Description of core php.ini directives

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_PERDIR	PHP_INI_ALL in PHP 4.0.0. PHP_INI_PERDIR in PHP >= 4.0.1.
asp_tags	"0"	PHP_INI_PERDIR	PHP_INI_ALL in PHP 4.0.0.
precision	"14"	PHP_INI_ALL
serialize_precision	"17"	PHP_INI_ALL	Available since PHP 4.3.2. Until PHP 5.3.5, the default value was 100.
y2k_compliance	"1"	PHP_INI_ALL	Removed in PHP 5.4.0.
allow_call_time_pass_reference	"1"	PHP_INI_PERDIR	PHP_INI_ALL in PHP 4.0.0. Removed in PHP 5.4.0.
disable_functions	""	PHP_INI_SYSTEM only	Available since PHP 4.0.1.
disable_classes	""	`php.ini` only	Available since PHP 4.3.2.
exit_on_timeout	""	PHP_INI_ALL	Available since PHP 5.3.0.
expose_php	"1"	`php.ini` only
zend.multibyte	"0"	PHP_INI_ALL	Available since PHP 5.4.0
zend.script_encoding	NULL	PHP_INI_ALL	Available since PHP 5.4.0
zend.detect-unicode	NULL	PHP_INI_ALL	Available since PHP 5.4.0
zend.signal_check	"0"	PHP_INI_SYSTEM	Available since PHP 5.4.0
zend.ze1_compatibility_mode	"0"	PHP_INI_ALL	Available since PHP 5.0.0. Removed in PHP 5.3.0
detect_unicode	"1"	PHP_INI_ALL	Available since PHP 5.1.0. Renamed to zend.detect-unicode from PHP 5.4.0.

Here's a short explanation of the configuration directives.

short_open_tag boolean

Tells PHP 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 affected the shorthand <?= before PHP 5.4.0, which is identical to <? echo. Use of this shortcut required short_open_tag to be on. Since PHP 5.4.0, <?= is always available.

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.

serialize_precision integer

The number of significant digits stored while serializing 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. 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 reasons. A function can modify its arguments in an undocumented way if it didn't declare that the argument shall be passed by reference. To prevent side-effects it's better to specify which arguments are passed by reference in the function declaration only.

Changelog for *allow_call_time_pass_reference*
Version	Description
5.4.0	Removed from PHP.
5.3.0	Emits an `E_DEPRECATED` level error.
5.0.0	Deprecated, and generates an `E_COMPILE_WARNING` level error.

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 compile-time flag was also required to define the functions memory_get_usage() and memory_get_peak_usage() prior to 5.2.1.

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

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.

The size represents the total number of bytes in the path strings stored, plus the size of the data associated with the cache entry. This means that in order to store longer paths in the cache, the cache size must be larger. This value does not directly control the number of distinct paths that can be cached.

The size required for the cache entry data is system dependent.

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_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. Removed in PHP 5.4.0.
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. Deprecated in PHP 5.3.0. Removed in PHP 5.4.0.
enable_post_data_reading	"1"	PHP_INI_PERDIR	Available since PHP 5.4.0
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	Removed in PHP 5.0.0.
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	"UTF-8"	PHP_INI_ALL	Defaults to "UTF-8" since PHP >= 5.6.0; empty for PHP < 5.6.0.
always_populate_raw_post_data	"0"	PHP_INI_PERDIR	PHP_INI_ALL in PHP <= 4.2.3. Available since PHP 4.1.0.

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, 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 equivalent 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.

Note that the default distribution php.ini files does not contain the 'C' for cookies, due to security concerns.

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 as of PHP 5.3.0 and REMOVED as of PHP 5.4.0.

register_argc_argv boolean

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

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.

Warning

This feature has been DEPRECATED as of PHP 5.3.0 and REMOVED as of PHP 5.4.0.

enable_post_data_reading boolean

Disabling this option causes $_POST and $_FILES not to be populated. The only way to read postdata will then be through the php://input stream wrapper. This can be useful to proxy requests or to process the POST data in a memory efficient fashion.

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 was removed in PHP 5.0.0. 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

In PHP 5.6 onwards, "UTF-8" is the default value and its value is used as the default character encoding for htmlentities(), html_entity_decode() and htmlspecialchars() if the encoding parameter is omitted. The value of default_charset will also be used to set the default character set for iconv functions if the iconv.input_encoding, iconv.output_encoding and iconv.internal_encoding configuration options are unset, and for mbstring functions if the mbstring.http_input mbstring.http_output mbstring.internal_encoding configuration option is unset.

All versions of PHP will use this value as the charset within the default Content-Type header sent by PHP if the header isn't overridden by a call to header().

Setting default_charset to an empty value is not recommended.

input_encoding string

Available from PHP 5.6.0. This setting is used for multibyte modules such as mbstring and iconv. Default is empty.

output_encoding string

Available from PHP 5.6.0. This setting is used for multibyte modules such as mbstring and iconv. Default is empty.

internal_encoding string

Available from PHP 5.6.0. This setting is used for multibyte modules such as mbstring and iconv. Default is empty. If empty, default_charset is used.

always_populate_raw_post_data mixed

If set to TRUE, PHP will always populate the $HTTP_RAW_POST_DATA containing the raw POST data. Otherwise, the variable is populated only when the MIME type of the data is unrecognised.

The preferred method for accessing raw POST data is php://input, and $HTTP_RAW_POST_DATA is deprecated in PHP 5.6.0 onwards. Setting always_populate_raw_post_data to -1 will opt into the new behaviour that will be implemented in a future version of PHP, in which $HTTP_RAW_POST_DATA is never defined.

Regardless of the setting, $HTTP_RAW_POST_DATA is not available with enctype="multipart/form-data".

Paths and Directories

**Paths and Directories Configuration Options**
Name	Default	Changeable	Changelog
include_path	".;/path/to/php/pear"	PHP_INI_ALL
open_basedir	NULL	PHP_INI_ALL	PHP_INI_SYSTEM in PHP < 5.3.0
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
zend_extension	NULL	`php.ini` only
zend_extension_debug	NULL	`php.ini` only	Available before PHP 5.3.0.
zend_extension_debug_ts	NULL	`php.ini` only	Available before PHP 5.3.0.
zend_extension_ts	NULL	`php.ini` only	Available before PHP 5.3.0.
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.
cgi.rfc2616_headers	"0"	PHP_INI_ALL	Available since PHP 4.3.0.
fastcgi.impersonate	"0"	PHP_INI_SYSTEM	Available since PHP 4.3.0. PHP_INI_ALL prior to PHP 5.2.1.
fastcgi.logging	"1"	PHP_INI_SYSTEM	Available since PHP 4.3.0. PHP_INI_ALL prior to PHP 5.2.1.

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.

PHP considers each entry in the include path separately when looking for files to include. It will check the first path, and if it doesn't find it, check the next path, until it either locates the included file or returns with a warning or an error. You may modify or set your include path at runtime using set_include_path().

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. However, it is more efficient to explicitly use include './file' than having PHP always check the current directory for every include.

Note:
ENV variables are also accessible in .ini files. As such it is possible to reference the home directory using ${LOGIN} and ${USER}.

Environment variables may vary between Server APIs as those environments may be different.

Example #3 Unix include_path using ${USER} env variable

include_path = ".:${USER}/pear/php"

open_basedir string

Limit the files that can be accessed by PHP to the specified directory-tree, including the file itself. This directive is NOT affected by whether Safe Mode is turned On or Off.

When a script tries to access the filesystem, for example using include, or fopen(), the location of the file is checked. When the file is outside the specified directory-tree, PHP will refuse to access it. All symbolic links are resolved, so it's not possible to avoid this restriction with a symlink. If the file doesn't exist then the symlink couldn't be resolved and the filename is compared to (a resolved) open_basedir .

open_basedir can affect more than just filesystem functions; for example if MySQL is configured to use mysqlnd drivers, LOAD DATA INFILE will be affected by open_basedir . Much of the extended functionality of PHP uses open_basedir in this way.

The special value . indicates that the working directory of the script will be used as the base-directory. This is, however, a little dangerous as the working directory of the script can easily be changed with chdir().

In httpd.conf, open_basedir can be turned off (e.g. for some virtual hosts) the same way as any other configuration directive with "php_admin_value open_basedir none".

Under Windows, separate the directories with a semicolon. On all other systems, separate the directories with a colon. As an Apache module, open_basedir paths from parent directories are now automatically inherited.

The restriction specified with open_basedir is a directory name since PHP 5.2.16 and 5.3.4. Previous versions used it as a prefix. This means that "open_basedir = /dir/incl" also allowed access to "/dir/include" and "/dir/incls" if they exist. When you want to restrict access to only the specified directory, end with a slash. For example: open_basedir = /dir/incl/

The default is to allow all files to be opened.

Note:
As of PHP 5.3.0 open_basedir can be tightened at run-time. This means that if open_basedir is set to /www/ in php.ini a script can tighten the configuration to /www/tmp/ at run-time with ini_set(). When listing several directories, you can use the PATH_SEPARATOR constant as a separator regardless of the operating system.

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.

zend_extension string

Name of dynamically loadable Zend extension (for example APD) to load when PHP starts up.

zend_extension_debug string

Variant of zend_extension for extensions compiled with debug info prior to PHP 5.3.0.

zend_extension_debug_ts string

Variant of zend_extension for extensions compiled with debug info and thread safety prior to PHP 5.3.0.

zend_extension_ts string

Variant of zend_extension for extensions compiled with thread safety prior to PHP 5.3.0.

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 its paths to conform to the spec. A setting of zero causes PHP to behave as before. It is turned on by default. 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: When using IIS this option must be turned off. For OmniHTTPD or Xitami the same applies.

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.

cgi.rfc2616_headers int

Tells PHP what type of headers to use when sending HTTP response code. If it's set to 0, PHP sends a » RFC 3875 "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.

If this option is enabled, and you are running PHP in a CGI environment (e.g. PHP-FPM) you should not use standard RFC 2616 style HTTP status response headers, you should instead use their RFC 3875 equivalent e.g. instead of header("HTTP/1.0 404 Not found"); you should use header("Status: 404 Not Found");

Leave it set to 0 unless you know what you're doing.

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.

fastcgi.logging boolean

Turns on SAPI logging when using FastCGI. Default is to enable logging.

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
max_input_nesting_level	64	PHP_INI_PERDIR	Available since PHP 5.3.9.
max_input_vars	1000	PHP_INI_PERDIR	Available since PHP 5.3.9.
upload_max_filesize	"2M"	PHP_INI_PERDIR	PHP_INI_ALL in PHP <= 4.2.3.
max_file_uploads	20	PHP_INI_SYSTEM	Available since PHP 5.2.12.

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.

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.

If the directory specified here is not writable, PHP falls back to the system default temporary directory. If open_basedir is on, then the system default directory must be allowed for an upload to succeed.

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.

max_file_uploads integer

The maximum number of files allowed to be uploaded simultaneously. Starting with PHP 5.3.4, upload fields left blank on submission do not count towards this limit.

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.

Windows Specific

**Windows Specific Configuration Options**
Name	Default	Changeable	Changelog
windows_show_crt_warning	"0"	PHP_INI_ALL	Available since PHP 5.4.0.

Here's a short explanation of the configuration directives.

windows_show_crt_warning boolean: This directive shows the Windows CRT warnings when enabled. These warnings were displayed by default until PHP 5.4.0.