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Miscellaneous configuration directives
This is not a complete list of PHP directives. Directives are listed
in their appropriate locations so for example information on session
directives is located in the
sessions chapter.
Httpd Options
Table 4-2. Httpd Options Name | Default | Changeable |
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async_send | "0" | PHP_INI_ALL |
Language Options
Table 4-3. Language and Misc Configuration Options Name | Default | Changeable |
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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's 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 |
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memory_limit | "8M" | PHP_INI_ALL |
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. 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.
As of PHP 4.3.2, and when memory_limit is enabled, the PHP function
memory_get_usage() is made available.
See also: max_execution_time.
Data Handling
Table 4-5. Data Handling Configuration Options Name | Default | Changeable |
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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 | register_long_arrays | "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'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
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.
- 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.
- 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.
- 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 |
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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.fix_pathinfo | "0" | PHP_INI_SYSTEM | cgi.force_redirect | "1" | PHP_INI_SYSTEM | cgi.redirect_status_env | "" | PHP_INI_SYSTEM | fastcgi.impersonate | "0" | PHP_INI_SYSTEM | cgi.rfc2616_headers | "0" | PHP_INI_SYSTEM |
Here's 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" |
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Example 4-4. Windows include_path include_path=".;c:\php\includes" |
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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.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 it's paths to conform to the
spec. A setting of zero causes PHP to behave as before. Default
is zero. 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.
- 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
Table 4-7. File Uploads Configuration Options Name | Default | Changeable |
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file_uploads | "1" | PHP_INI_SYSTEM | upload_tmp_dir | NULL | PHP_INI_SYSTEM | upload_max_filesize | "2M" | PHP_INI_SYSTEM|PHP_INI_PERDIR |
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.
- 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 |
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sql.safe_mode | "0" | PHP_INI_SYSTEM |
Here's a short explanation of
the configuration directives.
Debugger Configuration DirectivesCaution |
Only PHP 3 implements a default debugger, for more information see Appendix E.
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- 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.
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