how long does a session variable stay set?

sneakyimp

i'm making a wizard-type series of pages. the first page gathers and validates data and redirects on success to page 2 which gathers more data, etc. i'm storing the data from page 1 in a session variable so that i can get it on subsequent pages.

if i do this on page 1

session_start();
$_SESSION['reg_data'] = serialize($foo);
header("Location: page2.php");

how long is that session value there? will it still be there until i unset it? if the user navigates to other pages, will it still be defined?

devinemke

using the the default php.ini settings:
session propagation is done via cookies. the cookies will be set until the user closes their browser. the actaul session file on the server will be flagged for deletion after 1440 seconds of inactivity.

sneakyimp

thanks for your reply.

so even if the user access a hundred other pages (on my site or elsewhere) in 24 minutes, whatever vars i have set in $_SESSION should still be intact--provided that the session is intact (i.e., the session id doesn't somehow change or some cleanup on the server happens)??

devinemke

Originally posted by sneakyimp
...i.e., the session id doesn't somehow change or some cleanup on the server happens??

PHP has it's own garbage collection routine which is controlled by the following php.ini settings:

session.gc_divisor
session.gc_maxlifetime
session.gc_probability

read up on these here

sneakyimp

you rock!

i've actually seen the session lifetime thing...there's like a x% chance per page access that the sessions will get cleaned up.

i'm finding it hard to believe that session vars are basically set and forget. it seems a bit incredible that my first page might set some session var which will stick around until i get rid of it or the session ends.

seems too good to be true.

thanks.