The behaviour of these functions is affected by settings in php.ini.
Name | Default | Changeable | Changelog |
---|---|---|---|
output_buffering | "0" | PHP_INI_PERDIR | |
output_handler | NULL | PHP_INI_PERDIR | |
implicit_flush | "0" | PHP_INI_ALL | |
url_rewriter.tags | "a=href,area=href,frame=src,form=,fieldset=" | PHP_INI_ALL | Before PHP 7.1.0, this was used to set session's trans sid rewrite. From PHP 7.1.0, it is only used by output_add_rewrite_var(). |
url_rewriter.hosts | $_SERVER['HTTP_HOST'] is used as default. |
PHP_INI_ALL | Available as of PHP 7.1.0 |
Here's a short explanation of the configuration directives.
output_buffering
bool/int
You can enable output buffering for all files by setting this directive to 'On'. If you wish to limit the size of the buffer to a certain size - you can use a maximum number of bytes instead of 'On', as a value for this directive (e.g., output_buffering=4096). This directive is always Off in PHP-CLI.
output_handler
string
You can redirect all of the output of your scripts to a function. For example, if you set output_handler to mb_output_handler(), character encoding will be transparently converted to the specified encoding. Setting any output handler automatically turns on output buffering.
Note:
You cannot use both mb_output_handler() with ob_iconv_handler() and you cannot use both ob_gzhandler() and zlib.output_compression.
Note:
Only built-in functions can be used with this directive. For user defined functions, use ob_start().
implicit_flush
bool
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
.
See also ob_implicit_flush().
url_rewriter.tags
specifies which HTML tags
are rewritten by output_add_rewrite_var() values.
Defaults to
a=href,area=href,frame=src,input=src,form=
form
is special tag. <input hidden="session_id" name="session_name">
is added as form variable.
Note: Before PHP 7.1.0, url_rewriter.tags was used to specify session.trans_sid_tags. As of PHP 7.1.0,
fieldset
is no longer considered as special tag.
url_rewriter.hosts
string
url_rewriter.hosts
specifies which hosts are
rewritten to include output_add_rewrite_var() values.
Defaults to $_SERVER['HTTP_HOST']
. Multiple hosts
can be specified by ",", no space is allowed between hosts. e.g.
php.net,wiki.php.net,bugs.php.net