Spawn : Get the output of the called program

Spawn : Get the output of the called program

[Jean-Baptiste CAMPESATO]

Hello,
I want to called a programm (like the Spawn Procedure in GNAT.OS_lib) but
i wannt to get the output fo this program.
Do you know how can i get the output with Spawn, or another
function/procedure to do that ?
Thanks

Re: Spawn : Get the output of the called program

[Jean-Baptiste CAMPESATO]

Le Wed, 06 Apr 2005 12:21:14 +0200, Jean-Baptiste CAMPESATO a ￜcritￜ:

> Hello,
> I want to called a programm (like the Spawn Procedure in GNAT.OS_lib) but
> i wannt to get the output fo this program.
> Do you know how can i get the output with Spawn, or another
> function/procedure to do that ?
> Thanks

ReHello,
I want to do that to create a "CGI Executer".
I want to set the Environement for the called CGI Program, execute this
program and get the output of this program.
Somebody have an example for me please ?
Thanks.

Re: Spawn : Get the output of the called program

[Pascal Obry]

Jean-Baptiste CAMPESATO <camje_lemon@a2lf.org> writes:

> ReHello,
> I want to do that to create a "CGI Executer".

GNAT.Expects.

But are you really trying to build CGI ? This is an obsolete framework for Web
developpement, see AWS for something more up-to-date.

Pascal.

-- 

--|------------------------------------------------------
--| Pascal Obry                           Team-Ada Member
--| 45, rue Gabriel Peri - 78114 Magny Les Hameaux FRANCE
--|------------------------------------------------------
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--| "The best way to travel is by means of imagination"
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Re: Spawn : Get the output of the called program

[Jean-Baptiste CAMPESATO]

Le Wed, 06 Apr 2005 13:15:04 +0200, Pascal Obry a ￜcritￜ:

> 
> Jean-Baptiste CAMPESATO <camje_lemon@a2lf.org> writes:
> 
>> ReHello,
>> I want to do that to create a "CGI Executer".
> 
> GNAT.Expects.
> 
> But are you really trying to build CGI ? This is an obsolete framework for Web
> developpement, see AWS for something more up-to-date.
> 
> Pascal.

thanks for Expect.
Yes i want to use a CGI Executer, i want to create a Ada Very Light Http
Daemon :p.
Without using AWS, for a personal exercice.
Thanks.

Re: Spawn : Get the output of the called program

[Martin Krischik]

Jean-Baptiste CAMPESATO wrote:

> Le Wed, 06 Apr 2005 12:21:14 +0200, Jean-Baptiste CAMPESATO a ￜcritￜ:
> 
>> Hello,
>> I want to called a programm (like the Spawn Procedure in GNAT.OS_lib) but
>> i wannt to get the output fo this program.
>> Do you know how can i get the output with Spawn, or another
>> function/procedure to do that ?
>> Thanks
> 
> ReHello,
> I want to do that to create a "CGI Executer".
> I want to set the Environement for the called CGI Program, execute this
> program and get the output of this program.
> Somebody have an example for me please ?

As I said AdaCL (adacl.sf.net). However, AdaCL also got a complete CGI
framework - no need to write your own.

Martin 

-- 
mailto://krischik@users.sourceforge.net
Ada programming at: http://ada.krischik.com

Re: Spawn : Get the output of the called program

[Martin Krischik]

Jean-Baptiste CAMPESATO wrote:

> Hello,
> I want to called a programm (like the Spawn Procedure in GNAT.OS_lib) but
> i wannt to get the output fo this program.

No you need a special library which attaches pipes to stdin  and stdout.

> Do you know how can i get the output with Spawn, or another
> function/procedure to do that ?

AdaCL (adacl.sf.net) has got a package (AdaCL.OS.Command) which can do
exactly that.

Martin

-- 
mailto://krischik@users.sourceforge.net
Ada programming at: http://ada.krischik.com

Re: Spawn : Get the output of the called program

[Marc A. Criley]

Jean-Baptiste CAMPESATO wrote:
> Hello,
> I want to called a programm (like the Spawn Procedure in GNAT.OS_lib) but
> i wannt to get the output fo this program.
> Do you know how can i get the output with Spawn, or another
> function/procedure to do that ?
> Thanks

Jim Rogers' "Pipes" has long been my "go to" package whenever I need to 
spawn a program and capture its output for post-processing:

http://www.adapower.com/index.php?Command=Class&ClassID=Bindings&CID=181

Re: Spawn : Get the output of the called program

[Jean-Baptiste CAMPESATO]

Le Wed, 06 Apr 2005 12:21:14 +0200, Jean-Baptiste CAMPESATO a ￜcritￜ:

> Hello,
> I want to called a programm (like the Spawn Procedure in GNAT.OS_lib) but
> i wannt to get the output fo this program.
> Do you know how can i get the output with Spawn, or another
> function/procedure to do that ?
> Thanks

Thanks everybody :).
I will read http://adacl.sourceforge.net/ and a doc about pipes.

Re: Spawn : Get the output of the called program

[Dmitry A. Kazakov]

On Wed, 06 Apr 2005 16:43:31 +0200, Jean-Baptiste CAMPESATO wrote:

> Le Wed, 06 Apr 2005 12:21:14 +0200, Jean-Baptiste CAMPESATO a �crit�:
> 
>> I want to called a programm (like the Spawn Procedure in GNAT.OS_lib) but
>> i wannt to get the output fo this program.
>> Do you know how can i get the output with Spawn, or another
>> function/procedure to do that ?
>> Thanks
> 
> Thanks everybody :).
> I will read http://adacl.sourceforge.net/ and a doc about pipes.

I don't like the design of either library because many programs heavily use
stderr. For them to make it useful one needs all three pipes. Further, the
stderr pipe should be read out asynchronously from a parallel task.
Otherwise, you are risking to fall into a deadlock if the pipe buffer size
is limited, which is often the case. Therefore, you need two procedures:
Spawn to invoke the program and Wait to wait for its completion. Then when
you read from the stdout take care about End_Error. Normally after
End_Error, you just call Wait. Also the procedure Wait should raise an
exception if stderr was not empty.

P.S. We have implemented it for Unix/Posix with no GNAT.OS_lib, but alas it
is proprietary.

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

Re: Spawn : Get the output of the called program

[Martin Krischik]

Dmitry A. Kazakov wrote:

> On Wed, 06 Apr 2005 16:43:31 +0200, Jean-Baptiste CAMPESATO wrote:
> 
>> Le Wed, 06 Apr 2005 12:21:14 +0200, Jean-Baptiste CAMPESATO a ￜcritￜ:
>> 
>>> I want to called a programm (like the Spawn Procedure in GNAT.OS_lib)
>>> but i wannt to get the output fo this program.
>>> Do you know how can i get the output with Spawn, or another
>>> function/procedure to do that ?
>>> Thanks
>> 
>> Thanks everybody :).
>> I will read http://adacl.sourceforge.net/ and a doc about pipes.
> 
> I don't like the design of either library because many programs heavily
> use stderr. For them to make it useful one needs all three pipes.

Excuse me! I wrote AdaCL.OS.Command explicitly for that purpose - to attach
to all three pipes:

   --
   --  Attach a Text_IO file to the Standart Input of the process
   --
   procedure Attach_In (
      --  Object itself.
      This : in out Object'Class;
      --  Text IO to be attached
      File : in out Ada.Text_IO.File_Type);

   --
   --  Attach a Text_IO file to the Standart Output of the process
   --
   procedure Attach_Out (
      --  Object itself.
      This : in out Object'Class;
      --  Text IO to be attached
      File : in out Ada.Text_IO.File_Type);

   --
   --  Attach a Text_IO file to the Error Output of the process
   --
   procedure Attach_Error (
      --  Object itself.
      This : in out Object'Class;
      --  Text IO to be attached
      File : in out Ada.Text_IO.File_Type);

> Further,  
> the stderr pipe should be read out asynchronously from a parallel task.

And yes AdaCL.OS.Command has asynchronously execution as well:

   --
   --  Execution Mode
   --
   type Mode
   is (
      --  Start Process syncronous.
      Sync,
      --  Start Process asyncronous.
      Async,
      --  Start Process asyncronous and redirect standart in and
      --  standart out.
      In_Out);

> Otherwise, you are risking to fall into a deadlock if the pipe buffer size
> is limited, which is often the case. Therefore, you need two procedures:
> Spawn to invoke the program and Wait to wait for its completion.

   --
   --  Wait for the end of the command - only for Async and In_Out
   --
   procedure Wait (
      --  Object itself.
      This : in out Object);

I know that AdaCL is not perfect - but before you bash it you should at
least pick some feature which really isn't there.

Martin
-- 
mailto://krischik@users.sourceforge.net
Ada programming at: http://ada.krischik.com

Re: Spawn : Get the output of the called program

[Dmitry A. Kazakov]

On Wed, 06 Apr 2005 19:08:07 +0200, Martin Krischik wrote:

> Dmitry A. Kazakov wrote:
> 
>> On Wed, 06 Apr 2005 16:43:31 +0200, Jean-Baptiste CAMPESATO wrote:
>> 
>>> Le Wed, 06 Apr 2005 12:21:14 +0200, Jean-Baptiste CAMPESATO a �crit�:
>>> 
>>>> I want to called a programm (like the Spawn Procedure in GNAT.OS_lib)
>>>> but i wannt to get the output fo this program.
>>>> Do you know how can i get the output with Spawn, or another
>>>> function/procedure to do that ?
>>>> Thanks
>>> 
>>> Thanks everybody :).
>>> I will read http://adacl.sourceforge.net/ and a doc about pipes.
>> 
>> I don't like the design of either library because many programs heavily
>> use stderr. For them to make it useful one needs all three pipes.
> 
> Excuse me! I wrote AdaCL.OS.Command explicitly for that purpose - to attach
> to all three pipes:
> 
>    --
>    --  Attach a Text_IO file to the Standart Input of the process
>    --
>    procedure Attach_In (
>       --  Object itself.
>       This : in out Object'Class;
>       --  Text IO to be attached
>       File : in out Ada.Text_IO.File_Type);
> 
>    --
>    --  Attach a Text_IO file to the Standart Output of the process
>    --
>    procedure Attach_Out (
>       --  Object itself.
>       This : in out Object'Class;
>       --  Text IO to be attached
>       File : in out Ada.Text_IO.File_Type);
> 
>    --
>    --  Attach a Text_IO file to the Error Output of the process
>    --
>    procedure Attach_Error (
>       --  Object itself.
>       This : in out Object'Class;
>       --  Text IO to be attached
>       File : in out Ada.Text_IO.File_Type);
> 
>> Further,  
>> the stderr pipe should be read out asynchronously from a parallel task.
> 
> And yes AdaCL.OS.Command has asynchronously execution as well:
> 
>    --
>    --  Execution Mode
>    --
>    type Mode
>    is (
>       --  Start Process syncronous.
>       Sync,
>       --  Start Process asyncronous.
>       Async,
>       --  Start Process asyncronous and redirect standart in and
>       --  standart out.
>       In_Out);

And which one need to be used for stdin + stdout + stderr? What has In_Out
to do in the company of Sync/Async? Why the same object cannot be both Sync
and Async? If it cannot, then why this is not mapped to types? If it can,
why then there is one primitive operation for both modes?...

>> Otherwise, you are risking to fall into a deadlock if the pipe buffer size
>> is limited, which is often the case. Therefore, you need two procedures:
>> Spawn to invoke the program and Wait to wait for its completion.
> 
>    --
>    --  Wait for the end of the command - only for Async and In_Out
>    --
>    procedure Wait (
>       --  Object itself.
>       This : in out Object);
> 
> I know that AdaCL is not perfect - but before you bash it you should at
> least pick some feature which really isn't there.

I didn't critiqued a lack of features, but the design. It is still too low
level. After all, dup, dup2, fork, waitpid are also here...

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

Re: Spawn : Get the output of the called program

[Duncan Sands]

> I want to called a programm (like the Spawn Procedure in GNAT.OS_lib) but
> i wannt to get the output fo this program.
> Do you know how can i get the output with Spawn, or another
> function/procedure to do that ?

There's also something called "expect".  Check out g-expect.ads.

Ciao,

D.