disables the echo server.</p>
<example><title>Example</title>
+ <highlight language="config">
ProtocolEcho On
+ </highlight>
</example>
</usage>
<program>httpd</program> process.</p>
<example><title>Example</title>
+ <highlight language="config">
PassEnv LD_LIBRARY_PATH
+ </highlight>
</example>
</usage>
</directivesynopsis>
HTTP Server modules, and passed on to CGI scripts and SSI pages.</p>
<example><title>Example</title>
+ <highlight language="config">
SetEnv SPECIAL_PATH /foo/bin
+ </highlight>
</example>
<note><p>The internal environment variables set by this directive are set
on to CGI scripts and SSI pages.</p>
<example><title>Example</title>
+ <highlight language="config">
UnsetEnv LD_LIBRARY_PATH
+ </highlight>
</example>
</usage>
</directivesynopsis>
<p>To activate the example module, include a block similar to
the following in your <code>httpd.conf</code> file:</p>
-<example>
- <Location /example-info><br />
- SetHandler example-handler<br />
- </Location>
-</example>
+<highlight language="config">
+<Location /example-info>
+ SetHandler example-handler
+</Location>
+</highlight>
<p>As an alternative, you can put the following into a <a
href="core.html#accessfilename"><code>.htaccess</code></a> file
and then request the file "test.example" from that location:</p>
-<example>
+<highlight language="config">
AddHandler example-handler .example
-</example>
+</highlight>
<p>After reloading/restarting your server, you should be able
to browse to this location and see the brief display mentioned
<directive module="mod_expires">ExpiresByType</directive> directives
can also be defined in a more readable syntax of the form:</p>
- <example>
- ExpiresDefault "<var>base</var> [plus <var>num</var> <var>type</var>]
- [<var>num</var> <var>type</var>] ..."<br />
- ExpiresByType type/encoding "<var>base</var> [plus <var>num</var> <var>type</var>]
- [<var>num</var> <var>type</var>] ..."
- </example>
+ <highlight language="config">
+ExpiresDefault "<var>base</var> [plus <var>num</var> <var>type</var>] [<var>num</var> <var>type</var>] ..."
+ExpiresByType type/encoding "<var>base</var> [plus <var>num</var> <var>type</var>] [<var>num</var> <var>type</var>] ..."
+ </highlight>
<p>where <var>base</var> is one of:</p>
make documents expire 1 month after being accessed, by
default:</p>
- <example>
- ExpiresDefault "access plus 1 month"<br />
- ExpiresDefault "access plus 4 weeks"<br />
- ExpiresDefault "access plus 30 days"
- </example>
+ <highlight language="config">
+ExpiresDefault "access plus 1 month"
+ExpiresDefault "access plus 4 weeks"
+ExpiresDefault "access plus 30 days"
+ </highlight>
<p>The expiry time can be fine-tuned by adding several
'<var>num</var> <var>type</var>' clauses:</p>
- <example>
- ExpiresByType text/html "access plus 1 month 15
- days 2 hours"<br />
- ExpiresByType image/gif "modification plus 5 hours 3
- minutes"
- </example>
+ <highlight language="config">
+ExpiresByType text/html "access plus 1 month 15 days 2 hours"
+ExpiresByType image/gif "modification plus 5 hours 3 minutes"
+ </highlight>
<p>Note that if you use a modification date based setting, the
Expires header will <strong>not</strong> be added to content
repeatedly within a relatively short timespan).</p>
<example><title>Example:</title>
- # enable expirations<br />
- ExpiresActive On<br />
- # expire GIF images after a month in the client's cache<br />
- ExpiresByType image/gif A2592000<br />
- # HTML documents are good for a week from the<br />
- # time they were changed<br />
- ExpiresByType text/html M604800
+ <highlight language="config">
+# enable expirations
+ExpiresActive On
+# expire GIF images after a month in the client's cache
+ExpiresByType image/gif A2592000
+# HTML documents are good for a week from the
+# time they were changed
+ExpiresByType text/html M604800
+ </highlight>
</example>
<p>Note that this directive only has effect if
<section id="examples"><title>Examples</title>
<section><title>Generating HTML from some other type of response</title>
- <example>
- # mod_ext_filter directive to define a filter<br />
- # to HTML-ize text/c files using the external<br />
- # program /usr/bin/enscript, with the type of<br />
- # the result set to text/html<br />
- ExtFilterDefine c-to-html mode=output \<br />
- <indent>
- intype=text/c outtype=text/html \<br />
- cmd="/usr/bin/enscript --color -W html -Ec -o - -"<br />
- </indent>
- <br />
- <Directory "/export/home/trawick/apacheinst/htdocs/c"><br />
- <indent>
- # core directive to cause the new filter to<br />
- # be run on output<br />
- SetOutputFilter c-to-html<br />
- <br />
- # mod_mime directive to set the type of .c<br />
- # files to text/c<br />
- AddType text/c .c<br />
- <br />
- </indent>
- </Directory>
- </example>
+ <highlight language="config">
+# mod_ext_filter directive to define a filter
+# to HTML-ize text/c files using the external
+# program /usr/bin/enscript, with the type of
+# the result set to text/html
+ExtFilterDefine c-to-html mode=output \
+ intype=text/c outtype=text/html \
+ cmd="/usr/bin/enscript --color -W html -Ec -o - -"
+
+<Directory "/export/home/trawick/apacheinst/htdocs/c">
+ # core directive to cause the new filter to
+ # be run on output
+ SetOutputFilter c-to-html
+
+ # mod_mime directive to set the type of .c
+ # files to text/c
+ AddType text/c .c
+</Directory>
+ </highlight>
</section>
<section><title>Implementing a content encoding filter</title>
Please refer to <module>mod_deflate</module> for a practical
implementation.</p>
- <example>
- # mod_ext_filter directive to define the external filter<br />
- ExtFilterDefine gzip mode=output cmd=/bin/gzip<br />
- <br />
- <Location /gzipped><br />
- <indent>
- # core directive to cause the gzip filter to be<br />
- # run on output<br />
- SetOutputFilter gzip<br />
- <br />
- # mod_header directive to add<br />
- # "Content-Encoding: gzip" header field<br />
- Header set Content-Encoding gzip<br />
- </indent>
- </Location>
- </example>
+ <highlight language="config">
+# mod_ext_filter directive to define the external filter
+ExtFilterDefine gzip mode=output cmd=/bin/gzip
+
+<Location /gzipped>
+
+ # core directive to cause the gzip filter to be
+ # run on output
+ SetOutputFilter gzip
+
+ # mod_header directive to add
+ # "Content-Encoding: gzip" header field
+ Header set Content-Encoding gzip
+</Location>
+ </highlight>
</section>
<section><title>Slowing down the server</title>
- <example>
- # mod_ext_filter directive to define a filter<br />
- # which runs everything through cat; cat doesn't<br />
- # modify anything; it just introduces extra pathlength<br />
- # and consumes more resources<br />
- ExtFilterDefine slowdown mode=output cmd=/bin/cat \<br />
- <indent>
- preservescontentlength<br />
- </indent>
- <br />
- <Location /><br />
- <indent>
- # core directive to cause the slowdown filter to<br />
- # be run several times on output<br />
- #<br />
- SetOutputFilter slowdown;slowdown;slowdown<br />
- </indent>
- </Location>
- </example>
+ <highlight language="config">
+# mod_ext_filter directive to define a filter
+# which runs everything through cat; cat doesn't
+# modify anything; it just introduces extra pathlength
+# and consumes more resources
+ExtFilterDefine slowdown mode=output cmd=/bin/cat \
+ preservescontentlength
+
+<Location />
+ # core directive to cause the slowdown filter to
+ # be run several times on output
+ #
+ SetOutputFilter slowdown;slowdown;slowdown
+</Location>
+ </highlight>
</section>
<section><title>Using sed to replace text in the response</title>
- <example>
- # mod_ext_filter directive to define a filter which<br />
- # replaces text in the response<br />
- #<br />
- ExtFilterDefine fixtext mode=output intype=text/html \<br />
- <indent>
- cmd="/bin/sed s/verdana/arial/g"<br />
- </indent>
- <br />
- <Location /><br />
- <indent>
- # core directive to cause the fixtext filter to<br />
- # be run on output<br />
- SetOutputFilter fixtext<br />
- </indent>
- </Location>
- </example>
+ <highlight language="config">
+# mod_ext_filter directive to define a filter which
+# replaces text in the response
+#
+ExtFilterDefine fixtext mode=output intype=text/html \
+ cmd="/bin/sed s/verdana/arial/g"
+
+<Location />
+ # core directive to cause the fixtext filter to
+ # be run on output
+ SetOutputFilter fixtext
+</Location>
+ </highlight>
</section>
<section><title>Tracing another filter</title>
- <example>
- # Trace the data read and written by mod_deflate<br />
- # for a particular client (IP 192.168.1.31)<br />
- # experiencing compression problems.<br />
- # This filter will trace what goes into mod_deflate.<br />
- ExtFilterDefine tracebefore \<br />
- <indent>
- cmd="/bin/tracefilter.pl /tmp/tracebefore" \<br />
- EnableEnv=trace_this_client<br />
- </indent>
- <br />
- # This filter will trace what goes after mod_deflate.<br />
- # Note that without the ftype parameter, the default<br />
- # filter type of AP_FTYPE_RESOURCE would cause the<br />
- # filter to be placed *before* mod_deflate in the filter<br />
- # chain. Giving it a numeric value slightly higher than<br />
- # AP_FTYPE_CONTENT_SET will ensure that it is placed<br />
- # after mod_deflate.<br />
- ExtFilterDefine traceafter \<br />
- <indent>
- cmd="/bin/tracefilter.pl /tmp/traceafter" \<br />
- EnableEnv=trace_this_client ftype=21<br />
- </indent>
- <br />
- <Directory /usr/local/docs><br />
- <indent>
- SetEnvIf Remote_Addr 192.168.1.31 trace_this_client<br />
- SetOutputFilter tracebefore;deflate;traceafter<br />
- </indent>
- </Directory>
- </example>
+ <highlight language="config">
+# Trace the data read and written by mod_deflate
+# for a particular client (IP 192.168.1.31)
+# experiencing compression problems.
+# This filter will trace what goes into mod_deflate.
+ExtFilterDefine tracebefore \
+ cmd="/bin/tracefilter.pl /tmp/tracebefore" \
+ EnableEnv=trace_this_client
+
+# This filter will trace what goes after mod_deflate.
+# Note that without the ftype parameter, the default
+# filter type of AP_FTYPE_RESOURCE would cause the
+# filter to be placed *before* mod_deflate in the filter
+# chain. Giving it a numeric value slightly higher than
+# AP_FTYPE_CONTENT_SET will ensure that it is placed
+# after mod_deflate.
+ExtFilterDefine traceafter \
+ cmd="/bin/tracefilter.pl /tmp/traceafter" \
+ EnableEnv=trace_this_client ftype=21
+
+<Directory /usr/local/docs>
+ SetEnvIf Remote_Addr 192.168.1.31 trace_this_client
+ SetOutputFilter tracebefore;deflate;traceafter
+</Directory>
+ </highlight>
<example><title>Here is the filter which traces the data:</title>
- #!/usr/local/bin/perl -w<br />
- use strict;<br />
- <br />
- open(SAVE, ">$ARGV[0]")<br />
- <indent>
- or die "can't open $ARGV[0]: $?";<br />
- </indent>
- <br />
- while (<STDIN>) {<br />
- <indent>
- print SAVE $_;<br />
- print $_;<br />
- </indent>
- }<br />
- <br />
- close(SAVE);
+ <highlight language="perl">
+#!/usr/local/bin/perl -w
+use strict;
+
+open(SAVE, ">$ARGV[0]")
+ or die "can't open $ARGV[0]: $?";
+
+while (<STDIN>) {
+ print SAVE $_;
+ print $_;
+}
+
+close(SAVE);
+ </highlight>
</example>
</section>
</section> <!-- /Examples -->
filter is removed and the request continues without it.</dd>
</dl>
- <example><title>Example</title>
+ <highlight language="config">
ExtFilterOptions LogStderr
- </example>
+ </highlight>
<p>Messages written to the filter's standard error will be stored
in the Apache error log.</p>
<module>mod_rewrite</module>.</p>
<example><title>Example</title>
+ <highlight language="config">
MMapFile /usr/local/apache/htdocs/index.html
+ </highlight>
</example>
</usage>
</directivesynopsis>
<module>mod_rewrite</module>.</p>
<example><title>Example</title>
+ <highlight language="config">
CacheFile /usr/local/apache/htdocs/index.html
+ </highlight>
</example>
</usage>
</directivesynopsis>
<dl>
<dt>Server side Includes (SSI)</dt>
<dd>A simple case of replacing <directive>AddOutputFilterByType</directive>
- <example>
- FilterDeclare SSI<br/>
- FilterProvider SSI INCLUDES "%{CONTENT_TYPE} =~ m|^text/html|"<br/>
- FilterChain SSI
- </example>
+ <highlight language="config">
+FilterDeclare SSI
+FilterProvider SSI INCLUDES "%{CONTENT_TYPE} =~ m|^text/html|"
+FilterChain SSI
+ </highlight>
</dd>
<dt>Server side Includes (SSI)</dt>
<dd>The same as the above but dispatching on handler (classic
SSI behaviour; .shtml files get processed).
- <example>
- FilterProvider SSI INCLUDES "%{HANDLER} = 'server-parsed'"<br/>
- FilterChain SSI
- </example>
+ <highlight language="config">
+FilterProvider SSI INCLUDES "%{HANDLER} = 'server-parsed'"
+FilterChain SSI
+ </highlight>
</dd>
<dt>Emulating mod_gzip with mod_deflate</dt>
<dd>Insert INFLATE filter only if "gzip" is NOT in the
Accept-Encoding header. This filter runs with ftype CONTENT_SET.
- <example>
- FilterDeclare gzip CONTENT_SET<br/>
- FilterProvider gzip inflate "%{req:Accept-Encoding} !~ /gzip/"<br/>
- FilterChain gzip
- </example>
+ <highlight language="config">
+FilterDeclare gzip CONTENT_SET
+FilterProvider gzip inflate "%{req:Accept-Encoding} !~ /gzip/"
+FilterChain gzip
+ </highlight>
</dd>
<dt>Image Downsampling</dt>
<dd>Suppose we want to downsample all web images, and have filters
for GIF, JPEG and PNG.
- <example>
- FilterProvider unpack jpeg_unpack "%{CONTENT_TYPE} = 'image/jpeg'"<br/>
- FilterProvider unpack gif_unpack "%{CONTENT_TYPE} = 'image/gif'"<br/>
- FilterProvider unpack png_unpack "%{CONTENT_TYPE} = 'image/png'"<br/>
- <br />
- FilterProvider downsample downsample_filter "%{CONTENT_TYPE} = m|^image/(jpeg|gif|png)|"<br/>
- FilterProtocol downsample "change=yes"<br/>
- <br />
- FilterProvider repack jpeg_pack "%{CONTENT_TYPE} = 'image/jpeg'"<br/>
- FilterProvider repack gif_pack "%{CONTENT_TYPE} = 'image/gif'"<br/>
- FilterProvider repack png_pack "%{CONTENT_TYPE} = 'image/png'"<br/>
- <Location /image-filter><br/>
- <indent>
- FilterChain unpack downsample repack<br/>
- </indent>
- </Location>
- </example>
+ <highlight language="config">
+FilterProvider unpack jpeg_unpack "%{CONTENT_TYPE} = 'image/jpeg'"
+FilterProvider unpack gif_unpack "%{CONTENT_TYPE} = 'image/gif'"
+FilterProvider unpack png_unpack "%{CONTENT_TYPE} = 'image/png'"
+
+FilterProvider downsample downsample_filter "%{CONTENT_TYPE} = m|^image/(jpeg|gif|png)|"
+FilterProtocol downsample "change=yes"
+
+FilterProvider repack jpeg_pack "%{CONTENT_TYPE} = 'image/jpeg'"
+FilterProvider repack gif_pack "%{CONTENT_TYPE} = 'image/gif'"
+FilterProvider repack png_pack "%{CONTENT_TYPE} = 'image/png'"
+<Location /image-filter>
+ FilterChain unpack downsample repack
+</Location>
+ </highlight>
</dd>
</dl>
</section>
<code>text/html</code> or <code>text/plain</code> before it is sent
to the client.</p>
- <example>
+ <highlight language="config">
AddOutputFilterByType DEFLATE text/html text/plain
- </example>
+ </highlight>
<p>If you want the content to be processed by more than one filter, their
names have to be separated by semicolons. It's also possible to use one
<code>INCLUDES</code> filter and then by the <code>DEFLATE</code>
filter.</p>
- <example>
- <Location /cgi-bin/><br />
- <indent>
- Options Includes<br />
- AddOutputFilterByType INCLUDES;DEFLATE text/html<br />
- </indent>
- </Location>
- </example>
+ <highlight language="config">
+<Location /cgi-bin/>
+ Options Includes
+ AddOutputFilterByType INCLUDES;DEFLATE text/html
+</Location>
+ </highlight>
</usage>
href="../sections.html#mergin">configuration sections</a>. These
two directives have a different effect if reversed:</p>
- <example>
- RequestHeader append MirrorID "mirror 12"<br />
- RequestHeader unset MirrorID
- </example>
+ <highlight language="config">
+RequestHeader append MirrorID "mirror 12"
+RequestHeader unset MirrorID
+ </highlight>
<p>This way round, the <code>MirrorID</code> header is not set. If
reversed, the MirrorID header is set to "mirror 12".</p>
Copy all request headers that begin with "TS" to the
response headers:
- <example>
+ <highlight language="config">
Header echo ^TS
- </example>
+ </highlight>
</li>
<li>
the client to intuit load on the server or in isolating
bottlenecks between the client and the server.
- <example>
+ <highlight language="config">
Header set MyHeader "%D %t"
- </example>
+ </highlight>
<p>results in this header being added to the response:</p>
<li>
Say hello to Joe
- <example>
- Header set MyHeader "Hello Joe. It took %D microseconds \<br />
- for Apache to serve this request."
- </example>
+ <highlight language="config">
+Header set MyHeader "Hello Joe. It took %D microseconds for Apache to serve this request."
+ </highlight>
<p>results in this header being added to the response:</p>
stimulus. Note that this example requires the services of the
<module>mod_setenvif</module> module.
- <example>
- SetEnvIf MyRequestHeader myvalue HAVE_MyRequestHeader<br />
- Header set MyHeader "%D %t mytext" env=HAVE_MyRequestHeader
- </example>
+ <highlight language="config">
+SetEnvIf MyRequestHeader myvalue HAVE_MyRequestHeader
+Header set MyHeader "%D %t mytext" env=HAVE_MyRequestHeader
+ </highlight>
<p>If the header <code>MyRequestHeader: myvalue</code> is present on
the HTTP request, the response will contain the following header:</p>
description</a>) by replacing <var>https:</var> with
<var>http:</var> in the <var>Destination</var> header:
- <example>
+ <highlight language="config">
RequestHeader edit Destination ^https: http: early
- </example>
+ </highlight>
</li>
<li>
<code>NO_STORE</code> environment variables all existed for the
request):
- <example>
- Header merge Cache-Control no-cache env=CGI<br />
- Header merge Cache-Control no-cache env=NO_CACHE<br />
- Header merge Cache-Control no-store env=NO_STORE
- </example>
+ <highlight language="config">
+Header merge Cache-Control no-cache env=CGI
+Header merge Cache-Control no-cache env=NO_CACHE
+Header merge Cache-Control no-store env=NO_STORE
+ </highlight>
<p>then the response would contain the following header:</p>
</li>
<li>
Set a test cookie if and only if the client didn't send us a cookie
- <example>
+ <highlight language="config">
Header set Set-Cookie testcookie "expr=-z %{req:Cookie}"
- </example>
+ </highlight>
</li>
</ol>
</section>
<p>
Every 1 second, this module generates a single multicast UDP
packet, containing the number of busy and idle workers. The
- packet is a simple ASCII format, similiar to GET query parameters
+ packet is a simple ASCII format, similar to GET query parameters
in HTTP.
</p>
status information. This address will usually correspond to a configured
<directive module="mod_heartmonitor">HeartbeatListen</directive> on a
frontend proxy system.</p>
-<example>
+<highlight language="config">
HeartbeatAddress 239.0.0.1:27999
-</example>
+</highlight>
</usage>
</directivesynopsis>
module="mod_heartbeat">HeartbeatAddress</directive> on an origin server.
</p>
- <example>
+ <highlight language="config">
HeartbeatListen 239.0.0.1:27999
- </example>
+ </highlight>
<p> This module is inactive until this directive is used.</p>
</usage>
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