Know more about your php.ini

Description of core php.ini directives

This list includes the core php.ini directives you can set to
configure your PHP setup. Directives handled by extensions are listed
and detailed at the extension documentation pages respectively;
Information on the session directives for example can be found at the
sessions page.

Httpd Options

Httpd Options

Name	Default	Changeable	Changelog
async_send	"0"	PHP_INI_ALL

Language Options

Language and Misc Configuration Options

Name	Default	Changeable	Changelog
short_open_tag	"1"	PHP_INI_ALL	PHP_INI_ALL in PHP <= 4.0.0. PHP_INI_PERDIR in PHP < 5.3.0
asp_tags	"0"	PHP_INI_PERDIR	PHP_INI_ALL in PHP <= 4.0.0.
precision	"14"	PHP_INI_ALL
y2k_compliance	"1"	PHP_INI_ALL
allow_call_time_pass_reference	"1"	PHP_INI_PERDIR	PHP_INI_ALL in PHP <= 4.0.0.
expose_php	"1"	php.ini only
zend.ze1_compatibility_mode	"0"	PHP_INI_ALL	Available since PHP 5.0.0. Removed in PHP 5.3.0

Here's a short explanation of
the configuration directives.

short_open_tag

boolean

Tells whether the short form (<? ?>
)
of PHP's open tag should be allowed. If you want to use PHP in
combination with XML, you can disable this option in order to
use <?xml ?>
inline. Otherwise, you
can print it with PHP, for example: <?php echo '<?xml
version="1.0"'; ?>
. Also if disabled, you must use the
long form of the PHP open tag (<?php ?>
).

Note:

This directive also affects the shorthand <?=
,
which is identical to <? echo
. Use of this
shortcut requires short_open_tag

to be on.

asp_tags

boolean

Enables the use of ASP-like <% %> tags in addition to
the usual <?php ?> tags. This includes the
variable-value printing shorthand of <%= $value %>. For
more information, see Escaping from HTML.

precision

integer

The number of significant digits displayed in floating point numbers.

y2k_compliance

boolean

Enforce year 2000 compliance (will cause problems with non-compliant browsers)

allow_call_time_pass_reference

boolean

Whether to warn when arguments are passed by reference
at function call time. This method is deprecated and is likely to be
unsupported in future versions of PHP/Zend. The encouraged method of
specifying which arguments should be passed by reference is in the function
declaration. You're encouraged to try and turn this option Off and make
sure your scripts work properly with it in order to ensure they will work
with future versions of the language (you will receive a warning each time
you use this feature).

Passing arguments by reference at function call time was deprecated for
code cleanliness reason. Function can modify its argument in
undocumented way if it didn't declared that the argument is passed by
reference. To prevent side-effects it's better to specify which
arguments are passed by reference in function declaration only.

See also References Explained.

expose_php

boolean

Decides whether PHP may expose the fact that it is installed on the server
(e.g. by adding its signature to the Web server header). It is no security
threat in any way, but it makes it possible to determine whether you use PHP
on your server or not.

zend.ze1_compatibility_mode

boolean

Enable compatibility mode with Zend Engine 1 (PHP 4). It affects
the cloning, casting (objects with no properties cast to FALSE or 0), and comparing of objects.
In this mode, objects are passed by value instead of reference by
default.

See also the section titled
Migrating from PHP 4 to PHP 5.

Resource Limits

Resource Limits

Name	Default	Changeable	Changelog
memory_limit	"128M"	PHP_INI_ALL	"8M" before PHP 5.2.0, "16M" in PHP 5.2.0

Here's a short explanation of
the configuration directives.

memory_limit

integer

This sets the maximum amount of memory in bytes that a script
is allowed to allocate. This helps prevent poorly written
scripts for eating up all available memory on a server. Note that
to have no memory limit, set this directive to -1.

Prior to PHP 5.2.1, in order to use this directive it had to
be enabled at compile time by using
-enable-memory-limit in the
configure line. This was also required to define the functions
memory_get_usage() and
memory_get_peak_usage().

When an integer is used, the
value is measured in bytes. Shorthand notation, as described
in this FAQ, may also be used.

See also: max_execution_time.

Performance Tuning

Performance Tuning

Name	Default	Changeable	Changelog
realpath_cache_size	"16K"	PHP_INI_SYSTEM	Available since PHP 5.1.0.
realpath_cache_ttl	"120"	PHP_INI_SYSTEM	Available since PHP 5.1.0.

Here's a short explanation of
the configuration directives.

realpath_cache_size

integer

Determines the size of the realpath cache to be used by PHP. This
value should be increased on systems where PHP opens many files, to
reflect the quantity of the file operations performed.

realpath_cache_ttl

integer

Duration of time (in seconds) for which to cache realpath information
for a given file or directory. For systems with rarely changing files,
consider increasing the value.

Data Handling

Data Handling Configuration Options

Name	Default	Changeable	Changelog
track_vars	"On"	PHP_INI_??
arg_separator.output	"&"	PHP_INI_ALL	Available since PHP 4.0.5.
arg_separator.input	"&"	PHP_INI_PERDIR	Available since PHP 4.0.5.
variables_order	"EGPCS"	PHP_INI_PERDIR	PHP_INI_ALL in PHP <= 5.0.5.
request_order	""	PHP_INI_SYSTEM|PHP_INI_PERDIR	Available since PHP 5.3.0
auto_globals_jit	"1"	PHP_INI_PERDIR	Available since PHP 5.0.0.
register_globals	"0"	PHP_INI_PERDIR	PHP_INI_ALL in PHP <= 4.2.3.
register_argc_argv	"1"	PHP_INI_PERDIR	PHP_INI_ALL in PHP <= 4.2.3.
register_long_arrays	"1"	PHP_INI_PERDIR	Available since PHP 5.0.0.
post_max_size	"8M"	PHP_INI_PERDIR	PHP_INI_SYSTEM in PHP <= 4.2.3. Available since PHP 4.0.3.
gpc_order	"GPC"	PHP_INI_ALL
auto_prepend_file	NULL	PHP_INI_PERDIR	PHP_INI_ALL in PHP <= 4.2.3.
auto_append_file	NULL	PHP_INI_PERDIR	PHP_INI_ALL in PHP <= 4.2.3.
default_mimetype	"text/html"	PHP_INI_ALL
default_charset	""	PHP_INI_ALL
always_populate_raw_post_data	"0"	PHP_INI_PERDIR	PHP_INI_ALL in PHP <= 4.2.3. Available since PHP 4.1.0.
allow_webdav_methods	"0"	PHP_INI_PERDIR

Here's a short explanation of
the configuration directives.

track_vars

boolean

If enabled, then Environment, GET, POST, Cookie, and Server
variables can be found in the global associative arrays
$_ENV,
$_GET,
$_POST,
$_COOKIE, and
$_SERVER.

Note that as of PHP 4.0.3, track_vars
is always turned on.

arg_separator.output

string

The separator used in PHP generated URLs to separate arguments.

arg_separator.input

string

List of separator(s) used by PHP to parse input URLs into variables.

Note:

Every character in this directive is considered as separator!

variables_order

string

Sets the order of the EGPCS (Environment,
Get, Post,
Cookie, and Server) variable
parsing. For example, if variables_order
is set to "SP" then PHP will create the
superglobals $_SERVER and
$_POST, but not create
$_ENV, $_GET, and
$_COOKIE. Setting to "" means no
superglobals will be set.

If the deprecated
register_globals
directive is on (removed as of PHP 6.0.0), then variables_order also
configures the order the ENV,
GET, POST,
COOKIE and SERVER variables
are populated in global scope. So for example if variables_order
is set to "EGPCS", register_globals is enabled,
and both $_GET['action'] and
$_POST['action'] are set, then
$action will contain the value of
$_POST['action'] as P comes
after G in our example directive value.

Warning

In both the CGI and FastCGI SAPIs,
$_SERVER is
also populated by values from the environment; S
is always equivelant to ES regardless of the
placement of E elsewhere in this directive.

Note:

The content and order of
$_REQUEST is also
affected by this directive.

request_order

string

This directive describes the order in which PHP registers GET, POST
and Cookie variables into the _REQUEST array. Registration is done
from left to right, newer values override older values.

If this directive is not set, variables_order is used for
$_REQUEST contents.

auto_globals_jit

boolean

When enabled, the SERVER and ENV variables are created when they're
first used (Just In Time) instead of when the script starts. If these
variables are not used within a script, having this directive on will
result in a performance gain.

The PHP directives
register_globals,
register_long_arrays,
and register_argc_argv
must be disabled for this directive to have any affect. Since PHP
5.1.3 it is not necessary to have register_argc_argv disabled.

Warning

Usage of SERVER and ENV variables is checked during the compile time
so using them through e.g. variable variables will
not cause their initialization.

register_globals

boolean

Whether or not to register the EGPCS (Environment, GET,
POST, Cookie, Server) variables as global variables.

As of » PHP 4.2.0,
this directive defaults to off.

Please read the security chapter on
Using register_globals
for related information.

Please note that register_globals

cannot be set at runtime (ini_set()). Although, you can
use .htaccess if your host allows it as described
above. An example .htaccess entry:
php_flag register_globals off

.

Note:

register_globals
is affected
by the variables_order
directive.

Warning

This feature has been

DEPRECATED and REMOVED as of PHP 6.0.0.
Relying on this feature is highly discouraged.

register_argc_argv

boolean

Tells PHP whether to declare the argv & argc variables
(that would contain the GET information).



See also command line.
Also, this directive became available in PHP 4.0.0 and
was always "on" before that.

register_long_arrays

boolean

Tells PHP whether or not to register the deprecated long
$HTTP_*_VARS type
predefined
variables. When On (default), long predefined PHP
variables like $HTTP_GET_VARS will be defined.
If you're not using them, it's recommended to turn them off,
for performance reasons. Instead, use the superglobal arrays,
like $_GET.



This directive became available in PHP 5.0.0 and was dropped in PHP
6.0.0.

post_max_size

integer

Sets max size of post data allowed. This setting also affects
file upload. To upload large files, this value must be larger
than upload_max_filesize.


If memory limit is enabled by your configure script, memory_limit also affects
file uploading. Generally speaking,
memory_limit should be
larger than post_max_size

.


When an integer is used, the
value is measured in bytes. Shorthand notation, as described
in this FAQ, may also be used.



If the size of post data is greater than post_max_size, the
$_POST and $_FILES

superglobals
are empty. This can be tracked in various ways, e.g. by passing the
$_GET variable to the script processing the data,
i.e. <form action="edit.php?processed=1">,
and then checking if $_GET['processed'] is set.

Note:

PHP allows shortcuts for bit values, including K (kilo), M (mega)
and G (giga). PHP will do the conversions automatically if you
use any of these. Be careful not to exceed the 32 bit signed integer
limit (if you're using 32bit versions) as it will cause your script
to fail.

gpc_order

string

Set the order of GET/POST/COOKIE variable parsing. The
default setting of this directive is "GPC". Setting this to
"GP", for example, will cause PHP to completely ignore cookies
and to overwrite any GET method variables with POST-method
variables of the same name.

Note:

This option is not available in PHP 4.
Use variables_order
instead.

auto_prepend_file

string

Specifies the name of a file that is automatically parsed
before the main file. The file is included as if it was
called with the require() function, so
include_path is used.

The special value none
disables auto-prepending.

auto_append_file

string

Specifies the name of a file that is automatically parsed
after the main file. The file is included as if it was
called with the require() function, so
include_path is used.

The special value none
disables auto-appending.

Note:

If the script is terminated with exit(),
auto-append will not occur.

default_mimetype

string

default_charset

string

As of 4.0.0, PHP always outputs a character encoding by default in
the Content-type: header. To disable sending of the charset, simply
set it to be empty.

always_populate_raw_post_data

boolean

Always populate the $HTTP_RAW_POST_DATA containing
the raw POST data. Otherwise, the variable is populated only with
unrecognized MIME type of the data. However, the preferred method for
accessing the raw POST data is php://input.
$HTTP_RAW_POST_DATA is not available with
enctype="multipart/form-data".

allow_webdav_methods

boolean

Allow handling of WebDAV http requests within PHP scripts (eg.
PROPFIND, PROPPATCH, MOVE, COPY, etc.).
This directive does not exist as of PHP 4.3.2.
If you want to get the post data of those requests, you have to
set
always_populate_raw_post_data as well.

See also: magic_quotes_gpc,
magic_quotes_runtime,
and
magic_quotes_sybase.

Paths and Directories

Paths and Directories Configuration Options

Name	Default	Changeable	Changelog
include_path	".;/path/to/php/pear"	PHP_INI_ALL
doc_root	NULL	PHP_INI_SYSTEM
user_dir	NULL	PHP_INI_SYSTEM
extension_dir	"/path/to/php"	PHP_INI_SYSTEM
extension	NULL	php.ini only
cgi.check_shebang_line	"1"	PHP_INI_SYSTEM	Available since PHP 5.2.0.
cgi.fix_pathinfo	"1"	PHP_INI_SYSTEM	Available since PHP 4.3.0. PHP_INI_ALL prior to PHP 5.2.1.
cgi.force_redirect	"1"	PHP_INI_SYSTEM	Available since PHP 4.2.0. PHP_INI_ALL prior to PHP 5.2.1.
cgi.redirect_status_env	NULL	PHP_INI_SYSTEM	Available since PHP 4.2.0. PHP_INI_ALL prior to PHP 5.2.1.
fastcgi.impersonate	"0"	PHP_INI_SYSTEM	Available since PHP 4.3.0. PHP_INI_ALL prior to PHP 5.2.1.
cgi.rfc2616_headers	"0"	PHP_INI_ALL	Available since PHP 4.3.0.

Here's a short explanation of
the configuration directives.

include_path

string

Specifies a list of directories where the
require(), include(),
fopen(), file(),
readfile() and file_get_contents()

functions look for files. The format is like the system's
PATH environment variable: a list of directories
separated with a colon in Unix or semicolon in Windows.

Example #1 Unix include_path

include_path=".:/php/includes"

Example #2 Windows include_path

include_path=".;c:\php\includes"

Using a . in the include path allows for
relative includes as it means the current directory.

doc_root

string

PHP's "root directory" on the server. Only used if
non-empty. If PHP is configured with safe mode, no files outside
this directory are served.
If PHP was not compiled with FORCE_REDIRECT, you should
set doc_root if you are running PHP as a CGI under any web
server (other than IIS). The alternative is to use the


cgi.force_redirect configuration below.

user_dir

string

The base name of the directory used on a user's home directory for PHP
files, for example public_html
.

extension_dir

string

In what directory PHP should look for dynamically loadable
extensions. See also: enable_dl,
and dl().

extension

string

Which dynamically loadable extensions to load when PHP starts up.

cgi.check_shebang_line

boolean

Controls whether CGI PHP checks for line starting with #! (shebang)
at the top of the running script. This line might be needed if the
script support running both as stand-alone script and via PHP CGI.
PHP in CGI mode skips this line and ignores its content if this
directive is turned on.

cgi.fix_pathinfo

boolean

Provides real PATH_INFO/PATH_TRANSLATED
support for CGI. PHP's previous behaviour was to set
PATH_TRANSLATED to SCRIPT_FILENAME, and to not grok what PATH_INFO
is. For more information on PATH_INFO, see the cgi specs. Setting
this to 1 will cause PHP CGI to fix it's paths to conform to the
spec. A setting of zero causes PHP to behave as before. Default
is zero. You should fix your scripts to use SCRIPT_FILENAME rather
than PATH_TRANSLATED.

cgi.force_redirect

boolean

cgi.force_redirect is necessary to provide security running PHP as a
CGI under most web servers. Left undefined, PHP turns this on by
default. You can turn it off at your own risk.

Note:

Windows Users: You can safely turn this off for
IIS, in fact, you must.
To get OmniHTTPD or Xitami to work you must turn
it off.

cgi.redirect_status_env

string

If cgi.force_redirect is turned on, and you are not running under
Apache or Netscape (iPlanet) web servers, you may
need to set an environment variable name that PHP will look for to
know it is OK to continue execution.

Note:

Setting this variable may cause security issues,
know what you are doing first.

fastcgi.impersonate

string

FastCGI under IIS (on WINNT based OS) supports the ability to impersonate
security tokens of the calling client. This allows IIS to define the
security context that the request runs under. mod_fastcgi under Apache
does not currently support this feature (03/17/2002)
Set to 1 if running under IIS. Default is zero.

cgi.rfc2616_headers

int

Tells PHP what type of headers to use when sending HTTP response
code. If it's set 0, PHP sends a Status: header that is supported
by Apache and other web servers. When this option is set to 1, PHP
will send » RFC 2616 compliant
headers. Leave it set to 0 unless you know what you're doing.

File Uploads

File Uploads Configuration Options

Name	Default	Changeable	Changelog
file_uploads	"1"	PHP_INI_SYSTEM	PHP_INI_ALL in PHP <= 4.2.3. Available since PHP 4.0.3.
upload_tmp_dir	NULL	PHP_INI_SYSTEM
upload_max_filesize	"2M"	PHP_INI_PERDIR	PHP_INI_ALL in PHP <= 4.2.3.

Here's a short explanation of
the configuration directives.

file_uploads

boolean

Whether or not to allow HTTP
file uploads. See also the
upload_max_filesize,
upload_tmp_dir, and
post_max_size directives.

When an integer is used, the
value is measured in bytes. Shorthand notation, as described
in this FAQ, may also be used.

upload_tmp_dir

string

The temporary directory used for storing files when doing
file upload. Must be writable by whatever user PHP
is running as. If not specified PHP will use the system's default.

upload_max_filesize

integer

The maximum size of an uploaded file.

When an integer is used, the
value is measured in bytes. Shorthand notation, as described
in this FAQ, may also be used.

General SQL

General SQL Configuration Options

Name	Default	Changeable	Changelog
sql.safe_mode	"0"	PHP_INI_SYSTEM

Here's a short explanation of
the configuration directives.

sql.safe_mode

boolean

If turned on, database connect functions that specify default values
will use those values in place of supplied arguments. For default
values see connect function documentation for the relevant database.