When a object is passed as $status and it consists of a __toString() magic method the string value of this method will be used as $status. If the object does not contain a __toString method, exit will throw a catchable fatal error.
(PHP 4, PHP 5, PHP 7)
exit — 输出一个消息并且退出当前脚本
$status
] ) : void$status
) : void中止脚本的执行。 尽管调用了 exit()， Shutdown函数 以及 object destructors 总是会被执行。
exit 是个语法结构，如果没有 status 参数要传入，可以省略圆括号。
status
如果 status 是一个字符串，在退出之前该函数会打印
status 。
如果 status 是一个 integer，该值会作为退出状态码，并且不会被打印输出。
退出状态码应该在范围0至254，不应使用被PHP保留的退出状态码255。
状态码0用于成功中止程序。
没有返回值。
Example #1 exit() 例子
<?php
$filename = '/path/to/data-file';
$file = fopen($filename, 'r')
or exit("unable to open file ($filename)");
?>
Example #2 exit() 状态码例子
<?php
//exit program normally
exit;
exit();
exit(0);
//exit with an error code
exit(1);
exit(0376); //octal
?>
Example #3 无论如何，Shutdown函数与析构函数都会被执行
<?php
class Foo
{
public function __destruct()
{
echo 'Destruct: ' . __METHOD__ . '()' . PHP_EOL;
}
}
function shutdown()
{
echo 'Shutdown: ' . __FUNCTION__ . '()' . PHP_EOL;
}
$foo = new Foo();
register_shutdown_function('shutdown');
exit();
echo 'This will not be output.';
?>
以上例程会输出：
Shutdown: shutdown() Destruct: Foo::__destruct()
When a object is passed as $status and it consists of a __toString() magic method the string value of this method will be used as $status. If the object does not contain a __toString method, exit will throw a catchable fatal error.
Calling 'exit' will bypass the auto_append_file option.
On some free hosting this risks you getting removed, as they may be using for ads and analytics.
So be a bit careful if using this on the most common output branch.
Please note $status is printed to stdout, not stderr.
>> Shutdown functions and object destructors will always be executed even if exit is called.
It is false if you call exit into desctructor.
Normal exit:
<?php
class A
{
public function __destruct()
{
echo "bye A\n";
}
}
class B
{
public function __destruct()
{
echo "bye B\n";
}
}
$a = new A;
$b = new B;
exit;
// Output:
// bye B
// bye A
?>
// Exit into desctructor:
<?php
class A
{
public function __destruct()
{
echo "bye A\n";
}
}
class B
{
public function __destruct()
{
echo "bye B\n";
exit;
}
}
$a = new A;
$b = new B;
// Output:
// bye B
?>
<?php
class Foo
{
public function __construct()
{
register_shutdown_function([$this, 'shutdown']);
}
public function __destruct()
{
echo 'Destruct: ' . __METHOD__ . '()' . PHP_EOL;
}
function shutdown()
{
echo 'Shutdown: ' . __FUNCTION__ . '()' . PHP_EOL;
}
}
$foo = new Foo();
exit();
// output is
//Shutdown: shutdown()
//Destruct: Foo::__destruct()
In addition to "void a t informance d o t info", here's a one-liner that requires no constant:
<?php basename($_SERVER['PHP_SELF']) == basename(__FILE__) && die('Thou shall not pass!'); ?>
Placing it at the beginning of a PHP file will prevent direct access to the script.
To redirect to / instead of dying:
<?php
if (basename($_SERVER['PHP_SELF']) == basename(__FILE__)) {
if (ob_get_contents()) ob_clean(); // ob_get_contents() even works without active output buffering
header('Location: /');
die;
}
?>
Doing the same in a one-liner:
<?php basename($_SERVER['PHP_SELF']) == basename(__FILE__) && (!ob_get_contents() || ob_clean()) && header('Location: /') && die; ?>
A note to security: Even though $_SERVER['PHP_SELF'] comes from the user, it's safe to assume its validity, as the "manipulation" takes place _before_ the actual file execution, meaning that the string _must_ have been valid enough to execute the file. Also, basename() is binary safe, so you can safely rely on this function.
A side-note for the use of exit with finally: if you exit somewhere in a try block, the finally won't be executed. Could not sound obvious: for instance in Java you never issue an exit, at least a return in your controller; in PHP instead you could find yourself exiting from a controller method (e.g. in case you issue a redirect).
Here follows the POC:
<?php
echo "testing finally wit exit\n";
try {
echo "In try, exiting\n";
exit;
} catch(Exception $e) {
echo "catched\n";
} finally {
echo "in finally\n";
}
echo "In the end\n";
?>
This will print:
testing finally wit exit
In try, exiting
When using php-fpm, fastcgi_finish_request() should be used instead of register_shutdown_function() and exit()
For example, under nginx and php-fpm 5.3+, this will make browsers wait 10 seconds to show output:
<?php
echo "You have to wait 10 seconds to see this.<br>";
register_shutdown_function('shutdown');
exit;
function shutdown(){
sleep(10);
echo "Because exit() doesn't terminate php-fpm calls immediately.<br>";
}
?>
This doesn't:
<?php
echo "You can see this from the browser immediately.<br>";
fastcgi_finish_request();
sleep(10);
echo "You can't see this form the browser.";
?>
Calling to exit() will flush all buffers started by ob_start() to default output.
If you want to avoid calling exit() in FastCGI as per the comments below, but really, positively want to exit cleanly from nested function call or include, consider doing it the Python way:
define an exception named `SystemExit', throw it instead of calling exit() and catch it in index.php with an empty handler to finish script execution cleanly.
<?php
// file: index.php
class SystemExit extends Exception {}
try {
/* code code */
}
catch (SystemExit $e) { /* do nothing */ }
// end of file: index.php
// some deeply nested function or .php file
if (SOME_EXIT_CONDITION)
throw new SystemExit(); // instead of exit()
?>
Don't use the exit() function in the auto prepend file with fastcgi (linux/bsd os).
It has the effect of leaving opened files with for result at least a nice "Too many open files ..." error.
It should be noted that if building a site that runs on FastCGI, calling exit will generate an error in the server's log file. This can quickly fill up.
Also, using exit will diminish the performance benefit gained on FastCGI setups. Instead, consider using code like this:
<?php
if( /* error case */ )
echo "Invalid request";
else {
/* The rest of your application */
}
?>
I've also seen developers get around this issue with FastCGI by wrapping their code in a switch statement and using breaks:
index.php:
<?php
switch(true) {
case true:
require('application.php');
}
?>
application.php:
<?php
if($x > $y) {
echo "Sorry, that didn't work.";
break;
}
// ...
?>
It does carry some overhead, but compared to the alternative, it does the job well.
jbezorg at gmail proposed the following:
<?php
if($_SERVER['SCRIPT_FILENAME'] == __FILE__ )
header('Location: /');
?>
After sending the `Location:' header PHP _will_ continue parsing, and all code below the header() call will still be executed. So instead use:
<?php
if($_SERVER['SCRIPT_FILENAME'] == __FILE__)
{
header('Location: /');
exit;
}
?>
To rich dot lovely at klikzltd dot co dot uk:
Using a "@" before header() to suppress its error, and relying on the "headers already sent" error seems to me a very bad idea while building any serious website.
This is *not* a clean way to prevent a file from being called directly. At least this is not a secure method, as you rely on the presence of an exception sent by the parser at runtime.
I recommend using a more common way as defining a constant or assigning a variable with any value, and checking for its presence in the included script, like:
in index.php:
<?php
define ('INDEX', true);
?>
in your included file:
<?php
if (!defined('INDEX')) {
die('You cannot call this script directly !');
}
?>
BR.
Ninj
Note, that using exit() will explicitly cause Roxen webserver to die, if PHP is used as Roxen SAPI module. There is no known workaround for that, except not to use exit(). CGI versions of PHP are not affected.
return may be preferable to exit in certain situations, especially when dealing with the PHP binary and the shell.
I have a script which is the recipient of a mail alias, i.e. mail sent to that alias is piped to the script instead of being delivered to a mailbox. Using exit in this script resulted in the sender of the email getting a delivery failure notice. This was not the desired behavior, I wanted to silently discard messages which did not satisfy the script's requirements.
After several hours of trying to figure out what integer value I should pass to exit() to satisfy sendmail, I tried using return instead of exit. Worked like a charm. Sendmail didn't like exit but it was perfectly happy with return. So, if you're running into trouble with exit and other system binaries, try using return instead.
If you are using templates with numerous includes then exit() will end you script and your template will not complete (no </table>, </body>, </html> etc...). Rather than having complex nested conditional logic within your content, just create a "footer.php" file that closes all of your HTML and if you want to exit out of a script just include() the footer before you exit().
for example:
include ('header.php');
blah blah blah
if (!$mysql_connect) {
echo "unable to connect";
include ('footer.php');
exit;
}
blah blah blah
include ('footer.php');