command working in terminal but working from code php

1Things that i tried were : 
21. Try executing the simple command fist and see if the out is comming.
3  example : system('ls -l > output.txt') // This will output the file in public 
4    										//folder
52. After that i tried giving the permission 777 to the files and folder 
6    that require and access and create a file.
7    example : chmod -R 777 /var/www/html/PATH_TO_FOLDER/public
8      
93. Search your php.ini with this commands: php --ini
10  For Me: Loaded Configuration File: /etc/php/7.2/cli/php.ini
11	In your php.ini file, set variables_order = "EGPCS".