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PHP Manual

## Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Errors and Logging Configuration Options
Name | Default | Changeable | Changelog
--- | --- | --- | ---
error_reporting | NULL | PHP_INI_ALL |
display_errors | "1" | PHP_INI_ALL |
display_startup_errors | "0" | PHP_INI_ALL |
log_errors | "0" | PHP_INI_ALL |
log_errors_max_len | "1024" | PHP_INI_ALL | Available since PHP 4.3.0.
ignore_repeated_errors | "0" | PHP_INI_ALL | Available since PHP 4.3.0.
ignore_repeated_source | "0" | PHP_INI_ALL | Available since PHP 4.3.0.
report_memleaks | "1" | PHP_INI_ALL | Available since PHP 4.3.0.
track_errors | "0" | PHP_INI_ALL |
html_errors | "1" | PHP_INI_ALL | PHP_INI_SYSTEM in PHP <= 4.2.3.
docref_root | "" | PHP_INI_ALL | Available since PHP 4.3.0.
docref_ext | "" | PHP_INI_ALL | Available since PHP 4.3.2.
error_prepend_string | NULL | PHP_INI_ALL |
error_append_string | NULL | PHP_INI_ALL |
error_log | NULL | PHP_INI_ALL |

For further details and definitions of the PHP_INI_* constants, see the php.ini directives.

Here's a short explanation of the configuration directives.

`error_reporting` integer

  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 Predefined Constants, and in php.ini. To set at runtime, use the error_reporting() function. See also the display_errors directive.

  In PHP 4 and PHP 5 the default value is E_ALL & ~E_NOTICE. This setting does not show `E_NOTICE` level errors. You may want to show them during development.

  > Note: Enabling `E_NOTICE` during development has some benefits. For debugging purposes: NOTICE messages will warn you about possible bugs in your code. For example, use of unassigned values is warned. It is extremely useful to find typos and to save time for debugging. NOTICE messages will warn you about bad style. For example, $arr[item] is better to be written as $arr['item'] since PHP tries to treat "item" as constant. If it is not a constant, PHP assumes it is a string index for the array.

  > Note: In PHP 5 a new error level `E_STRICT` is available. As `E_STRICT` is not included within `E_ALL` you have to explicitly enable this kind of error level. Enabling `E_STRICT` during development has some benefits. STRICT messages will help you to use the latest and greatest suggested method of coding, for example warn you about using deprecated functions.

  > Note: PHP Constants outside of PHP Using PHP Constants outside of PHP, like in httpd.conf, will have no useful meaning so in such cases the integer values are required. And since error levels will be added over time, the maximum value (for `E_ALL`) will likely change. So in place of `E_ALL` consider using a larger value to cover all bit fields from now and well into the future, a numeric value like 2147483647.

`display_errors` string

  This determines whether errors should be printed to the screen as part of the output or if they should be hidden from the user.

  Value "stderr" sends the errors to stderr instead of stdout. The value is available as of PHP 5.2.4. In earlier versions, this directive was of type boolean.

  > Note: This is a feature to support your development and should never be used on production systems (e.g. systems connected to the internet).

  > Note: Although display_errors may be set at runtime (with ini_set()), it won't have any affect if the script has fatal errors. This is because the desired runtime action does not get executed.

`display_startup_errors` boolean

  Even when display_errors is on, errors that occur during PHP's startup sequence are not displayed. It's strongly recommended to keep display_startup_errors off, except for debugging.

`log_errors` boolean

  Tells whether script error messages should be logged to the server's error log or error_log. This option is thus server-specific.

  > Note: You're strongly advised to use error logging in place of error displaying on production web sites.

`log_errors_max_len` integer

  Set the maximum length of log_errors in bytes. In error_log information about the source is added. The default is 1024 and 0 allows to not apply any maximum length at all. This length is applied to logged errors, displayed errors and also to $php_errormsg.

  When an integer is used, the value is measured in bytes. Shorthand notation, as described in this FAQ, may also be used.
`ignore_repeated_errors` boolean

  Do not log repeated messages. Repeated errors must occur in the same file on the same line until ignore_repeated_source is set true.

`ignore_repeated_source` boolean

  Ignore source of message when ignoring repeated messages. When this setting is On you will not log errors with repeated messages from different files or sourcelines.

`report_memleaks` boolean

  If this parameter is set to Off, then memory leaks will not be shown (on stdout or in the log). This has only effect in a debug compile, and if error_reporting includes E_WARNING in the allowed list

`track_errors` boolean

  If enabled, the last error message will always be present in the variable $php_errormsg.

`html_errors` boolean

  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.

`docref_root` string

  The new error format contains a reference to a page describing the error or function 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/` or `docref_root="http://landonize.it/?how=url&theme=classic&filter=Landon &url=http%3A%2F%2Fwww.php.net%2F"`

  Most of the time you want the docref_root value to end with a slash '/'. But see the second example above which does not have nor need it.

  > Note: This is a feature to support your development since it makes it easy to lookup a function description. However it should never be used on production systems (e.g. systems connected to the internet).

`docref_ext` string

  See docref_root.

  > Note: The value of docref_ext must begin with a dot '.'.

`error_prepend_string` string

  String to output before an error message.

`error_append_string` string

  String to output after an error message.

`error_log` string

  Name of the file where script errors should be logged. The file should be writable by the web server's user. 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. See also: syslog(). If this directive is not set, errors are sent to the SAPI error logger. For example, it is an error log in Apache or stderr in CLI.

Installation
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PHP Manual