<?xml version="1.0"?>

<!--
  Copyright (C) Igor Sysoev
  Copyright (C) Nginx, Inc.
  -->

<!DOCTYPE module SYSTEM "../../../../dtd/module.dtd">

<module name="Module ngx_http_sub_module"
        link="/en/docs/http/ngx_http_sub_module.html"
        lang="en"
        rev="6">

<section id="summary">

<para>
The <literal>ngx_http_sub_module</literal> module is a filter
that modifies a response by replacing one specified string by another.
</para>

<para>
This module is not built by default, it should be enabled with the
<literal>--with-http_sub_module</literal>
configuration parameter.
</para>

</section>


<section id="example" name="Example Configuration">

<para>
<example>
location / {
    sub_filter '&lt;a href="http://127.0.0.1:8080/'  '&lt;a href="https://$host/';
    sub_filter '&lt;img src="http://127.0.0.1:8080/' '&lt;img src="https://$host/';
    sub_filter_once on;
}
</example>
</para>

</section>


<section id="directives" name="Directives">

<directive name="sub_filter">
<syntax><value>string</value> <value>replacement</value></syntax>
<default/>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Sets a string to replace and a replacement string.
The string to replace is matched ignoring the case.
The string to replace (1.9.4) and replacement string can contain variables.
Several <literal>sub_filter</literal> directives
can be specified on the same configuration level (1.9.4).
These directives are inherited from the previous configuration level
if and only if there are no <literal>sub_filter</literal> directives
defined on the current level.
</para>

</directive>


<directive name="sub_filter_last_modified">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>off</default>
<context>http</context>
<context>server</context>
<context>location</context>
<appeared-in>1.5.1</appeared-in>

<para>
Allows preserving the <header>Last-Modified</header> header field
from the original response during replacement
to facilitate response caching.
</para>

<para>
By default, the header field is removed as contents of the response
are modified during processing.
</para>

</directive>


<directive name="sub_filter_once">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>on</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Indicates whether to look for each string to replace
once or repeatedly.
</para>

</directive>


<directive name="sub_filter_types">
<syntax><value>mime-type</value> ...</syntax>
<default>text/html</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Enables string replacement in responses with the specified MIME types
in addition to “<literal>text/html</literal>”.
The special value “<literal>*</literal>” matches any MIME type (0.8.29).
</para>

</directive>

</section>

</module>