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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.
Note:
The defaults listed here are used when php.ini is not loaded; the values for the production and development php.ini may vary.
Language Options
Here's a short explanation of
the configuration directives.
-
short_open_tag
bool
-
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 does not affect the shorthand
<?= , which is always available.
-
precision
int
-
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
int
-
The number of significant digits stored while serializing floating point numbers.
-1 means that an enhanced algorithm for rounding
such numbers will be used.
-
expose_php
bool
-
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).
-
disable_functions
string
-
This directive allows disables certain functions.
It takes on a comma-delimited list of function names.
As of PHP 8.0.0, disabling a function removes it definition
allowing userland to redefine it.
Prior to PHP 8.0.0, disabling a function just prevent invoking the function.
Only internal functions can
be disabled using this directive.
User-defined functions
are unaffected.
This directive must be set in php.ini.
It cannot be set in httpd.conf.
-
disable_classes
string
-
This directive allows disables certain classes.
It takes on a comma-delimited list of class names.
Disabling a class just prevent instantiating the class.
Only internal classes can be disabled using this directive.
User-defined classes are unaffected.
This directive must be set in php.ini.
It cannot be set in httpd.conf.
-
zend.assertions
int
-
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.exception_string_param_max_len
int
-
The maximum length of string function arguments in stringified stack traces.
Must range between
"0" and "1000000" .
-
hard_timeout
int
-
When the timeout set in max_execution_time
has been hit, the PHP runtime will tear down resources gracefully. If
something gets stuck while this happens, the hard timeout will tick
for the set amount of seconds. When the hard timeout is hit, PHP will
exit ungracefully. When set to 0, the hard timeout will never activate.
When PHP stops from a hard timeout, it will look something like this:
Fatal error: Maximum execution time of 30+2 seconds exceeded (terminated) in Unknown on line 0
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zend.exception_ignore_args
bool
-
Excludes arguments from stack traces generated from exceptions.
-
zend.multibyte
bool
-
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_encoding to
mbstring.internal_encoding, as if
mb_convert_encoding would have been called.
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zend.detect_unicode
bool
-
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.
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zend.signal_check
bool
-
To check for replaced signal handlers on shutdown.
-
exit_on_timeout
bool
-
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
Resource Limits
Name |
Default |
Changeable |
Changelog |
memory_limit |
"128M" |
INI_ALL |
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Here's a short explanation of
the configuration directives.
-
memory_limit
int
-
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 .
When an int is used, the
value is measured in bytes. Shorthand notation, as described
in this FAQ, may also be used.
See also: max_execution_time.
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 (E nvironment,
G et, P ost,
C ookie, and S erver) 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.
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
bool
-
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.
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_argc_argv
bool
-
Tells PHP whether to declare the argv & argc variables
(that would contain the GET information).
See also command line.
-
enable_post_data_reading
bool
-
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
int
-
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 int 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.
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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
-
"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
-
This setting is used for multibyte modules
such as mbstring and iconv. Default is empty.
-
output_encoding
string
-
This setting is used for multibyte modules
such as mbstring and iconv. Default is empty.
-
internal_encoding
string
-
This setting is used for multibyte modules
such as mbstring and iconv. Default is empty. If empty,
default_charset is used.
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 an
E_WARNING
or an E_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.
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, not a prefix.
The default is to allow all files to be opened.
Note:
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.
Caution
open_basedir is just an extra safety net, that is in no way
comprehensive, and can therefore not be relied upon when security is needed.
-
doc_root
string
-
PHP's "root directory" on the server. Only used if
non-empty.
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
int
-
-
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. It is recommended to specify an absolute path. 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
XDebug) to load when PHP starts up.
-
cgi.check_shebang_line
bool
-
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
bool
-
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
bool
-
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
bool
-
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
bool
-
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.
-
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
bool
-
Turns on SAPI logging when using FastCGI. Default is
to enable logging.
File Uploads
Here's a short explanation of
the configuration directives.
-
file_uploads
bool
-
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
int
-
The maximum size of an uploaded file.
post_max_size must be larger than this value.
When an int is used, the
value is measured in bytes. Shorthand notation, as described
in this FAQ, may also be used.
-
max_file_uploads
int
-
The maximum number of files allowed to be uploaded simultaneously.
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" |
INI_SYSTEM |
Removed as of PHP 7.2.0 |
Here's a short explanation of
the configuration directives.
-
sql.safe_mode
bool
-
If turned on, database connection functions that specify default values
will use those values in place of any user-supplied arguments. For details
on the default values, see the documentation for the relevant connection
functions.
Warning
This feature has been REMOVED as of PHP 7.2.0.
Windows Specific
Here's a short explanation of
the configuration directives.
-
windows.show_crt_warning
bool
-
This directive shows the Windows CRT warnings when enabled.
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