int access( const char *filename, int amode )

	- prototype in io.h

	- checks filename for existence & R/W access

	- amode = 06 -- check for R/W permission
		  04 -- check for R
		  02 -- check for W
		  01 -- execute (ignored)
		  00 -- check if filename exists

	- filename can be directory
	- returns 0 if OK
		 -1 on error
		    errno = ENOENT if path or filename not found
		    errno = EACCES if permission denied