1:- module(
    2  os_ext,
    3  [
    4    exists_program/1,  % +Program
    5    open_file/1,       % +File
    6    open_file/2,       % +MediaType, +File
    7    os/1,              % ?Os
    8    os_path/1,         % ?Directory
    9    process_create/2   % +Exe, +Args
   10  ]
   11).

   17:- use_module(library(process)).   18:- use_module(library(yall)).   19
   20:- use_module(library(file_ext)).   21:- use_module(library(media_type)).   22:- use_module(library(thread_ext)).

 exists_program(+Program:atom) is semidet

Succeeds if the given program can be run from PATH.

   32exists_program(Program) :-
   33  os_path(Prefix),
   34  atomic_list_concat([Prefix,Program], /, Exe),
   35  access_file(Exe, execute), !.

 open_file(+File:atom) is semidet

 open_file(+MediaType:media_type, +File:atom) is det

Open the file using the first existing program that is registered with the Media Type denote by its file name extension.

Fails if there is no file name extension, or if the file name extension cannot be mapped to a Media Type, or if the Media Type cannot be mapped to a program, or if none of the mapped to programs exists.

   50open_file(File) :-
   51  file_media_type(File, MediaType),
   52  open_file(MediaType, File).
   53
   54
   55open_file(MediaType, File) :-
   56  media_type_program(MediaType, Program, Args),
   57  exists_program(Program), !,
   58  process_create(path(Program), [file(File)|Args], []).

 os(+Os:oneof([mac,unix,windows])) is semidet

os(-Os:oneof([mac,unix,windows])) is det

Succeeds if Os denotes the current Operating System.

   67os(mac) :-
   68  current_prolog_flag(apple, true), !.
   69os(unix) :-
   70  current_prolog_flag(unix, true), !.
   71os(windows) :-
   72  current_prolog_flag(windows, true), !.

 os_path(+Directory:atom) is semidet

os_path(-Directory:atom) is nondet

Succeeds if Directory is on the OS PATH.

   81os_path(Dir) :-
   82  getenv('PATH', Path),
   83  os_path_separator(Sep),
   84  atomic_list_concat(Dirs0, Sep, Path),
   85  member(Dir0, Dirs0),
   86  prolog_to_os_filename(Dir, Dir0).

 os_path_separator(-Separator:oneof([:,;])) is det

   92os_path_separator(Sep) :-
   93  os(Os),
   94  os_path_separator(Os, Sep).
   95
   96os_path_separator(mac, :).
   97os_path_separator(unix, :).
   98os_path_separator(windows, ;).

 process_create(+Exe, +Args:list) is det

  104process_create(Exe, Args) :-
  105  process_create(Exe, Args, [])