posix_access() checks the user's permission of a file.
file
The name of the file to be tested.
mode
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.
Bemærk: Når safe mode er aktiveret, checker PHP om filerne eller bibliotekerne som du er ved at benytte, har det samme UID (owner) som scriptet der bliver eksekveret.