Httpd Options

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 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. 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.

In PHP5, allow_call_time_pass_reference is deprecated, in versions prior to PHP 5.3.0, use of this feature will emit an E_COMPILE_WARNING, and in PHP 5.3.0+, the warning is a E_DEPRECATED notice.

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.

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. 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.

Note: Availability note
This directive became available in PHP 4.3.2

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.

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.

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

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

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. 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.

Warning

This feature has been DEPRECATED as of PHP 5.3.0. Relying on this feature is highly discouraged.

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

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

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.

open_basedir string

Limit the files that can be opened 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 open a file with, for example, fopen() or gzopen(), the location of the file is checked. When the file is outside the specified directory-tree, PHP will refuse to open 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.

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 actually a prefix, not a directory name. This means that "open_basedir = /dir/incl" also allows 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()

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

Absolute path to 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.

zend_extension_debug_ts string

Variant of zend_extension for extensions compiled with debug info and thread safety.

zend_extension_ts string

Variant of zend_extension for extensions compiled with thread safety.

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: 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.

fastcgi.logging boolean

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

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

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.

max_file_uploads integer

The maximum number of files allowed to be uploaded simultaneously.

General SQL

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.