<div class="directive-section"><h2><a name="Header" id="Header">Header</a> <a name="header" id="header">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configure HTTP response headers</td></tr>
-<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Header [<var>condition</var>] add|append|echo|edit|edit*|merge|set|unset|note
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Header [<var>condition</var>] add|append|echo|edit|edit*|merge|set|setifempty|unset|note
<var>header</var> [<var>[expr=]value]</var>] [<var>replacement</var>]
[early|env=[!]<var>variable</var>]|expr=<var>expression</var>]
</code></td></tr>
<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</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_headers</td></tr>
-<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>SetIfEmpty available in 2.4.7 and later</td></tr>
+<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>SetIfEmpty and note available in 2.4.7 and later</td></tr>
</table>
<p>This directive can replace, merge or remove HTTP response
headers. The header is modified just after the content handler
<dt><code>setifempty</code></dt>
<dd>The request header is set, but only if there is no previous header
- with this name. Available in 2.4.7 and later.</dd>
+ with this name.<br />
+ Available in 2.4.7 and later.</dd>
<dt><code>unset</code></dt>
<dd>The response header of this name is removed, if it exists.
<dd>The value of the named response <var>header</var> is copied into an
internal note whose name is given by <var>value</var>. This is useful
if a header sent by a CGI or proxied resource is configured to be unset
- but should also be logged.</dd>
+ but should also be logged.<br />
+ Available in 2.4.7 and later.</dd>
</dl>
designed to expose the values obtained by <code>getloadavg()</code>
and this represents the current load average, the 5 minute average, and
the 15 minute average. The value is preceded by <code>l=</code> with each
- average separated by <code>/</code>.
+ average separated by <code>/</code>.<br />
+ Available in 2.4.4 and later.
</td></tr>
<tr><td><code>%i</code></td>
<td>The current idle percentage of httpd (0 to 100) based on available
- processes and threads. The value is preceded by <code>i=</code>.
+ processes and threads. The value is preceded by <code>i=</code>.<br />
+ Available in 2.4.4 and later.
</td></tr>
<tr class="odd"><td><code>%b</code></td>
<td>The current busy percentage of httpd (0 to 100) based on available
- processes and threads. The value is preceded by <code>b=</code>.
+ processes and threads. The value is preceded by <code>b=</code>.<br />
+ Available in 2.4.4 and later.
</td></tr>
<tr><td><code>%{VARNAME}e</code></td>
<td>The contents of the <a href="../env.html">environment
<p>For <code>edit</code> there is both a <var>value</var> argument
which is a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>,
- and an additional <var>replacement</var> string. The replacement string
- may also contain format specifiers.</p>
+ and an additional <var>replacement</var> string. As of version 2.4.7
+ the replacement string may also contain format specifiers.</p>
<p>The <code class="directive">Header</code> directive may be followed by
an additional argument, which may be any of:</p>
<dt><code>set</code></dt>
<dd>The request header is set, replacing any previous header
with this name</dd>
-
+
<dt><code>setifempty</code></dt>
<dd>The request header is set, but only if there is no previous header
- with this name. Available in 2.4.7 and later.</dd>
+ with this name.<br />
+ Available in 2.4.7 and later.</dd>
<dt><code>unset</code></dt>
<dd>The request header of this name is removed, if it exists. If