ACCESS(2) System Calls Manual ACCESS(2)
access - determine accessibility of file
Access checks the given file name for accessibility according to mode,
which is 4 (read), 2 (write) or 1 (execute) or a combination thereof.
Specifying mode 0 tests whether the directories leading to the file can
be searched and the file exists.
An appropriate error indication is returned if name cannot be found or
if any of the desired access modes would not be granted. On disallowed
accesses -1 is returned and the error code is in errno. 0 is returned
from successful tests.
The user and group IDs with respect to which permission is checked are
the real UID and GID of the process, so this call is useful to set-UID
Notice that it is only access bits that are checked. A directory may
be announced as writable by access, but an attempt to open it for writ-
ing will fail (although files may be created there); a file may look
executable, but exec will fail unless it is in proper format.
(access = 33.)
sys access; name; mode