help about execute a command

help about execute a command

[jtapasai]

I am learning ADA 95 with gnat 3.10 under linux, and I must write a program
that executes a command of the operating system such as ls,insmod , cp ... Is
that possible ? Thanks in advance !

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Re: help about execute a command

[Samuel Tardieu]

> I am learning ADA 95 with gnat 3.10 under linux, and I must write a
> program that executes a command of the operating system such as
> ls,insmod , cp ... Is that possible ? Thanks in advance !

This is really a FAQ... Here is an untested version of a function
(Spawn) which does this in Ada[1].

  Sam

Footnotes: 
[1]  Note the capitalization, it's not ADA
-- 
Samuel Tardieu -- sam@ada.eu.org

function Spawn (Command : String) return Integer;
--  Spawn a command and return its exit status

with Interfaces.C.Strings; use Interfaces.C, Interfaces.C.Strings;

function Spawn (Command : String) return Integer is
   function C_System (Command : chars_ptr) return int;
   pragma Import (C, C_System, "system");
   C_Command : chars_ptr    := New_String (Command);
   Code      : constant int := C_System (C_Command);
begin
   Free (C_Command);
   return Integer (Code / 256);
end Spawn;

Re: help about execute a command

[Jerry van Dijk]

jtapasai@my-dejanews.com wrote:

: I am learning ADA 95 with gnat 3.10 under linux, and I must write a program
: that executes a command of the operating system such as ls,insmod , cp ... Is
: that possible ? Thanks in advance !

with Interfaces.C;

procedure Show is

   function System (Cmd : String) return Integer is
      function C_System (S : Interfaces.C.char_array) return Integer;
      pragma Import (C, C_System, "system");
   begin
      return C_System (Interfaces.C.To_C (Cmd));	
   end System;
   pragma Inline (System);

   Result : Integer;
begin
   Result := System ("ls");
end Show;

I notice that the last three question you asked here could all have been 
easily answered by looking in the index of an good Ada reference book. I
suggest you really should get one of those books.
My own preference is for 'Ada as a second language' by Norman Cohen.

Jerry.

-- 
-- Jerry van Dijk  | email: jdijk@acm.org
-- Leiden, Holland | member Team-Ada
-- Ada & Win32: http://stad.dsl.nl/~jvandyk

Re: help about execute a command

[Robert Dewar]

jtapasai asks

<<I am learning ADA 95 with gnat 3.10 under linux, and I must write a program
that executes a command of the operating system such as ls,insmod , cp ... Is
that possible ? Thanks in advance !
>>

Have a look at GNAT.OS_Lib.Spawn (in file g-os_lib.ads).

In general if you are using GNAT, look through the g-??????.ads files, there
is quite a bit of useful stuff here, and we are constantly adding new
functionality to this specialized GNAT library.

Robert Dewar
Ada Core Technologies