Re: ACCESS TO SYSTEM VARIABLES

[Georg Bauhaus <rm.dash-bauhaus@futureapps.de>]

On 07.03.11 10:34, Emile8 wrote:

> with Ada.Environment_Variables; use Ada.Environment_Variables;
> with Ada.Text_Io; use Ada.Text_Io;
> 
> procedure Print_Env is
> begin
> Put_Line("Columns : " & Value("COLUMNS"));
> Put_Line("Lines : " & Value("LINES"));
> Put_Line("Path : " & Value("PATH"));
> end Print_Env;
> 
> 
> I would like to understand the reasons of this behavior. Are there
> different kinds of system variables in Linux ? Those as HOME, PATH
> whose values depend only on the user session and those as LINES,
> COLUMNS defined for each used terminal. Is there a way in Ada to
> overcome this limitation ?

Variables LINES and COLUMNS might not have been marked for export.
Try export -p.

With the above program, I see constraint errors for LINES and
COLUMNS when these don't exist in the environment (which is
expected behavior).

$ LINES=$LINES COLUMNS=$COLUMNS ./print_env
Columns : 255
Lines : 42
Path : /usr/local/bin:/usr/bin:/bin:/usr/games