Apache HTTP Server Version 1.3

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Module mod_headers

This module provides for the customization of HTTP response headers.

Status: Extension
Source File: mod_headers.c
Module Identifier: headers_module
Compatibility: Available in Apache 1.2 and later.

Summary

Directives

• Header
• ErrorHeader

Header directive

This directive can replace, merge or remove HTTP response headers during 1xx and 2xx series replies. For 3xx, 4xx and 5xx use the ErrorHeader directive.

The action it performs is determined by the first argument. This can be one of the following values:

• set
  The response header is set, replacing any previous header with this name
• append
  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.
• add
  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.
• unset
  The response header of this name is removed, if it exists. If there are multiple headers of the same name, all will be removed.

Order of Processing

The Header directives are processed in the following order:

1. main server
2. virtual host
3. <Directory> sections and .htaccess
4. <Location>
5. <Files>

Header append Author "John P. Doe"
Header unset Author

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".

ErrorHeader directive

This directive can replace, merge or remove HTTP response headers on all replies including errors, redirects, and successful responses. To add headers only on sucessful (status 2xx) responses, use the Header directive.

This directive is identical to the Header directive in all other respects. Consult this directive for more information on the syntax.

Apache HTTP Server Version 1.3