posix_access() constants

注意:

Please note that some of these constants may not be available on every system.

POSIX_F_OK (int)

Check whether the file exists.

POSIX_R_OK (int)

Check whether the file exists and has read permissions.

POSIX_W_OK (int)

Check whether the file exists and has write permissions.

POSIX_X_OK (int)

Check whether the file exists and has execute permissions.