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 — Obtener y/o establecer el nombre de la sesión actual
Descripción
session_name
([ string
$name
] ) : string
session_name() devuelve el nombre de la sesión
actual. Si se da el nombre name,
session_name() actualizará el nombre de la sesión y devolverá
el nombre antiguo de la sesión.
El nombre de la sesión se reinicia al valor predeterminado almacenado en session.name en el momento de iniciar una petición. Por lo tanto, se necesita llamar a session_name() por cada petición (y antes de llamar a session_start() o session_register()).
Parámetros
-
name -
El nombre de la sesión hace referencia al nombre de la sesión usado cookies y URLs (p.ej. PHPSESSID). Debería contener sólo caracteres alfanuméricos; debería ser corto y descriptivo (esto es, para usuarios con las advertencias de cookies habilitadas). Si se especifica
name, el nombre de la sesión actual se cambia por su valor.AdvertenciaEl nombre de la sesión no puede consistir en dígitos solamente, debe de estar presente al menos una letra. De otro modo se genera un nuevo id de sesión cada vez.
Valores devueltos
Devuelve el nombre de la sesión actual. Si se proporciona name
y una función actualiza el nombre de la sesión, se devolverá el nombre
antiguo de la sesión.
Ejemplos
Ejemplo #1 Ejemplo de session_name()
<?php
/* establecer el nombre de la sesión a WebsiteID */
$nombre_anterior = session_name("WebsiteID");
echo "El nombre anterior de la sesión era $nombre_anterior<br />";
?>
add a note
User Contributed Notes 8 notes
Hongliang Qiang ¶
14 years ago
php at wiz dot cx ¶
10 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 ¶
9 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.
Joseph Dalrymple ¶
7 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.
Victor H ¶
3 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!
tony at marston-home dot demon dot co dot uk ¶
7 months 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 ¶
7 months 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 ¶
14 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
