(PHP 4, PHP 5)
session_name — Get and/or set the current session name
$name
] )
session_name() returns the name of the current
session. If name is given,
session_name() will update the session name and return
the old session name.
The session name is reset to the default value stored in session.name at request startup time. Thus, you need to call session_name() for every request (and before session_start() or session_register() are called).
name
The session name references the name of the session, which is
used in cookies and URLs (e.g. PHPSESSID). It
should contain only alphanumeric characters; it should be short and
descriptive (i.e. for users with enabled cookie warnings).
If name is specified, the name of the current
session is changed to its value.
The session name can't consist of digits only, at least one letter must be present. Otherwise a new session id is generated every time.
Returns the name of the current session.
Example #1 session_name() example
<?php
/* set the session name to WebsiteID */
$previous_name = session_name("WebsiteID");
echo "The previous session name was $previous_name<br />";
?>
Joseph Dalrymple (2011-04-14 23:52:38)
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.
relsqui at chiliahedron dot com (2009-02-20 23:07:47)
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.
php at wiz dot cx (2008-09-27 20:36:43)
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.
webmaster at nncoders dot de (2008-06-26 09:29:03)
You can always just use "or".
@foo or bar();
When foo fails, (and the at still means don't print an error to the browser), the function bar will be executed.
<?php
function errorhandler () { /* do something wild */ }
@session_name('mysession') or errorhandler();
?>
Another live example would be
@mysql_query('show databases') or die(mysql_error());
When the execution fails, parameter die is called (with last mysql_error as given string parameter)
slave at codegrunt dot com (2004-12-22 14:03:36)
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
Hongliang Qiang (2004-05-27 13:48:51)
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.