How to use/obtain output from system commands (in an Ada program) ?

How to use/obtain output from system commands (in an Ada program) ?

[reinkor]

Hi,

I am looking for a simple way to obtain output from "xmessage"
(or dialog/kdialog) in my Ada program. Any good hints?

A trivial way is to output to a file like in this test procedure:

with Interfaces.C;
with Interfaces.C.Strings;
with Ada.Text_IO, Text_IO;

procedure Test7 is
   package C renames Interfaces.C;
   use type C.char_array;
   procedure system (Source : in  C.char_array);
   pragma Import(C, system, "system");
   use Ada.Text_IO, Text_IO;
   file1 : File_Type;
begin
     system("xmessage -center Box1  -buttons label1:X,label2:y -print > choice_file1");
     Open(file1,In_File,"choice_file1");
     declare
      A : String := Get_Line(file1);
     begin
      Put(" Choice: " & A);
     end;
     Close(file1);
end Test7;

Are there more direct/better ways?

** By the way: when I run this program on Raspberry Pi 
(lastest Raspbian jessie) i get, as expected, created the file "choice_file1".
Under OpenSuse Leap 42.1, gnat-5, i get produced a file named:
"choice_file1choice_file1test7.adb". Strange?

reinert

Re: How to use/obtain output from system commands (in an Ada program) ?

[Dmitry A. Kazakov]

On 2016-06-19 08:08, reinkor wrote:

> I am looking for a simple way to obtain output from "xmessage"
> (or dialog/kdialog) in my Ada program. Any good hints?

The package System.OS_Lib has procedures Spawn that are much more 
comfortable to use than system().

If you use GtkAda you can start xmessage or any other process with 
pipe-lined input/output/error. Then you will have callbacks to process 
them. It is also possible to use Gtk_Text_Buffer instead of callbacks.

http://www.dmitry-kazakov.de/ada/gtkada_contributions.htm#10.1

> A trivial way is to output to a file like in this test procedure:
>
> with Interfaces.C;
> with Interfaces.C.Strings;
> with Ada.Text_IO, Text_IO;
>
> procedure Test7 is
>    package C renames Interfaces.C;
>    use type C.char_array;
>    procedure system (Source : in  C.char_array);
>    pragma Import(C, system, "system");
>    use Ada.Text_IO, Text_IO;
>    file1 : File_Type;
> begin
>      system("xmessage -center Box1  -buttons label1:X,label2:y -print > choice_file1");

Add terminating ASCII NUL here.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: How to use/obtain output from system commands (in an Ada program) ?

[reinkor]

Thanks a lot,

any hint about rpm/repository for gtkada on OpenSuse (Leap) ?

reinert


On Sunday, June 19, 2016 at 9:24:16 AM UTC+2, Dmitry A. Kazakov wrote:
> On 2016-06-19 08:08, reinkor wrote:
> 
> > I am looking for a simple way to obtain output from "xmessage"
> > (or dialog/kdialog) in my Ada program. Any good hints?
> 
> The package System.OS_Lib has procedures Spawn that are much more 
> comfortable to use than system().
> 
> If you use GtkAda you can start xmessage or any other process with 
> pipe-lined input/output/error. Then you will have callbacks to process 
> them. It is also possible to use Gtk_Text_Buffer instead of callbacks.
> 
> http://www.dmitry-kazakov.de/ada/gtkada_contributions.htm#10.1
> 
> > A trivial way is to output to a file like in this test procedure:
> >
> > with Interfaces.C;
> > with Interfaces.C.Strings;
> > with Ada.Text_IO, Text_IO;
> >
> > procedure Test7 is
> >    package C renames Interfaces.C;
> >    use type C.char_array;
> >    procedure system (Source : in  C.char_array);
> >    pragma Import(C, system, "system");
> >    use Ada.Text_IO, Text_IO;
> >    file1 : File_Type;
> > begin
> >      system("xmessage -center Box1  -buttons label1:X,label2:y -print > choice_file1");
> 
> Add terminating ASCII NUL here.
> 
> -- 
> Regards,
> Dmitry A. Kazakov
> http://www.dmitry-kazakov.de

Re: How to use/obtain output from system commands (in an Ada program) ?

[Dmitry A. Kazakov]

On 20/06/2016 10:34, reinkor wrote:

> any hint about rpm/repository for gtkada on OpenSuse (Leap) ?

Would Fedora's RPM go?

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: How to use/obtain output from system commands (in an Ada program) ?

[reinkor]

Have little time to be too experimental now :-)

reinert

On Monday, June 20, 2016 at 10:45:20 AM UTC+2, Dmitry A. Kazakov wrote:
> On 20/06/2016 10:34, reinkor wrote:
> 
> > any hint about rpm/repository for gtkada on OpenSuse (Leap) ?
> 
> Would Fedora's RPM go?
> 
> -- 
> Regards,
> Dmitry A. Kazakov
> http://www.dmitry-kazakov.de

Re: How to use/obtain output from system commands (in an Ada program) ?

[Dmitry A. Kazakov]

On 20/06/2016 11:22, reinkor wrote:
> Have little time to be too experimental now :-)

Does not using Suse fall into the category? (:-))

You could build GtkAda from sources, it is not as challenging under 
Linux as under Windows.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: How to use/obtain output from system commands (in an Ada program) ?

[reinkor]

Debian could be less experimental?  Ubuntu?

reinert

On Monday, June 20, 2016 at 11:59:48 AM UTC+2, Dmitry A. Kazakov wrote:
> On 20/06/2016 11:22, reinkor wrote:
> > Have little time to be too experimental now :-)
> 
> Does not using Suse fall into the category? (:-))
> 
> You could build GtkAda from sources, it is not as challenging under 
> Linux as under Windows.
> 
> -- 
> Regards,
> Dmitry A. Kazakov
> http://www.dmitry-kazakov.de

Re: How to use/obtain output from system commands (in an Ada program) ?

[Dmitry A. Kazakov]

On 2016-06-20 21:25, reinkor wrote:
> Debian could be less experimental?

Debian has GtkAda 3.8.3 packaged.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: How to use/obtain output from system commands (in an Ada program) ?

[briot.emmanuel]

> > I am looking for a simple way to obtain output from "xmessage"
> > (or dialog/kdialog) in my Ada program. Any good hints?

Look at the package GNAT.Expect, which is meant to spawn an
executable while keeping pipes for its input and output. You do not have
to go through a file for this.
It is used by GPS to spawn compiler, interactive debugger,...