Language Options

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.

Changelog for asp_tags

Version	Description
7.0.0	Removed from PHP.

precision
integer

The number of significant digits
displayed in floating point numbers. -1 means that an
enhanced algorithm for rounding such numbers will be
used.

serialize_precision integer

The number of significant digits stored
while serializing floating point numbers. -1 means that an
enhanced algorithm for rounding such numbers will be
used.

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.

See also References Explained.

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.

expose_php
boolean

Exposes to the world that PHP is installed on the
server, which includes the PHP version within the HTTP header
(e.g., X-Powered-By: PHP/5.3.7). Prior to PHP 5.5.0 the PHP logo
guids are also exposed, thus appending them to the URL of your PHP
script would display the appropriate logo (e.g., » https://www.php.net/?=PHPE9568F34-D428-11d2-A769-00AA001ACF42).
This also affected the output of phpinfo(), as
when disabled, the PHP logo and credits information would not be
displayed.

Note:

Since PHP 5.5.0 these guids and the php_logo_guid() function have been removed
from PHP and the guids are replaced with data URIs instead. Thus
accessing the PHP logo via appending the guid to the URL no longer
works. Similarly, turning expose_php
off will not affect seeing the PHP logo in phpinfo().

See also php_logo_guid() and phpcredits().

disable_functions string

This directive allows you to disable certain
functions for security
reasons. It takes on a comma-delimited list of function names.
disable_functions is not affected by Safe
Mode.

Only internal functions can be disabled using this directive.
User-defined
functions are unaffected.

This directive must be set in php.ini For example, you cannot set this in
httpd.conf.

disable_classes string

This directive allows you to disable
certain classes for security reasons. It takes on a comma-delimited list of
class names. disable_classes is not affected by Safe
Mode. This directive must be set
in php.ini For example, you cannot set
this in httpd.conf.

zend.assertions integer

When set to 1, assertion code
will be generated and executed (development mode). When set to
0, assertion code will be generated but it will be skipped
(not executed) at runtime. When set to -1, assertion code
will not be generated, making the assertions zero-cost (production
mode).

Note:

If a process is started in production mode,
zend.assertions cannot be changed at runtime, since the
code for assertions was not generated.

If a process is started in development mode,
zend.assertions cannot be set to -1 at
runtime.

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.

Warning

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

hard_timeout integer

zend.multibyte boolean

Enables parsing of source files in multibyte
encodings. Enabling zend.multibyte is required to use character
encodings like SJIS, BIG5, etc that contain special characters in
multibyte string data. ISO-8859-1 compatible encodings like UTF-8,
EUC, etc do not require this option.

Enabling zend.multibyte requires the mbstring
extension to be available.

zend.script_encoding string

This value will be used unless a declare(encoding=…) directive appears at the top
of the script. When ISO-8859-1 incompatible encoding is used, both
zend.multibyte and zend.script_encoding must be used.

Literal strings will be transliterated from
zend.script_enconding to mbstring.internal_encoding, as if
mb_convert_encoding() would have been
called.

zend.detect_unicode boolean

Check for BOM (Byte Order Mark) and see if the file
contains valid multibyte characters. This detection is performed
before processing of __halt_compiler(). Available only in Zend
Multibyte mode.

zend.signal_check boolean

To check for replaced signal handlers on
shutdown.

exit_on_timeout boolean

This is an Apache1 mod_php-only directive that
forces an Apache child to exit if a PHP execution timeout occurred.
Such a timeout causes an internal longjmp() call in Apache1 which
can leave some extensions in an inconsistent state. By terminating
the process any outstanding locks or memory will be cleaned up.

Resource Limits

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.

See also: max_execution_time.

Performance Tuning

Note:

Using open_basedir will disable the realpath cache.

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

Here’s a short explanation of the configuration
directives.

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, REQUEST, 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, REQUEST, 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. 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 byte 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.

Changelog for
post_max_size

Version	Description
5.3.4	post_max_size = 0 will not disable the limit when the content type is application/x-www-form-urlencoded or is not registered with PHP.
5.3.2 , 5.2.12	Allow unlimited post size by setting post_max_size to 0.

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

By default, PHP will output a media type using the
Content-Type header. To disable this, simply set it to be
empty.

PHP’s built-in default media type is set to
text/html.

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

Warning

This feature was DEPRECATED in PHP 5.6.0, and REMOVED as of PHP 7.0.0.

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”.

See also: magic_quotes_gpc, magic_quotes_runtime, and magic_quotes_sybase.

Paths and Directories

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.

Note:

Using open_basedir will set realpath_cache_size to 0 and thus disable the realpath cache.

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_ini.cache_ttl integer

user_ini.filename string

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.discard_path boolean

If this is enabled, the PHP CGI binary can safely
be placed outside of the web tree and people will not be able to
circumvent .htaccess security.

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.nph
boolean

If cgi.nph is enabled it will force cgi to always
sent Status: 200 with every request.

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.