1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
|
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!--
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
This file is generated from xml source: DO NOT EDIT
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
-->
<title>mod_expires - Apache HTTP Server</title>
<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" />
<script src="../style/scripts/prettify.js" type="text/javascript">
</script>
<link href="../images/favicon.ico" rel="shortcut icon" /></head>
<body>
<div id="page-header">
<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
<p class="apache">Apache HTTP Server Version 2.5</p>
<img alt="" src="../images/feather.gif" /></div>
<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
<div id="path">
<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.5</a> > <a href="./">Modules</a></div>
<div id="page-content">
<div id="preamble"><h1>Apache Module mod_expires</h1>
<div class="toplang">
<p><span>Available Languages: </span><a href="../en/mod/mod_expires.html" title="English"> en </a> |
<a href="../fr/mod/mod_expires.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a> |
<a href="../ja/mod/mod_expires.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
<a href="../ko/mod/mod_expires.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
</div>
<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Generation of <code>Expires</code> and
<code>Cache-Control</code> HTTP headers according to user-specified
criteria</td></tr>
<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="module-dict.html#ModuleIdentifier">Module�Identifier:</a></th><td>expires_module</td></tr>
<tr><th><a href="module-dict.html#SourceFile">Source�File:</a></th><td>mod_expires.c</td></tr></table>
<h3>Summary</h3>
<p>This module controls the setting of the <code>Expires</code>
HTTP header and the <code>max-age</code> directive of the
<code>Cache-Control</code> HTTP header in server responses. The
expiration date can set to be relative to either the time the
source file was last modified, or to the time of the client
access.</p>
<p>These HTTP headers are an instruction to the client about the
document's validity and persistence. If cached, the document may
be fetched from the cache rather than from the source until this
time has passed. After that, the cache copy is considered
"expired" and invalid, and a new copy must be obtained from the
source.</p>
<p>To modify <code>Cache-Control</code> directives other than
<code>max-age</code> (see <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9">RFC
2616 section 14.9</a>), you can use the <code class="directive"><a href="../mod/mod_headers.html#header">Header</a></code> directive.</p>
<p> When the <code>Expires</code> header is already part of the response
generated by the server, for example when generated by a CGI script or
proxied from an origin server, this module does not change or add
an <code>Expires</code> or <code>Cache-Control</code> header.</p>
</div>
<div id="quickview"><h3 class="directives">Directives</h3>
<ul id="toc">
<li><img alt="" src="../images/down.gif" /> <a href="#expiresactive">ExpiresActive</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#expiresbytype">ExpiresByType</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#expiresdefault">ExpiresDefault</a></li>
</ul>
<h3>Topics</h3>
<ul id="topics">
<li><img alt="" src="../images/down.gif" /> <a href="#AltSyn">Alternate Interval Syntax</a></li>
</ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="AltSyn" id="AltSyn">Alternate Interval Syntax</a></h2>
<p>The <code class="directive"><a href="#expiresdefault">ExpiresDefault</a></code> and
<code class="directive"><a href="#expiresbytype">ExpiresByType</a></code> directives
can also be defined in a more readable syntax of the form:</p>
<pre class="prettyprint lang-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>] ..."
</pre>
<p>where <var>base</var> is one of:</p>
<ul>
<li><code>access</code></li>
<li><code>now</code> (equivalent to
'<code>access</code>')</li>
<li><code>modification</code></li>
</ul>
<p>The <code>plus</code> keyword is optional. <var>num</var>
should be an integer value [acceptable to <code>atoi()</code>],
and <var>type</var> is one of:</p>
<ul>
<li><code>years</code></li>
<li><code>months</code></li>
<li><code>weeks</code></li>
<li><code>days</code></li>
<li><code>hours</code></li>
<li><code>minutes</code></li>
<li><code>seconds</code></li>
</ul>
<p>For example, any of the following directives can be used to
make documents expire 1 month after being accessed, by
default:</p>
<pre class="prettyprint lang-config">
ExpiresDefault "access plus 1 month"
ExpiresDefault "access plus 4 weeks"
ExpiresDefault "access plus 30 days"
</pre>
<p>The expiry time can be fine-tuned by adding several
'<var>num</var> <var>type</var>' clauses:</p>
<pre class="prettyprint lang-config">
ExpiresByType text/html "access plus 1 month 15 days 2 hours"
ExpiresByType image/gif "modification plus 5 hours 3 minutes"
</pre>
<p>Note that if you use a modification date based setting, the
Expires header will <strong>not</strong> be added to content
that does not come from a file on disk. This is due to the fact
that there is no modification time for such content.</p>
</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="ExpiresActive" id="ExpiresActive">ExpiresActive</a> <a name="expiresactive" id="expiresactive">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables generation of <code>Expires</code>
headers</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ExpiresActive On|Off</code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ExpiresActive Off</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Indexes</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_expires</td></tr>
</table>
<p>This directive enables or disables the generation of the
<code>Expires</code> and <code>Cache-Control</code> headers for
the document realm in question. (That is, if found in an
<code>.htaccess</code> file, for instance, it applies only to
documents generated from that directory.) If set to
<code>Off</code>, the headers will not be generated for any
document in the realm (unless overridden at a lower level, such as
an <code>.htaccess</code> file overriding a server config
file). If set to <code>On</code>, the headers will be added to
served documents according to the criteria defined by the
<code class="directive"><a href="#expiresbytype">ExpiresByType</a></code> and
<code class="directive"><a href="#expiresdefault">ExpiresDefault</a></code>
directives (<em>q.v.</em>).</p>
<p>Note that this directive does not guarantee that an
<code>Expires</code> or <code>Cache-Control</code> header will be
generated. If the criteria aren't met, no header will be sent, and
the effect will be as though this directive wasn't even
specified.</p>
</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="ExpiresByType" id="ExpiresByType">ExpiresByType</a> <a name="expiresbytype" id="expiresbytype">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Value of the <code>Expires</code> header configured
by MIME type</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ExpiresByType <var>MIME-type</var>
<var><code>seconds</var></code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Indexes</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_expires</td></tr>
</table>
<p>This directive defines the value of the <code>Expires</code>
header and the <code>max-age</code> directive of the
<code>Cache-Control</code> header generated for documents of the
specified type (<em>e.g.</em>, <code>text/html</code>). The second
argument sets the number of seconds that will be added to a base
time to construct the expiration date. The <code>Cache-Control:
max-age</code> is calculated by subtracting the request time from
the expiration date and expressing the result in seconds.</p>
<p>The base time is either the last modification time of the
file, or the time of the client's access to the document. Which
should be used is specified by the
<code><var><code></var></code> field; <code>M</code>
means that the file's last modification time should be used as
the base time, and <code>A</code> means the client's access
time should be used.</p>
<p>The difference in effect is subtle. If <code>M</code> is used,
all current copies of the document in all caches will expire at
the same time, which can be good for something like a weekly
notice that's always found at the same URL. If <code>A</code> is
used, the date of expiration is different for each client; this
can be good for image files that don't change very often,
particularly for a set of related documents that all refer to
the same images (<em>i.e.</em>, the images will be accessed
repeatedly within a relatively short timespan).</p>
<div class="example"><h3>Example:</h3><pre class="prettyprint lang-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
</pre>
</div>
<p>Note that this directive only has effect if
<code>ExpiresActive On</code> has been specified. It overrides,
for the specified MIME type <em>only</em>, any expiration date
set by the <code class="directive"><a href="#expiresdefault">ExpiresDefault</a></code>
directive.</p>
<p>You can also specify the expiration time calculation using
an <a href="#AltSyn">alternate syntax</a>, described earlier in
this document.</p>
</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="ExpiresDefault" id="ExpiresDefault">ExpiresDefault</a> <a name="expiresdefault" id="expiresdefault">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Default algorithm for calculating expiration time</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ExpiresDefault <var><code>seconds</var></code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Indexes</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_expires</td></tr>
</table>
<p>This directive sets the default algorithm for calculating the
expiration time for all documents in the affected realm. It can be
overridden on a type-by-type basis by the <code class="directive"><a href="#expiresbytype">ExpiresByType</a></code> directive. See the
description of that directive for details about the syntax of the
argument, and the <a href="#AltSyn">alternate syntax</a>
description as well.</p>
</div>
</div>
<div class="bottomlang">
<p><span>Available Languages: </span><a href="../en/mod/mod_expires.html" title="English"> en </a> |
<a href="../fr/mod/mod_expires.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a> |
<a href="../ja/mod/mod_expires.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
<a href="../ko/mod/mod_expires.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed again by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div>
<script type="text/javascript"><!--//--><![CDATA[//><!--
var comments_shortname = 'httpd';
var comments_identifier = 'http://httpd.apache.org/docs/trunk/mod/mod_expires.html';
(function(w, d) {
if (w.location.hostname.toLowerCase() == "httpd.apache.org") {
d.write('<div id="comments_thread"><\/div>');
var s = d.createElement('script');
s.type = 'text/javascript';
s.async = true;
s.src = 'https://comments.apache.org/show_comments.lua?site=' + comments_shortname + '&page=' + comments_identifier;
(d.getElementsByTagName('head')[0] || d.getElementsByTagName('body')[0]).appendChild(s);
}
else {
d.write('<div id="comments_thread">Comments are disabled for this page at the moment.<\/div>');
}
})(window, document);
//--><!]]></script></div><div id="footer">
<p class="apache">Copyright 2013 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div><script type="text/javascript"><!--//--><![CDATA[//><!--
if (typeof(prettyPrint) !== 'undefined') {
prettyPrint();
}
//--><!]]></script>
</body></html>
|
