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

NAME
     access - check access permissions of a file or pathname

SYNOPSIS
     #include <unistd.h>

     int
     access(const char *path, int mode);

DESCRIPTION
     The access() function checks the accessibility of the file named by path
     for the access permissions indicated by mode.  The value of mode is the
     bitwise inclusive OR of the access permissions to be checked (R_OK for
     read permission, W_OK for write permission, and X_OK for execute/search
     permission) or the existence test, F_OK.  All components of the pathname
     path are checked for access permissions (including F_OK).

     The real user ID is used in place of the effective user ID and the real
     group access list (including the real group ID) is used in place of the
     effective ID for verifying permission.

     If the invoking process has superuser privileges, access() will always
     indicate success for R_OK and W_OK, regardless of the actual file
     permission bits.  Likewise, for X_OK, if the file has any of the execute
     bits set and path is not a directory, access() will indicate success.

RETURN VALUES
     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.

ERRORS
     Access to the file is denied if:

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

     [ENAMETOOLONG]
		   A component of a pathname exceeded {NAME_MAX} characters,
		   or an entire path name exceeded {PATH_MAX} characters.

     [ENOENT]	   The named file does not exist.

     [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 presently 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.

     [EPERM]	   Write access has been requested and the named file has its
		   immutable flag set (see chflags(2)).

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

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

     [EINVAL]	   An invalid value was specified for mode.

SEE ALSO
     chmod(2), stat(2)

STANDARDS
     The access() function conforms to IEEE Std 1003.1-1990 (``POSIX'').

CAVEATS
     access() should never be used for actual access control.  Doing so can
     result in a time of check vs. time of use security hole.

OpenBSD 4.9			 June 10, 2008			   OpenBSD 4.9

Vote for polarhome