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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. In order to use this directive you must have enabled it at compile time. So, your configure line would have included: --enable-memory-limit. Note that you have to set it to -1 if you don't want any limit for your memory.

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=".:/php/includes"

Example 4-4. Windows include_path

include_path=".;c:\php\includes"

Using a . in the include path allows for relative includes as it means 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.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.