The configuration file (called php3.ini in PHP 3.0, and simply php.ini as of PHP 4.0) is read when PHP starts up. For the server module versions of PHP, this happens only once when the web server is started. For the CGI and CLI version, it happens on every invocation.
The default location of php.ini is a compile time option (see the FAQ entry), but can be changed for the CGI and CLI version with the -c command line switch, see the chapter about using PHP from the command line. You can also use the environment variable PHPRC for an additional path to search for a php.ini file.
Not every PHP directive is documented below. For a list of all directives, please read your well commented php.ini file. You may want to view the latest php.ini here from CVS.
Example 4-1. php.ini example
When using PHP as an Apache module, you can also change the configuration settings using directives in Apache configuration files and .htaccess files (You will need "AllowOverride Options" or "AllowOverride All" privileges)
With PHP 3.0, there are Apache directives that correspond to each configuration setting in the php3.ini name, except the name is prefixed by "php3_".
With PHP 4.0, there are several Apache directives that allow you to change the PHP configuration from within the Apache configuration file itself.
This sets the value of the specified variable.
This is used to set a Boolean configuration option.
This sets the value of the specified variable. "Admin" configuration settings can only be set from within the main Apache configuration files, and not from .htaccess files.
This is used to set a Boolean configuration option.
Note: PHP constants do not exist outside of PHP. For example, in httpd.conf do not use PHP constants such as E_ALL or E_NOTICE to set the error_reporting directive as they will have no meaning and will evaluate to 0. Use the associated bitmask values instead. These constants can be used in php.ini
This option enables the URL-aware fopen wrappers that enable accessing URL object like files. Default wrappers are provided for the access of remote files using the ftp or http protocol, some extensions like zlib may register additional wrappers.
Note: This option was introduced immediately after the release of version 4.0.3. For versions up to and including 4.0.3 you can only disable this feature at compile time by using the configuration switch --disable-url-fopen-wrapper.
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.
The special value none disables auto-appending.
Note: If the script is terminated with exit(), auto-append will not occur.
The special value none disables auto-prepending.
This directive must be set in php.ini For example, you cannot set this in httpd.conf.
This determines whether errors should be printed to the screen as part of the HTML output or not.
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.
This directive is really only useful in the Apache module version of PHP. It is used by sites that would like to turn PHP parsing on and off on a per-directory or per-virtual server basis. By putting engine off in the appropriate places in the httpd.conf file, PHP can be enabled or disabled.
Name of file where script errors should be logged. If the special value syslog is used, the errors are sent to the system logger instead. On UNIX, this means syslog(3) and on Windows NT it means the event log. The system logger is not supported on Windows 95.
Set the error reporting level. The parameter is either an integer representing a bit field, or named constants. The error_reporting levels and constants are described in the Error Handling section of the manual, and in php.ini. To set at runtime, use the error_reporting() function. See also the display_errors directive.
The default value does not show E_NOTICE level errors. You may want to show them during development.
Turn off HTML tags in error messages. The new format for html errors produces clickable messages that direct the user to a page describing the error or function in causing the error. These references are affected by docref_root and docref_ext.
The new error format contains a reference to a page describing the error or function in causing the error. In case of manual pages you can download the manual in your language and set this ini directive to the url of your local copy. If your local copy of the manual can be reached by '/manual/' you can simply use docref_root=/manual/. Additional you have to set docref_ext to match the fileextensions of your copy docref_ext=.html. It is possible to use external references. For example you can use docref_root=http://manual/en/.
Note: The value of docref_root must end with a slash '/'.
Note: The value of docref_ext must begin with a dot '.'.
Limit the files that can be opened by PHP to the specified directory-tree.
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.
The special value . indicates that the directory in which the script is stored will be used as base-directory.
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/"
Note: Support for multiple directories was added in 3.0.7.
The default is to allow all files to be opened.
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, that this option is not available in PHP 4. Use variables_order instead.
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.
TRUE by default. If changed to FALSE scripts will be terminated as soon as they try to output something after a client has aborted their connection.
See also ignore_user_abort().
FALSE by default. Changing this to TRUE tells PHP to tell the output layer to flush itself automatically after every output block. This is equivalent to calling the PHP function flush() after each and every call to print() or echo() and each and every HTML block.
When using PHP within an web environment, turning this option on has serious performance implications and is generally recommended for debugging purposes only. This value defaults to TRUE when operating under the CLI SAPI.
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.
Tells whether script error messages should be logged to the server's error log. This option is thus server-specific.
Sets the magic_quotes state for GPC (Get/Post/Cookie) operations. When magic_quotes are on, all ' (single-quote), " (double quote), \ (backslash) and NUL's are escaped with a backslash automatically. If magic_quotes_sybase is also on, a single-quote is escaped with a single-quote instead of a backslash.
If magic_quotes_runtime is enabled, most functions that return data from any sort of external source including databases and text files will have quotes escaped with a backslash. If magic_quotes_sybase is also on, a single-quote is escaped with a single-quote instead of a backslash.
If magic_quotes_sybase is also on, a single-quote is escaped with a single-quote instead of a backslash if magic_quotes_gpc or magic_quotes_runtime is enabled.
This sets the maximum time in seconds a script is allowed to run before it is terminated by the parser. This helps prevent poorly written scripts from tying up the server. The default setting is 30.
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.
The number of significant digits displayed in floating point numbers.
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.
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.
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.
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.
If enabled, the last error message will always be present in the global variable $php_errormsg.
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.
The temporary directory used for storing files when doing file upload. Must be writable by whatever user PHP is running as.
The maximum size of an uploaded file. The value is in bytes.
The base name of the directory used on a user's home directory for PHP files, for example public_html.
If enabled, this option makes PHP output a warning when the plus (+) operator is used on strings. This is to make it easier to find scripts that need to be rewritten to using the string concatenator instead (.).
Whether to use UID (FALSE) or GID (TRUE) checking upon file access. See Safe Mode for more information.
If PHP is used in safe mode, system() and the other functions executing system programs refuse to start programs that are not in this directory.
UID/GID checks are bypassed when including files from this directory and its subdirectories (directory must also be in include_path or full path must including).
As of PHP 4.2.0, this directive can take on a semi-colon separated path in a similar fashion to the include_path directive, rather than just a single directory.
This directive is really only useful in the Apache module version of PHP. You can turn dynamic loading of PHP extensions with dl() on and off per virtual server or per directory.
The main reason for turning dynamic loading off is security. With dynamic loading, it's possible to ignore all the safe_mode and open_basedir restrictions.
The default is to allow dynamic loading, except when using safe-mode. In safe-mode, it's always imposible to use dl().
In what directory PHP should look for dynamically loadable extensions.
Which dynamically loadable extensions to load when PHP starts up.
Name of BS2000 PLAM library containing the loadable SESAM driver modules. Required for using SESAM functions. The BS2000 PLAM library must be set ACCESS=READ,SHARE=YES because it must be readable by the apache server's user id.
Name of SESAM application configuration file. Required for using SESAM functions. The BS2000 file must be readable by the apache server's user id.
The application configuration file will usually contain a configuration like (see SESAM reference manual):
Name of SESAM message catalog file. In most cases, this directive is not neccessary. Only if the SESAM message file is not installed in the system's BS2000 message file table, it can be set with this directive.
The message catalog must be set ACCESS=READ,SHARE=YES because it must be readable by the apache server's user id.