absolute_file_name(+Spec, 
-Absolute, +Options)(library(lists)), a 
relative filename or an absolute filename. The primary intention of this 
predicate is to resolve files specified as Alias(Relative), which use
file_search_path/2 
to look up the possibilities for Alias. This predicate only returns 
non-directories, unless the option
file_type(directory) is specified or the requested access 
is none. Supported Options are:
.ext or 
plain ext.read, write, append, execute,
search, exist or none. See also access_file/2. 
The default is none which, if file_type is not 
specified as directory or regular, returns 
absolute file names that result from expanding aliases without 
inspecting the actual file system.txt implies [''],
prolog implies ['.pl',’’], executable 
implies
['.so',’’] and qlf implies ['.qlf',’’]. 
The
Type directory implies [''] and 
causes this predicate to generate (only) directories. The Type regular 
is the opposite of directory and is the default if no file 
type is specified and the effective access mode is none.
The file type source is an alias for prolog 
for compatibility with SICStus Prolog. See also prolog_file_type/2.
error (default), throw an existence_error 
exception if the file cannot be found. If fail, stay 
silent.159Silent operation was the 
default up to version 3.2.6.first (default), the predicate leaves no choice point. 
Otherwise a choice point will be left and backtracking may yield more 
solutions.true (default is false) and Spec 
is atomic, call expand_file_name/2 
followed by member/2 
on Spec before proceeding. This is a SWI-Prolog extension 
intended to minimise porting effort after SWI-Prolog stopped expanding 
environment variables and the ~ by default. 
This option should be considered deprecated. In particular the use of wildcard 
patterns such as * should be avoided.
The Prolog flag verbose_file_search 
can be set to true to help debugging Prolog's search for 
files. See also file_search_path/2.
This predicate is derived from Quintus Prolog. In Quintus Prolog, the 
argument order was absolute_file_name(+Spec, +Options, -Path). 
The argument order has been changed for compatibility with ISO and 
SICStus. The Quintus argument order is still accepted.