[Solution] 'failed' to open stream: Permission denied in ...... 'Summary of php usage

1. the file to be opened does not exist

Ii. Permission issues:

1.This PHP application is generally intended for general users in linux. The directory should be readable, writable, and executable (that is, 777). The file is assigned the corresponding permissions of general users according to the corresponding operations.

Eg: Put the file under/usr/local/a/. The file name is a.txt and the file operation is 'r +'

Directory a permission: chmod 777

The permission for file a.txt should at least be: chmod 006 a.txt

2.If the file is under/root/, even if the file and Its Directory have 777 permissions, the Permission denied error message will appear.