php-doc-en/reference/session/ini.xml
Damien Seguy 745203632e add literal
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2009-06-29 16:35:13 +00:00

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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.59 $ -->
<section xml:id="session.configuration" xmlns="http://docbook.org/ns/docbook">
&reftitle.runtime;
&extension.runtime;
<para>
<table>
<title>Session configuration options</title>
<tgroup cols="4">
<thead>
<row>
<entry>Name</entry>
<entry>Default</entry>
<entry>Changeable</entry>
<entry>Changelog</entry>
</row>
</thead>
<tbody>
<row>
<entry><link linkend="ini.session.save-path">session.save_path</link></entry>
<entry>""</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.name">session.name</link></entry>
<entry>"PHPSESSID"</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.save-handler">session.save_handler</link></entry>
<entry>"files"</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.auto-start">session.auto_start</link></entry>
<entry>"0"</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.gc-probability">session.gc_probability</link></entry>
<entry>"1"</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.gc-divisor">session.gc_divisor</link></entry>
<entry>"100"</entry>
<entry>PHP_INI_ALL</entry>
<entry>Available since PHP 4.3.2.</entry>
</row>
<row>
<entry><link linkend="ini.session.gc-maxlifetime">session.gc_maxlifetime</link></entry>
<entry>"1440"</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.serialize-handler">session.serialize_handler</link></entry>
<entry>"php"</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.cookie-lifetime">session.cookie_lifetime</link></entry>
<entry>"0"</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.cookie-path">session.cookie_path</link></entry>
<entry>"/"</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.cookie-domain">session.cookie_domain</link></entry>
<entry>""</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.cookie-secure">session.cookie_secure</link></entry>
<entry>""</entry>
<entry>PHP_INI_ALL</entry>
<entry>Available since PHP 4.0.4.</entry>
</row>
<row>
<entry><link linkend="ini.session.cookie-httponly">session.cookie_httponly</link></entry>
<entry>""</entry>
<entry>PHP_INI_ALL</entry>
<entry>Available since PHP 5.2.0.</entry>
</row>
<row>
<entry><link linkend="ini.session.use-cookies">session.use_cookies</link></entry>
<entry>"1"</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.use-only-cookies">session.use_only_cookies</link></entry>
<entry>"1"</entry>
<entry>PHP_INI_ALL</entry>
<entry>Available since PHP 4.3.0.</entry>
</row>
<row>
<entry><link linkend="ini.session.referer-check">session.referer_check</link></entry>
<entry>""</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.entropy-file">session.entropy_file</link></entry>
<entry>""</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.entropy-length">session.entropy_length</link></entry>
<entry>"0"</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.cache-limiter">session.cache_limiter</link></entry>
<entry>"nocache"</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.cache-expire">session.cache_expire</link></entry>
<entry>"180"</entry>
<entry>PHP_INI_ALL</entry>
<entry></entry>
</row>
<row>
<entry><link linkend="ini.session.use-trans-sid">session.use_trans_sid</link></entry>
<entry>"0"</entry>
<entry>PHP_INI_ALL</entry>
<entry>PHP_INI_ALL in PHP &lt;= 4.2.3. PHP_INI_PERDIR in PHP &lt; 5. Available since PHP 4.0.3.</entry>
</row>
<row>
<entry><link linkend="ini.session.bug-compat-42">session.bug_compat_42</link></entry>
<entry>"1"</entry>
<entry>PHP_INI_ALL</entry>
<entry>Available since PHP 4.3.0. Removed in PHP 6.0.0.</entry>
</row>
<row>
<entry><link linkend="ini.session.bug-compat-warn">session.bug_compat_warn</link></entry>
<entry>"1"</entry>
<entry>PHP_INI_ALL</entry>
<entry>Available since PHP 4.3.0. Removed in PHP 6.0.0.</entry>
</row>
<row>
<entry><link linkend="ini.session.hash-function">session.hash_function</link></entry>
<entry>"0"</entry>
<entry>PHP_INI_ALL</entry>
<entry>Available since PHP 5.0.0.</entry>
</row>
<row>
<entry><link linkend="ini.session.hash-bits-per-character">session.hash_bits_per_character</link></entry>
<entry>"4"</entry>
<entry>PHP_INI_ALL</entry>
<entry>Available since PHP 5.0.0.</entry>
</row>
<row>
<entry><link linkend="ini.url-rewriter.tags">url_rewriter.tags</link></entry>
<entry>"a=href,area=href,frame=src,form=,fieldset="</entry>
<entry>PHP_INI_ALL</entry>
<entry>Available since PHP 4.0.4.</entry>
</row>
</tbody>
</tgroup>
</table>
&ini.php.constants;
</para>
<para>
The session management system supports a number of configuration
options which you can place in your &php.ini; file. We will give a
short overview.
<variablelist>
<varlistentry xml:id="ini.session.save-handler">
<term>
<parameter>session.save_handler</parameter>
<type>string</type>
</term>
<listitem>
<simpara>
<literal>session.save_handler</literal> defines the name of the
handler which is used for storing and retrieving data
associated with a session. Defaults to
<literal>files</literal>. Note that individual extensions may register
their own <literal>save_handler</literal>s; registered handlers can be
obtained on a per-installation basis by referring to
<function>phpinfo</function>. See also
<function>session_set_save_handler</function>.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.save-path">
<term>
<parameter>session.save_path</parameter>
<type>string</type>
</term>
<listitem>
<simpara>
<literal>session.save_path</literal> defines the argument which
is passed to the save handler. If you choose the default files
handler, this is the path where the files are created. See also
<function>session_save_path</function>.
</simpara>
<para>
There is an optional N argument to this directive that determines
the number of directory levels your session files will be spread
around in. For example, setting to <literal>'5;/tmp'</literal>
may end up creating a session file and location like
<literal>/tmp/4/b/1/e/3/sess_4b1e384ad74619bd212e236e52a5a174If
</literal>. In order to use N you must create all of these
directories before use. A small shell script exists in
<filename>ext/session</filename> to do this, it's called
<filename>mod_files.sh</filename>, with a Windows version called
<filename>mod_files.bat</filename>. Also note that if N is
used and greater than 0 then automatic garbage collection will
not be performed, see a copy of &php.ini; for further
information. Also, if you use N, be sure to surround
<literal>session.save_path</literal> in
"quotes" because the separator (<literal>;</literal>) is
also used for comments in &php.ini;.
</para>
<warning>
<para>
If you leave this set to a world-readable directory, such as
<filename>/tmp</filename> (the default), other users on the
server may be able to hijack sessions by getting the list of
files in that directory.
</para>
</warning>
<note>
<simpara>
Prior to PHP 4.3.6, Windows users had to change this variable in order
to use PHP's session functions. A valid path must be specified, e.g.:
<filename>c:/temp</filename>.
</simpara>
</note>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.name">
<term>
<parameter>session.name</parameter>
<type>string</type>
</term>
<listitem>
<simpara>
<literal>session.name</literal> specifies the name of the
session which is used as cookie name. It should only contain
alphanumeric characters. Defaults to <literal>PHPSESSID</literal>.
See also <function>session_name</function>.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.auto-start">
<term>
<parameter>session.auto_start</parameter>
<type>boolean</type>
</term>
<listitem>
<simpara>
<literal>session.auto_start</literal> specifies whether the
session module starts a session automatically on request
startup. Defaults to <literal>0</literal> (disabled).
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.serialize-handler">
<term>
<parameter>session.serialize_handler</parameter>
<type>string</type>
</term>
<listitem>
<simpara>
<literal>session.serialize_handler</literal> defines the name
of the handler which is used to serialize/deserialize
data. Currently, a PHP internal format (name <literal>php</literal> or
<literal>php_binary</literal>) and WDDX are supported (name
<literal>wddx</literal>). WDDX is only available, if PHP is
compiled with <link linkend="ref.wddx">WDDX
support</link>. Defaults to <literal>php</literal>.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.gc-probability">
<term>
<parameter>session.gc_probability</parameter>
<type>integer</type>
</term>
<listitem>
<simpara>
<literal>session.gc_probability</literal> in conjunction with
<literal>session.gc_divisor</literal> is used to manage probability
that the gc (garbage collection) routine is started.
Defaults to <literal>1</literal>. See <link
linkend="ini.session.gc-divisor">session.gc_divisor</link> for details.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.gc-divisor">
<term>
<parameter>session.gc_divisor</parameter>
<type>integer</type>
</term>
<listitem>
<simpara>
<literal>session.gc_divisor</literal> coupled with
<literal>session.gc_probability</literal> defines the probability
that the gc (garbage collection) process is started on every session
initialization.
The probability is calculated by using gc_probability/gc_divisor,
e.g. 1/100 means there is a 1% chance that the GC process starts
on each request.
<literal>session.gc_divisor</literal> defaults to <literal>100</literal>.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.gc-maxlifetime">
<term>
<parameter>session.gc_maxlifetime</parameter>
<type>integer</type>
</term>
<listitem>
<simpara>
<literal>session.gc_maxlifetime</literal> specifies the number
of seconds after which data will be seen as 'garbage' and
cleaned up. Garbage collection occurs during session start.
</simpara>
<note>
<para>
If different scripts have different values of
<literal>session.gc_maxlifetime</literal> but share the same place for
storing the session data then the script with the minimum value will be
cleaning the data. In this case, use this directive together with <link
linkend="ini.session.save-path">session.save_path</link>.
</para>
</note>
<note>
<simpara>If you are using the default file-based session handler, your
filesystem must keep track of access times (atime). Windows FAT does
not so you will have to come up with another way to handle garbage
collecting your session if you are stuck with a FAT filesystem or any
other filesystem where atime tracking is not available.
Since PHP 4.2.3 it has used mtime (modified date) instead of atime. So, you
won't have problems with filesystems where atime tracking is not available.
</simpara>
</note>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.referer-check">
<term>
<parameter>session.referer_check</parameter>
<type>string</type>
</term>
<listitem>
<simpara>
<literal>session.referer_check</literal> contains the
substring you want to check each HTTP Referer for. If the
Referer was sent by the client and the substring was not
found, the embedded session id will be marked as invalid.
Defaults to the empty string.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.entropy-file">
<term>
<parameter>session.entropy_file</parameter>
<type>string</type>
</term>
<listitem>
<simpara>
<literal>session.entropy_file</literal> gives a path to an
external resource (file) which will be used as an additional
entropy source in the session id creation process. Examples are
<literal>/dev/random</literal> or <literal>/dev/urandom</literal>
which are available on many Unix systems.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.entropy-length">
<term>
<parameter>session.entropy_length</parameter>
<type>integer</type>
</term>
<listitem>
<simpara>
<literal>session.entropy_length</literal> specifies the number
of bytes which will be read from the file specified
above. Defaults to <literal>0</literal> (disabled).
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.use-cookies">
<term>
<parameter>session.use_cookies</parameter>
<type>boolean</type>
</term>
<listitem>
<simpara>
<literal>session.use_cookies</literal> specifies whether the
module will use cookies to store the session id on the client
side. Defaults to <literal>1</literal> (enabled).
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.use-only-cookies">
<term>
<parameter>session.use_only_cookies</parameter>
<type>boolean</type>
</term>
<listitem>
<simpara>
<literal>session.use_only_cookies</literal> specifies whether
the module will <emphasis role="strong">only</emphasis> use
cookies to store the session id on the client side.
Enabling this setting prevents attacks involved passing session
ids in URLs. This setting was added in PHP 4.3.0.
Defaults to <literal>1</literal> (enabled) since PHP 5.3.0.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.cookie-lifetime">
<term>
<parameter>session.cookie_lifetime</parameter>
<type>integer</type>
</term>
<listitem>
<simpara>
<literal>session.cookie_lifetime</literal> specifies the lifetime of
the cookie in seconds which is sent to the browser. The value 0
means "until the browser is closed." Defaults to
<literal>0</literal>. See also
<function>session_get_cookie_params</function> and
<function>session_set_cookie_params</function>.
</simpara>
<note>
<para>
The expiration timestamp is set relative to the server time, which is
not necessarily the same as the time in the client's browser.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.cookie-path">
<term>
<parameter>session.cookie_path</parameter>
<type>string</type>
</term>
<listitem>
<simpara>
<literal>session.cookie_path</literal> specifies path to set
in session_cookie. Defaults to <literal>/</literal>. See also
<function>session_get_cookie_params</function> and
<function>session_set_cookie_params</function>.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.cookie-domain">
<term>
<parameter>session.cookie_domain</parameter>
<type>string</type>
</term>
<listitem>
<simpara>
<literal>session.cookie_domain</literal> specifies the domain to
set in session_cookie. Default is none at all meaning the host name of
the server which generated the cookie according to cookies specification.
See also <function>session_get_cookie_params</function> and
<function>session_set_cookie_params</function>.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.cookie-secure">
<term>
<parameter>session.cookie_secure</parameter>
<type>boolean</type>
</term>
<listitem>
<simpara>
<literal>session.cookie_secure</literal> specifies whether
cookies should only be sent over secure connections. Defaults to
<literal>off</literal>.
This setting was added in PHP 4.0.4. See also
<function>session_get_cookie_params</function> and
<function>session_set_cookie_params</function>.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.cookie-httponly">
<term>
<parameter>session.cookie_httponly</parameter>
<type>boolean</type>
</term>
<listitem>
<simpara>
Marks the cookie as accessible only through the HTTP protocol. This means
that the cookie won't be accessible by scripting languages, such as
JavaScript. This setting can effectively help to reduce identity theft
through XSS attacks (although it is not supported by all browsers).
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.cache-limiter">
<term>
<parameter>session.cache_limiter</parameter>
<type>string</type>
</term>
<listitem>
<simpara>
<literal>session.cache_limiter</literal> specifies cache
control method to use for session pages.
Il may be one of the following values :
<literal>nocache</literal>, <literal>private</literal>,
<literal>private_no_expire</literal>,<literal>public</literal>).
Defaults to <literal>nocache</literal>. See also
<function>session_cache_limiter</function>.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.cache-expire">
<term>
<parameter>session.cache_expire</parameter>
<type>integer</type>
</term>
<listitem>
<simpara>
<literal>session.cache_expire</literal> specifies time-to-live
for cached session pages in minutes, this has no effect for
nocache limiter. Defaults to <literal>180</literal>. See also
<function>session_cache_expire</function>.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.use-trans-sid">
<term>
<parameter>session.use_trans_sid</parameter>
<type>boolean</type>
</term>
<listitem>
<simpara>
<literal>session.use_trans_sid</literal> whether transparent
sid support is enabled or not. Defaults to
<literal>0</literal> (disabled).
</simpara>
<note>
<simpara>
For PHP 4.1.2 or less, it is enabled by compiling with
<link linkend="configure.enable-trans-sid">
<literal>--enable-trans-sid</literal></link>.
From PHP 4.2.0, trans-sid feature is always compiled.
</simpara>
<simpara>
URL based session management has additional security risks
compared to cookie based session management. Users may send
a URL that contains an active session ID to their friends by
email or users may save a URL that contains a session ID to
their bookmarks and access your site with the same session ID
always, for example.
</simpara>
</note>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.bug-compat-42">
<term>
<parameter>session.bug_compat_42</parameter>
<type>boolean</type>
</term>
<listitem>
<simpara>
PHP versions 4.2.3 and lower have an undocumented feature/bug that
allows you to initialize a session variable in the global scope,
albeit <link linkend="ini.register-globals">register_globals</link>
is disabled. PHP 4.3.0 and later will warn you, if this feature is
used, and if <link linkend="ini.session.bug-compat-warn">
session.bug_compat_warn</link> is also enabled. This feature/bug can be
disabled by disabling this directive.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.bug-compat-warn">
<term>
<parameter>session.bug_compat_warn</parameter>
<type>boolean</type>
</term>
<listitem>
<simpara>
PHP versions 4.2.3 and lower have an undocumented feature/bug that
allows you to initialize a session variable in the global scope,
albeit <link linkend="ini.register-globals">register_globals</link>
is disabled. PHP 4.3.0 and later will warn you, if this feature is
used by enabling both
<link linkend="ini.session.bug-compat-42">session.bug_compat_42</link>
and <link linkend="ini.session.bug-compat-warn">
session.bug_compat_warn</link>.
</simpara>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.hash-function">
<term>
<parameter>session.hash_function</parameter>
<type>mixed</type>
</term>
<listitem>
<simpara>
<literal>session.hash_function</literal> allows you to specify the hash
algorithm used to generate the session IDs. '0' means MD5 (128 bits) and
'1' means SHA-1 (160 bits).
</simpara>
<para>
Since PHP 6.0.0 it is also possible to specify any of the algorithms
provided by the <link linkend="ref.hash">hash extension</link> (if it is
available), like <literal>sha512</literal> or
<literal>whirlpool</literal>. A complete list of supported algorithms can
be obtained with the <function>hash_algos</function> function.
</para>
<note>
<para>
This was introduced in PHP 5.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.session.hash-bits-per-character">
<term>
<parameter>session.hash_bits_per_character</parameter>
<type>integer</type>
</term>
<listitem>
<simpara>
<literal>session.hash_bits_per_character</literal> allows you to define
how many bits are stored in each character when converting the binary
hash data to something readable. The possible values are '4' (0-9, a-f),
'5' (0-9, a-v), and '6' (0-9, a-z, A-Z, "-", ",").
</simpara>
<note>
<para>
This was introduced in PHP 5.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry xml:id="ini.url-rewriter.tags">
<term>
<parameter>url_rewriter.tags</parameter>
<type>string</type>
</term>
<listitem>
<simpara>
<literal>url_rewriter.tags</literal> specifies which HTML tags
are rewritten to include session id if transparent sid support
is enabled. Defaults to
<literal>a=href,area=href,frame=src,input=src,form=fakeentry,fieldset=</literal>
</simpara>
<note>
<simpara>
If you want HTML/XHTML strict conformity, remove the <literal>form</literal> entry and
use the &lt;fieldset&gt; tags around your form fields.
</simpara>
</note>
</listitem>
</varlistentry>
</variablelist>
</para>
<para>
The <link
linkend="ini.track-vars"><literal>track_vars</literal></link> and
<link
linkend="ini.register-globals"><literal>register_globals</literal></link>
configuration settings influence how the session variables get
stored and restored.
</para>
<note>
<para>
As of PHP 4.0.3, <link
linkend="ini.track-vars"><literal>track_vars</literal></link> is
always turned on.
</para>
</note>
</section>
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