php cannot wirte to external usb hard drive?

[shams]

In ubuntu 18.10 ,  i created a folder name db in the external usb hard dirve changed the ownership to the www-data the apache2 server and set the permissions to 777 , i run this php code and get the permission error:

<php
 chdir('/media/user/e46cafba-2656-4e42-b1c9-6417f28839df/db/');
 system('./rs');
?>    

but the php code cannot change to the dir and get the error:

[21-Feb-2019 10:43:26 UTC] PHP Warning:  chdir(): Permission denied (errno 13) in /home/user/www/html/rse4db.php on line 5

 

[gw1500se]

First using 777 is very dangerous so you really don't want those permissions. Second, just because the directory 'db' has those permissions, it does not mean the upper level directories have the correct ownership or permissions. You have to look at each level.