=encoding utf-8

=head1 NAME

ngx_http_sub_module - Module ngx_http_sub_module




=head1



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





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




=head1 Example Configuration




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






=head1 Directives

=head2 sub_filter


B<syntax:> sub_filter I<I<C<string>> I<C<replacement>>>



B<context:> I<http>


B<context:> I<server>


B<context:> I<location>





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 C<sub_filter> directives
can be specified on one configuration level (1.9.4).







=head2 sub_filter_last_modified


B<syntax:> sub_filter_last_modified I<C<on> E<verbar> C<off>>


B<default:> I<off>


B<context:> I<http>


B<context:> I<server>


B<context:> I<location>



This directive appeared in version 1.5.1.





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





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







=head2 sub_filter_once


B<syntax:> sub_filter_once I<C<on> E<verbar> C<off>>


B<default:> I<on>


B<context:> I<http>


B<context:> I<server>


B<context:> I<location>





Indicates whether to look for each string to replace
once or repeatedly.







=head2 sub_filter_types


B<syntax:> sub_filter_types I<I<C<mime-type>> ...>


B<default:> I<textE<sol>html>


B<context:> I<http>


B<context:> I<server>


B<context:> I<location>





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