ACCESS(2)                            BSD                             ACCESS(2)



NAME
     access - determine accessibility of file

SYNOPSIS
     #include <sys/file.h>

     #define R_OK    4/* test for read permission */
     #define W_OK    2/* test for write permission */
     #define X_OK    1/* test for execute (search) permission */
     #define F_OK    0/* test for presence of file */

     accessible = access(path, mode)
     int accessible;
     char *path;
     int mode;

DESCRIPTION
     access checks the given file path for accessibility according to mode,
     which is an inclusive or of the bits R_OK, W_OK, and X_OK.  Specifying
     mode as F_OK (that is, 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 access, but an attempt to open it for writing will fail
     (although files can be created there); a file may look executable, but
     execve will fail unless it is in proper format.

ERRORS
     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.

     [ENAMETOOLONG]   A component of a pathname exceeded 255 characters, or an
                      entire pathname exceeded 1023 characters.

     [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 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
                      permissions checked with respect to the "other" mode

                      bits.

     [EFAULT]         path points outside the process' allocated address
                      space.

     [EIO]            An I/O error occurred while reading from or writing to
                      the file system.

SEE ALSO
     chmod(2), stat(2)

DIAGNOSTICS
     If path 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.

NOTES
     Some implementations return the error [EINVAL] if path contains a
     character with the high-order bit set.