div>
<p>However, putting this configuration in your server configuration
file will result in less of a performance hit, as the configuration is
loaded once when Apache starts, rather than every time a file is
requested.</p>
<p>The use of <code>.htaccess</code> files can be disabled completely
by setting the <code class="directive"><a href="../mod/core.html#allowoverride">AllowOverride</a></code>
directive to <code>none</code>:</p>
<div class="example"><p><code>
AllowOverride None
</code></p></div>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="how" id="how">How directives are applied</a></h2>
<p>The configuration directives found in a <code>.htaccess</code> file
are applied to the directory in which the <code>.htaccess</code> file
is found, and to all subdirectories thereof. However, it is important
to also remember that there may have been <code>.htaccess</code> files
in directories higher up. Directives are applied in the order that they
are found. Therefore, a <code>.htaccess</code> file in a particular
directory may override directives found in <code>.htaccess</code> files
found higher up in the directory tree. And those, in turn, may have
overridden directives found yet higher up, or in the main server
configuration file itself.</p>
<p>Example:</p>
<p>In the directory <code>/www/htdocs/example1</code> we have a
<code>.htaccess</code> file containing the following:</p>
<div class="example"><p><code>
Options +ExecCGI
</code></p></div>
<p>(Note: you must have "<code>AllowOverride Options</code>" in effect
to permit the use of the "<code class="directive"><a href="../mod/core.html#options">Options</a></code>" directive in
<code>.htaccess</code> files.)</p>
<p>In the directory <code>/www/htdocs/example1/example2</code> we have
a <code>.htaccess</code> file containing:</p>
<div class="example"><p><code>
Options Includes
</code></p></div>
<p>Because of this second <code>.htaccess</code> file, in the directory
<code>/www/htdocs/example1/example2</code>, CGI execution is not
permitted, as only <code>Options Includes</code> is in effect, which
completely overrides any earlier setting that may have been in
place.</p>
<h3><a name="merge" id="merge">Merging of .htaccess with the main
configuration files</a></h3>
<p>As discussed in the documentation on <a href="../sections.html">Configuration Sections</a>,
<code>.htaccess</code> files can override the <code class="directive"><a href="../mod/core.html#directory"><Directory></a></code> sections for
the corresponding directory, but will be overriden by other types
of configuration sections from the main configuration files. This
fact can be used to enforce certain configurations, even in the
presence of a liberal <code class="directive"><a href="../mod/core.html#allowoverride">AllowOverride</a></code> setting. For example, to
prevent script execution while allowing anything else to be set in
<code>.htaccess</code> you can use:</p>
<div class="example"><p><code>
<Directory /www/htdocs><br />
<span class="indent">
Allowoverride All<br />
</span>
</Directory><br />
<br />
<Location /><br />
<span class="indent">
Options +IncludesNoExec -ExecCGI<br />
</span>
</Location>
</code></p></div>
<div class="note">This example assumes that your <code class="directive"><a href="../mod/core.html#documentroot">DocumentRoot</a></code> is <code>/www/htdocs</code>.</div>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="auth" id="auth">Authentication example</a></h2>
<p>If you jumped directly to this part of the document to find out how
to do authentication, it is important to note one thing. There is a
common misconception that you are required to use
<code>.htaccess</code> files in order to implement password
authentication. This is not the case. Putting authentication directives
in a <code class="directive"><a href="../mod/core.html#directory"><Directory></a></code>
section, in your main server configuration file, is the preferred way
to implement this, and <code>.htaccess</code> files should be used only
if you don't have access to the main server configuration file. See <a href="#when">above</a> for a discussion of when you should and should
not use <code>.htaccess</code> files.</p>
<p>Having said that, if you still think you need to use a
<code>.htaccess</code> file, you may find that a configuration such as
what follows may work for you.</p>
<p><code>.htaccess</code> file contents:</p>
<div class="example"><p><code>
AuthType Basic<br />
AuthName "Password Required"<br />
AuthUserFile /www/passwords/password.file<br />
AuthGroupFile /www/passwords/group.file<br />
Require Group admins
</code></p></div>
<p>Note that <code>AllowOverride AuthConfig</code> must be in effect
for these directives to have any effect.</p>
<p>Please see the <a href="auth.html">authentication tutorial</a> for a
more complete discussion of authentication and authorization.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="ssi" id="ssi">Server Side Includes example</a></h2>
<p>Another common use of <code>.htaccess</code> files is to enable
Server Side Includes for a particular directory. This may be done with
the following configuration directives, placed in a
<code>.htaccess</code> file in the desired directory:</p>
<div class="example"><p><code>
Options +Includes<br />
AddType text/html shtml<br />
AddHandler server-parsed shtml
</code></p></div>
<p>Note that <code>AllowOverride Options</code> and <code>AllowOverride
FileInfo</code> must both be in effect for these directives to have any
effect.</p>
<p>Please see the <a href="ssi.html">SSI tutorial</a> for a more
complete discussion of server-side includes.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="cgi" id="cgi">CGI example</a></h2>
<p>Finally, you may wish to use a <code>.htaccess</code> file to permit
the execution of CGI programs in a particular directory. This may be
implemented with the following configuration:</p>
<div class="example"><p><code>
Options +ExecCGI<br />
AddHandler cgi-script cgi pl
</code></p></div>
<p>Alternately, if you wish to have all files in the given directory be
considered to be CGI programs, this may be done with the following
configuration:</p>
<div class="example"><p><code>
Options +ExecCGI<br />
SetHandler cgi-script
</code></p></div>
<p>Note that <code>AllowOverride Options</code> and <code>AllowOverride
FileInfo</code> must both be in effect for these directives to have any
effect.</p>
<p>Please see the <a href="cgi.html">CGI tutorial</a> for a more
complete discussion of CGI programming and configuration.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="troubleshoot" id="troubleshoot">Troubleshooting</a></h2>
<p>When you put configuration directives in a <code>.htaccess</code>
file, and you don't get the desired effect, there are a number of
things that may be going wrong.</p>
<p>Most commonly, the problem is that <code class="directive"><a href="../mod/core.html#allowoverride">AllowOverride</a></code> is not
set such that your configuration directives are being honored. Make
sure that you don't have a <code>AllowOverride None</code> in effect
for the file scope in question. A good test for this is to put garbage
in your <code>.htaccess</code> file and reload the page. If a server error is
not generated, then you almost certainly have <code>AllowOverride
None</code> in effect.</p>
<p>If, on the other hand, you are getting server errors when trying to
access documents, check your Apache error log. It will likely tell you
that the directive used in your <code>.htaccess</code> file is not
permitted.</p>
<div class="example"><p><code>
[Fri Sep 17 18:43:16 2010] [alert] [client 192.168.200.51] /var/www/html/.htaccess: DirectoryIndex not allowed here
</code></p></div>
<p>This will indicate either that you've used a directive that is
never permitted in <code>.htaccess</code> files, or that you simply
don't have <code class="directive"><a href="../mod/core.html#allowoverride">AllowOverride</a></code> set to
a level sufficient for the directive you've used. Consult the
documentation for that particular directive to determine which is
the case.</p>
<p>Alternately, it may tell you that you had a syntax error in your
usage of the directive itself.</p>
<div class="example"><p><code>
[Sat Aug 09 16:22:34 2008] [alert] [client 192.168.200.51] /var/www/html/.htaccess: RewriteCond: bad flag delimiters
</code></p></div>
<p>In this case, the error message should be specific to the
particular syntax error that you have committed.</p>
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