What should I do if I modify upload_tmp_dir?

The modification of upload_tmp_dir does not work. in php. ini, I set upload_tmp_dir to a custom temporary directory, and restart apache. the result of phpinfo () is also the directory I set. The temporary directory where files can be uploaded is the default/tmp. why? My settings in php. ini are as follows: why does PHPcodeuploa modify upload_tmp_dir?
In php. ini, I set upload_tmp_dir to a customized temporary directory, restart apache, and the result of phpinfo () is also the directory I set.
The temporary directory where files can be uploaded is the default/tmp. why?
My settings in php. ini are as follows:

PHP code

  Upload_tmp_dir = '/var/www/tmp'

Ubuntu 11.10 + Apache/2.2.20 (Ubuntu) + PHP 5.3.6-13ubuntu3. 6

------ Solution --------------------
Check whether phpinfo has been set successfully. Confirm that all users have write permission on/var/www/tmp.
------ Solution --------------------
Discussion

Check whether phpinfo has been set successfully. Confirm that all users have write permission on/var/www/tmp.