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Date: Sat, 31 Oct 2015 00:19:16 +0100
From: Xavier Petit <xpetit@becoast.fr>
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Newsgroups: comp.lang.ada
Subject: Re: Help with constructing an Ada Shell
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Xref: news.eternal-september.org comp.lang.ada:28144
Date: 2015-10-31T00:19:16+01:00
List-Id: <comp.lang.ada>

Hello, I would suggest you to learn Ada with more easy and abstract 
stuff, not shells ^^ which are platform dependent and related to the 
Unix/C philosophy.
GNAT provides OS abstraction but I think that dealing with process 
spawning is not the best way to learn Ada.

Here a working example of what you wanna do, based on previous answers.
(Sorry for my terrible english)

with Ada.Text_IO,
      GNAT.OS_Lib;

procedure Ada_Shell is
    procedure Execute_System (Command : String)
    is
       use GNAT.OS_Lib;

       List : String_List_Access := Argument_String_To_List (Command);
       Exec_Path : String_Access := Locate_Exec_On_Path (List (1).all);
       Success : Boolean;

    begin
       if Exec_Path /= null then
          Spawn (Program_Name => Exec_Path.all,
                 Args         => List (2 .. List'Last),
                 Success      => Success);
          Free (Exec_Path);
       else
          Ada.Text_IO.Put_Line ("Command not found");
       end if;

       Free (List);
    end Execute_System;

begin
    Main : loop
       Ada.Text_IO.Put ("ash> ");

       declare
          Input : constant String := Ada.Text_IO.Get_Line;
       begin
          exit Main when Input = "exit";

          if Input'Length > 0 then
             Execute_System (Command => Input);
          end if;
       end;
    end loop Main;

exception
    when Ada.Text_IO.End_Error => null; -- Handling [Ctrl]-[D]
end Ada_Shell;

-- 
Xavier Petit