ACCESS(2) UNIX Programmer's Manual ACCESS(2) NNAAMMEE access - determine accessibility of file SSYYNNOOPPSSIISS ##iinncclluuddee <<ssyyss//ffiillee..hh>> ##ddeeffiinnee RR__OOKK 44//** tteesstt ffoorr rreeaadd ppeerrmmiissssiioonn **// ##ddeeffiinnee WW__OOKK 22//** tteesstt ffoorr wwrriittee ppeerrmmiissssiioonn **// ##ddeeffiinnee XX__OOKK 11//** tteesstt ffoorr eexxeeccuuttee ((sseeaarrcchh)) ppeerrmmiissssiioonn **// ##ddeeffiinnee FF__OOKK 00//** tteesstt ffoorr pprreesseennccee ooff ffiillee **// aacccceessssiibbllee == aacccceessss((ppaatthh,, mmooddee)) iinntt aacccceessssiibbllee;; cchhaarr **ppaatthh;; iinntt mmooddee;; DDEESSCCRRIIPPTTIIOONN _A_c_c_e_s_s checks the given file _p_a_t_h for accessibility accord- ing to _m_o_d_e, which is an inclusive or of the bits R_OK, W_OK and X_OK. Specifying _m_o_d_e as F_OK (i.e., 0) tests whether the directories leading to the file can be searched and the file exists. The real user ID and the group access list (including the real group ID) are used in verifying permission, so this call is useful to set-UID programs. Notice that only access bits are checked. A directory may be indicated 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_v_e will fail unless it is in proper format. RREETTUURRNN VVAALLUUEE If _p_a_t_h cannot be found or if any of the desired access modes would not be granted, then a -1 value is returned; otherwise a 0 value is returned. EERRRROORRSS Access to the file is denied if one or more of the following are true: [ENOTDIR] A component of the path prefix is not a directory. [EINVAL] The pathname contains a character with the high-order bit set. [ENAMETOOLONG] A component of a pathname exceeded 255 char- acters, or an entire path name exceeded 1023 characters. Printed 7/9/88 May 22, 1986 1 ACCESS(2) UNIX Programmer's Manual ACCESS(2) [ENOENT] The named file does not exist. [EACCES] Search permission is denied for a component of the path prefix. [ELOOP] Too many symbolic links were encountered in translating the pathname. [EROFS] Write access is requested for a file on a read-only file system. [ETXTBSY] Write access is requested for a pure pro- cedure (shared text) file that is being exe- cuted. [EACCES] Permission bits of the file mode do not per- mit the requested access, or search permis- sion 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 per- mission checked with respect to the ``group'' mode bits, and all others have permissions checked with respect to the ``other'' mode bits. [EFAULT] _P_a_t_h points outside the process's allocated address space. [EIO] An I/O error occurred while reading from or writing to the file system. SSEEEE AALLSSOO chmod(2), stat(2) Printed 7/9/88 May 22, 1986 2