| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> |
| <HTML> |
| <HEAD> |
| <TITLE>Apache module mod_headers</TITLE> |
| </HEAD> |
| |
| <!-- Background white, links blue (unvisited), navy (visited), red (active) --> |
| <BODY |
| BGCOLOR="#FFFFFF" |
| TEXT="#000000" |
| LINK="#0000FF" |
| VLINK="#000080" |
| ALINK="#FF0000" |
| > |
| <!--#include virtual="header.html" --> |
| <H1 ALIGN="CENTER">Module mod_headers</H1> |
| |
| The optional headers module allows for the customization of HTTP |
| response headers. Headers can be merged, replaced or removed. The |
| directives described in this document are only available if Apache is |
| compiled with <STRONG>mod_headers.c</STRONG>. |
| |
| <HR> |
| |
| <H2>Directive</H2> |
| <UL> |
| <LI><A HREF="#header">Header</A> |
| </UL> |
| |
| <HR> |
| |
| <H2><A NAME="header">Header</A></H2> |
| <A |
| HREF="directive-dict.html#Syntax" |
| REL="Help" |
| ><STRONG>Syntax:</STRONG></A> Header [ set | append | add ] |
| <EM>header</EM> <EM>value</EM><BR> |
| <A |
| HREF="directive-dict.html#Syntax" |
| REL="Help" |
| ><STRONG>Syntax:</STRONG></A> Header unset <EM>header</EM><BR> |
| <A |
| HREF="directive-dict.html#Context" |
| REL="Help" |
| ><STRONG>Context:</STRONG></A> server config, virtual host, access.conf, |
| .htaccess<BR> |
| <A |
| HREF="directive-dict.html#Status" |
| REL="Help" |
| ><STRONG>Status:</STRONG></A> optional<BR> |
| <A |
| HREF="directive-dict.html#Module" |
| REL="Help" |
| ><STRONG>Module:</STRONG></A> mod_header<P> |
| |
| This directive can replace, merge or remove HTTP response headers. The |
| action it performs is determined by the first argument. This can be one |
| of the following values: |
| |
| <UL> |
| <LI><STRONG>set</STRONG><BR> |
| The response header is set, replacing any previous header with this name |
| |
| <LI><STRONG>append</STRONG><BR> |
| The response header is appended to any existing header of the same |
| name. When a new value is merged onto an existing header it is |
| separated from the existing header with a comma. This is the HTTP standard |
| way of giving a header multiple values. |
| |
| <LI><STRONG>add</STRONG><BR> |
| The response header is added to the existing set of headers, even if |
| this header already exists. This can result in two (or more) headers |
| having the same name. This can lead to unforeseen consequences, and in |
| general "append" should be used instead. |
| |
| <LI><STRONG>unset</STRONG><BR> |
| The response header of this name is removed, if it exists. If there are |
| multiple headers of the same name, all will be removed. |
| </UL> |
| |
| This argument is followed by a header name, which can include the |
| final colon, but it is not required. Case is ignored. For |
| add, append and set a value is given as the third argument. If this |
| value contains spaces, it should be surrounded by double quotes. |
| For unset, no value should be given. |
| |
| <H3>Order of Processing</H3> |
| |
| The Header directive can occur almost anywhere within the server |
| configuration. It is valid in the main server config and virtual host |
| sections, inside <Directory>, <Location> and <Files> |
| sections, and within .htaccess files. |
| <P> |
| The Header directives are processed in the following order: |
| <OL> |
| <LI>main server |
| <LI>virtual host |
| <LI><Directory> sections and .htaccess |
| <LI><Location> |
| <LI><Files> |
| </OL> |
| |
| Order is important. These two headers have a different effect if reversed: |
| <PRE> |
| Header append Author "John P. Doe" |
| Header unset Author |
| </PRE> |
| |
| This way round, the Author header is not set. If reversed, the Author |
| header is set to "John P. Doe". |
| <P> |
| |
| The Header directives are processed just before the response is sent |
| by its handler. These means that some headers that are added just |
| before the response is sent cannot be unset or overridden. This |
| includes headers such as "Date" and "Server". |
| <P> |
| |
| <!--#include virtual="footer.html" --> |
| </BODY> |
| </HTML> |
