shams

When i run this code: <?php $bar = 'BAR'; apc_store('foo', $bar); var_dump(apc_fetch('foo')); ?> get this error: PHP Fatal error: Uncaught Error: Call to undefined function apc_store() This is phpinfo() for apcu: APCu Support Enabled Version 5.1.21 APCu Debugging Disabled MMAP Support Enabled MMAP File Mask no value Serialization Support php Build Date Jan 4 2022 17:27:51 Directive Local Value Master Value apc.coredump_unmap Off Off apc.enable_cli Off Off apc.enabled On On apc.entries_hint 4096 4096 apc.gc_ttl 3600 3600 apc.mmap_file_mask no value no value apc.preload_path no value no value apc.serializer php php apc.shm_segments 1 1 apc.shm_size 32M 32M apc.slam_defense Off Off apc.smart 0 0 apc.ttl 0 0 apc.use_request_time Off Off

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