posix_access() checks the user's permission of a file.
The name of the file to be tested.
A mask consisting of one or more of POSIX_F_OK, POSIX_R_OK, POSIX_W_OK and POSIX_X_OK. Defaults to POSIX_F_OK.
POSIX_R_OK, POSIX_W_OK and POSIX_X_OK request checking whether the file exists and has read, write and execute permissions, respectively. POSIX_F_OK just requests checking for the existence of the file.
Example 1. posix_access() example
This example will check if the $file is readable and writable, otherwise will print an error message.
Note: When safe mode is enabled, PHP checks whether the files or directories you are about to operate on have the same UID (owner) as the script that is being executed.