This may sound no-brainer: the session_name() function will have no essential effect if you set session.auto_start to "true" in php.ini . And the obvious explanation is the session already started thus cannot be altered before the session_name() function--wherever it is in the script--is executed, same reason session_name needs to be called before session_start() as documented.
I know it is really not a big deal. But I had a quite hard time before figuring this out, and hope it might be helpful to someone like me.
session_name
(PHP 4, PHP 5, PHP 7)
session_name — Pobierz i/lub ustaw nazwę bieżącej sesji
Opis
session_name
([ string
$nazwa
] ) : string
session_name() zwraca nazwę bieżącej sesji. Jeśli
podano parametr name, nazwa bieżącej sesji
zostanie zmieniona na tą wartość.
Nazwa sesji jest używana w identyfikatorze sesji w ciasteczkach i URLach. Powinna zawierać tylko znaki alfanumeryczne; powinna być krótka i treściwa (np. dla użytkowników z włączonymi ostrzeżeniami o ciasteczkach). Nazwa sesji jest przywracana do domyślnej wartości określonej w session.name na początku wywołania strony, a więc musisz wywołać session_name() dla każdej strony (przed wywołaniem w niej session_start() i session_register()).
Ostrzeżenie
Nazwa sesji nie może składać się tylko z cyfr - musi zawierać przynajmniej jedną literę. W przeciwnym przypadku za każdym odwołaniem generowana będzie nowa sesja.
Przykład #1 Przykłady session_name()
<?php
/* ustaw nazwę sesji na WebsiteID */
$poprzednia_nazwa = session_name ("WebsiteID");
echo "Poprzednią nazwą sesji było $poprzednia_nazwa<br />";
?>
Zobacz także opis dyrektywy konfiguracji session.name.
add a note
User Contributed Notes 9 notes
Hongliang Qiang ¶
19 years ago
php at wiz dot cx ¶
15 years ago
if you try to name a php session "example.com" it gets converted to "example_com" and everything breaks.
don't use a period in your session name.
relsqui at chiliahedron dot com ¶
15 years ago
Remember, kids--you MUST use session_name() first if you want to use session_set_cookie_params() to, say, change the session timeout. Otherwise it won't work, won't give any error, and nothing in the documentation (that I've seen, anyway) will explain why.
Thanks to brandan of bildungsroman.com who left a note under session_set_cookie_params() explaining this or I'd probably still be throwing my hands up about it.
Victor H ¶
8 years ago
As Joseph Dalrymple said, adding session_name do slow down a little bit the execution time.
But, what i've observed is that it decreased the fluctuation between requests.
Requests on my script fluctuated between 0,045 and 0,022 seconds. With session_name("myapp"), it goes to 0,050 and 0,045. Not a big deal, but that's a point to note.
For those with problems setting the name, when session.auto_start is set to 1, you need to set the session.name on php.ini!
Joseph Dalrymple ¶
13 years ago
For those wondering, this function is expensive!
On a script that was executing in a consistent 0.0025 seconds, just the use of session_name("foo") shot my execution time up to ~0.09s. By simply sacrificing session_name("foo"), I sped my script up by roughly 0.09 seconds.
mmulej at gmail dot com ¶
3 years ago
Hope this is not out of php.net noting scope.
session_name('name') must be set before session_start() because the former changes ini settings and the latter reads them. For the same reason session_set_cookie_params($options) must be set before session_start() as well.
I find it best to do the following.
function is_session_started()
{
if (php_sapi_name() === 'cli')
return false;
if (version_compare(phpversion(), '5.4.0', '>='))
return session_status() === PHP_SESSION_ACTIVE;
return session_id() !== '';
}
if (!is_session_started()) {
session_name($session_name);
session_set_cookie_params($cookie_options);
session_start();
}
tony at marston-home dot demon dot co dot uk ¶
5 years ago
The description that session_name() gets and/or sets the name of the current session is technically wrong. It does nothing but deal with the value originally supplied by the session.name value within the php.ini file.
Thus:-
$name = session_name();
is functionally equivalent to
$name = ini_get('session.name');
and
session_name('newname);
is functionally equivalent to
ini_set('session.name','newname');
This also means that:
$old_name = session_name('newname');
is functionally equivalent to
$old_name = ini_set('session.name','newname');
The current value of session.name is not attached to a session until session_start() is called. Once session_start() has used session.name to lookup the session_id() in the cookie data the name becomes irrelevant as all further operations on the session data are keyed by the session_id().
Note that changing session.name while a session is currently active will not update the name in any session cookie. The new name does not take effect until the next call to session_start(), and this requires that the current session, which was created with the previous value for session.name, be closed.
tony at marston-home dot demon dot co dot uk ¶
5 years ago
The description has recently been modified to contain the statement "When new session name is supplied, session_name() modifies HTTP cookie". This is not correct as session_name() has never modified any cookie data. A change in session.name does not become effective until session_start() is called, and it is session_start() that creates the cookie if it does not already exist.
See the following bug report for details: https://bugs.php.net/bug.php?id=76413
slave at codegrunt dot com ¶
19 years ago
One gotcha I have noticed with session_name is that it will trigger a WARNING level error if the cookie or GET/POST variable value has something other than alphanumeric characters in it. If your site displays warnings and uses PHP sessions this may be a way to enumerate at least some of your scripts:
http://example.com/foo.php?session_name_here=(bad)
Warning: session_start(): The session id contains invalid characters, valid characters are only a-z, A-Z and 0-9 in /some/path/foo.php on line 666
I did not see anything in the docs suggesting that one had to sanitize the PHP session ID values before opening the session but that appears to be the case.
Unfortunately session_name() always returns true so you have to actually get to the point of assigning variables values before you know whether you have been passed bad session data (as far as I can see). After the error has been generated in other words.
Cheers
