2.9BSD/usr/man/cat2/access.2

ACCESS(2)           UNIX Programmer's Manual            ACCESS(2)

NAME
     access - determine accessibility of file

SYNOPSIS
     #include <sys/types.h>
     #include <sys/file.h>

     access(name, mode)
     char *name;

DESCRIPTION
     _A_c_c_e_s_s checks the given file _n_a_m_e for accessibility accord-
     ing to _m_o_d_e, which is FACCESS_READ (read), FACCESS_WRITE
     (write), or FACCESS_EXECUTE (execute) or a combination
     thereof.  Specifying FACCESS_EXISTS tests whether the direc-
     tories leading to the file can be searched and the file
     exists.

     An appropriate error indication is returned if _n_a_m_e 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 _e_r_r_n_o.  Zero 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 programs.

     Notice that it is only access bits that are checked.  A
     directory may be announced as writable by _a_c_c_e_s_s, but an
     attempt to open it for writing will fail (although files may
     be created there); a file may look executable, but _e_x_e_c will
     fail unless it is in proper format.

ERRORS
     _A_c_c_e_s_s to the file is denied if one or more of the following
     is true:

     [ENOTDIR]           A component of the path prefix is not a
                         directory.

     [ENOENT]            Read, write, or execute (search) permis-
                         sion is requested for a null path name
                         or the named file does not exist.

     [EINVAL]            The _n_a_m_e argument contained a non-ASCII
                         byte.

     [ELOOP]             Too many symbolic links were encountered
                         in translating the path name.

     [EROFS]             Write access is requested for a file on

Printed 7/30/83                                                 1

ACCESS(2)           UNIX Programmer's Manual            ACCESS(2)

                         a read-only file system.

     [ETXTBSY]           Write access is requested for a pure
                         procedure (shared text) file that is
                         being executed.

     [EACCES]            Permission bits of the file mode do not
                         permit the requested access; or search
                         permission is denied on a component of
                         the path prefix.  The owner of a file
                         has permission checked with respect to
                         the ``owner'' read, write, and execute
                         mode bits.  Members of the file's group
                         other than the owner have permission
                         checked with respect to the ``group''
                         mode bits, and all others have permis-
                         sions checked with respect to the
                         ``other'' mode bits.

     [EFAULT]            _N_a_m_e points outside the process's allo-
                         cated address space.

BUGS
     The test for execute permission may be successful even
     though _n_a_m_e is a shared text file which is currently open
     for reading and therefore not executable.  The super-user is
     always granted execute permission even though 1) execute
     permission is meaningful only for directories and regular
     files, and 2) _e_x_e_c requires that at least one execute mode
     bit be set for a regular file to be executable.

SEE ALSO
     chmod(2), execve(2), stat(2)

ASSEMBLER
     (access = 33.)
     sys access; name; mode

Printed 7/30/83                                                 2