PHP Manual
Prev | Chapter 4. Configuration | Next

# Configuration directives

## Httpd Options

Table 4-2. Httpd Options

Name | Default | Changeable
--- | --- | ---
async_send | "0" | PHP_INI_ALL

## Language Options

Table 4-3. Language and Misc Configuration Options

Name | Default | Changeable
--- | --- | ---
short_open_tag | On | PHP_INI_SYSTEM|PHP_INI_PERDIR
asp_tags | Off | PHP_INI_SYSTEM|PHP_INI_PERDIR
precision | "14" | PHP_INI_ALL
y2k_compliance | Off | PHP_INI_ALL
allow_call_time_pass_reference | On | PHP_INI_SYSTEM|PHP_INI_PERDIR
expose_php | On | PHP_INI_SYSTEM

Here is 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.

  > Note: Support for ASP-style tags was added in 3.0.4.

`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 enable the ability to force arguments to be 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, and the argument will be passed by value instead of by reference).

  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.

## Resource Limits

Table 4-4. Resource Limits

Name | Default | Changeable
--- | --- | ---
memory_limit | "8M" | PHP_INI_ALL

Here is 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.

See also: max_execution_time.

## Data Handling

Table 4-5. Data Handling Configuration Options

Name | Default | Changeable
--- | --- | ---
track-vars | "On" | PHP_INI_??
arg_separator.output | "&" | PHP_INI_ALL
arg_separator.input | "&" | PHP_INI_SYSTEM|PHP_INI_PERDIR
variables_order | "EGPCS" | PHP_INI_ALL
register_globals | "Off" | PHP_INI_PERDIR|PHP_INI_SYSTEM
register_argc_argv | "On" | PHP_INI_PERDIR|PHP_INI_SYSTEM
post_max_size | "8M" | PHP_INI_SYSTEM|PHP_INI_PERDIR
gpc_order | "GPC" | PHP_INI_ALL
auto_prepend_file | "" | PHP_INI_SYSTEM|PHP_INI_PERDIR
auto_append_file | "" | PHP_INI_SYSTEM|PHP_INI_PERDIR
default_mimetype | "text/html" | PHP_INI_ALL
default_charset | "iso-8859-1" | PHP_INI_ALL
always_populate_raw_post_data | "0" | PHP_INI_SYSTEM|PHP_INI_PERDIR
allow_webdav_methods | "0" | PHP_INI_SYSTEM|PHP_INI_PERDIR

Here is 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

  Set the order of the EGPCS (Environment, GET, POST, Cookie, Server) variable parsing. The default setting of this directive is "EGPCS". Setting this to "GP", for example, will cause PHP to completely ignore environment variables, cookies and server variables, and to overwrite any GET method variables with POST-method variables of the same name.

  See also register_globals.

`register_globals` boolean

  Tells whether or not to register the EGPCS (Environment, GET, POST, Cookie, Server) variables as global variables. For example; if register_globals = on, the url `http://www.example.com/test.php?id=3` will produce `$id`. Or, `$DOCUMENT_ROOT` from `$_SERVER['DOCUMENT_ROOT']`. You may want to turn this off if you don't want to clutter your scripts' global scope with user data. As of PHP 4.2.0, this directive defaults to off. It's preferred to go through PHP Predefined Variables instead, such as the superglobals: `$_ENV`, `$_GET`, `$_POST`, `$_COOKIE`, and `$_SERVER`. 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 on`.

  > Note: register_globals is affected by the variables_order directive.

`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.

`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`.

`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 include() 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 include() 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 4.0b4, 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 variable.

`allow_webdav_methods` boolean

  Allow handling of WebDAV http requests within PHP scripts (eg. PROPFIND, PROPPATCH, MOVE, COPY, etc..) 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

Table 4-6. Paths and Directories Configuration Options

Name | Default | Changeable
--- | --- | ---
include_path | PHP_INCLUDE_PATH | PHP_INI_ALL
doc_root | PHP_INCLUDE_PATH | PHP_INI_SYSTEM
user_dir | NULL | PHP_INI_SYSTEM
extension_dir | PHP_EXTENSION_DIR | PHP_INI_SYSTEM
cgi.force_redirect | "1" | PHP_INI_SYSTEM
cgi.redirect_status_env | "" | PHP_INI_SYSTEM
fastcgi.impersonate | "0" | PHP_INI_SYSTEM

Here is a short explanation of the configuration directives.

`include_path` string

  Specifies a list of directories where the require(), include() and fopen_with_path() 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 4-3. UNIX include_path
      include_path=.:/home/httpd/php-lib

  Example 4-4. Windows include_path
      include_path=".;c:\www\phplib"

  The default value for this directive is `.` (only 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.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.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.

## File Uploads

Table 4-7. File Uploads Configuration Options

Name | Default | Changeable
--- | --- | ---
file_uploads | "1" | PHP_INI_SYSTEM
upload_tmp_dir | NULL | PHP_INI_SYSTEM
upload_max_filesize | "2M" | PHP_INI_SYSTEM|PHP_INI_PERDIR

Here is 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.

`upload_max_filesize` integer

  The maximum size of an uploaded file.

## General SQL

Table 4-8. General SQL Configuration Options

Name | Default | Changeable
--- | --- | ---
sql.safe_mode | "0" | PHP_INI_SYSTEM

Here is a short explanation of the configuration directives.

`sql.safe_mode` boolean

## Debugger Configuration Directives

`debugger.host` string

  DNS name or IP address of host used by the debugger.

`debugger.port` string

  Port number used by the debugger.

`debugger.enabled` boolean

  Whether the debugger is enabled.

Prev | Home | Next
How to change configuration settings | Up | Security