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From: gisle@krake.ii.uib.no (Gisle S{lensminde)
Subject: Re: Reading environment variables in ADA?
Date: 1998/09/17
Message-ID: <slrn702qlt.f3k.gisle@krake.ii.uib.no>#1/1
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References: <6tdl75$qs6$2@nyheter.chalmers.se>
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Organization: University of Bergen, Norway
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Newsgroups: comp.lang.ada
Date: 1998-09-17T00:00:00+00:00
List-Id: <comp.lang.ada>

In article <6tdl75$qs6$2@nyheter.chalmers.se>, Stefan Lingdell wrote:
>How do you read environment variables in ADA? I'm
>programming under UNIX (SunOS) if that makes any
>difference.
>
>Thanks,
>Stefan
>

There is packages to access environment variables and other OS things.
Since this is a posix feature, you can use the florist package, If have
thought to use a lot of OS features, that is a good idea. If not, you
can use the C interface. The program under reads the HOME
environment variable, and demonstrates how the C interface can be used
for this. I have tested it for solaris/gnat, but should work on all
Unix systems. If you use other compilers than GNAT, you maybe must 
link with the C library.  

The example:

with Interfaces.C.Strings;  
use type Interfaces.C.Strings.Chars_Ptr;
with Ada.Text_IO; use Ada.Text_IO;

procedure env is 

   package Cstr renames Interfaces.C.strings;

   function Getenv(Name : Cstr.Chars_Ptr) return Cstr.Chars_Ptr; 
   pragma Import(C, Getenv);

   Var_Name, Result : Cstr.Chars_Ptr;

begin
   Var_Name := Cstr.New_String("HOME");
   Result := Getenv(Var_Name);
   Cstr.Free(Var_Name);
   if Result /= Cstr.Null_Ptr then
      Put_Line(Cstr.Value(Result));
   end if;
end;
 

-- 
------------------------------------------------------------------------
  Gisle S�lensminde                Tlf:   55 34 07 63
  Eliasmarken 16                   
  5031 Laksev�g                    epost: gisle@ii.uib.no   

  UNIX is user friendly. It's just selective about who its friends are.
------------------------------------------------------------------------