Hướng dẫn dùng exited synonyms trong PHP

(PHP 4, PHP 5, PHP 7, PHP 8)

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exitOutput a message and terminate the current script

Description

exit(string $status = ?): void

exit(int $status): void

exit is a language construct and it can be called without parentheses if no status is passed.

Parameters

status

If status is a string, this function prints the status just before exiting.

If status is an int, that value will be used as the exit status and not printed. Exit statuses should be in the range 0 to 254, the exit status 255 is reserved by PHP and shall not be used. The status 0 is used to terminate the program successfully.

Return Values

No value is returned.

Examples

Example #1 exit example

$filename

'/path/to/data-file';
$file fopen($filename'r')
    or exit(
"unable to open file ($filename)");?>

Example #2 exit status example

//exit program normally
exit;
exit();
exit(
0);//exit with an error code
exit(1);
exit(
0376); //octal?>

Example #3 Shutdown functions and destructors run regardless

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.';
?>

The above example will output:

 Shutdown: shutdown()
 Destruct: Foo::__destruct()
 

albert at removethis dot peschar dot net

13 years ago

jbezorg at gmail proposed the following:

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:

if($_SERVER['SCRIPT_FILENAME'] == __FILE__)
{
 
header('Location: /');
  exit;
}
?>

dexen dot devries at gmail dot com

11 years ago

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.

// 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()?>

theonenkl at gmail dot com

7 years ago

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:

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

vincent dot laag at gmail dot com

11 years ago

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.

void a t informance d o t info

13 years ago

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:
define ('INDEX', true);
?>

in your included file:
if (!defined('INDEX')) {
   die(
'You cannot call this script directly !');
}
?>

BR.

Ninj

emils at tvnet dot lv

19 years ago

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.

sunfundev at gmail dot com

5 years ago

>> 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:
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:
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
?>

m dot libergolis at gmail dot com

7 years ago

In addition to "void a t informance d o t info", here's a one-liner that requires no constant:

($_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:

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:

($_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.

alexyam at live dot com

10 years ago

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:

    echo "You have to wait 10 seconds to see this.
"
;
   
register_shutdown_function('shutdown');
    exit;
    function
shutdown(){
       
sleep(10);
        echo
"Because exit() doesn't terminate php-fpm calls immediately.
"
;
    }
?>

This doesn't:

    echo "You can see this from the browser immediately.
"
;
   
fastcgi_finish_request();
   
sleep(10);
    echo
"You can't see this form the browser.";
?>

devinemke at devinemke dot com

20 years ago

If you are using templates with numerous includes then exit() will end you script and your template will not complete (no

, , 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');

chris at ocproducts dot com

4 years ago

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.

powtac at gmx de

4 years ago

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.

shaun at NOshatSPAM dot net

20 years ago

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.

matt at serverboy dot net

12 years ago

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:

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:
switch(true) {
    case
true:
        require(
'application.php');
}
?>

application.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.

kehaovista at qq dot com

6 years ago

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()

Alexander Behling

1 year ago

it is also possible to include function calls e.g. logging function to write the error in a log file.

e.g.

function logerror($error){
file_put_contents(__DIR__.'/error_log', 'Error occured: '.$error');
}

die(logerror('error msg here');

This will terminate the script and write "error msg here" to error.log

You could use this for example when query the database to log when the query fails.

programming php

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