Stdout from program

[tomek]

Is there any way to catch/redirect stdout of program in program ?
I want to get like debugln messages in my app (as ex. in Memo component) ? Something like catch self stdout.

[eny]

Not tested, but maybe this does the trick:
http://stackoverflow.com/questions/1060591/opening-a-tstream-on-stdin-stdout-in-a-delphi-console-app

[Leledumbo]

wiki.lazarus.freepascal.org/Executing_External_Programs

[tomek]

@leledumbo, you do not understand me, I want to catch self output.

@eny, thanks for hint, but it doesn't work, I also try with:

Code: [Select]

GetStdHandle(STD_OUTPUT_HANDLE)
 ReadConsoleOutputCharacter
and it's work only with nogui app (without -WG) or if I use AllocConsole before GetStdHandle(STD_OUTPUT_HANDLE).
It seams that it will work only with console.
I wonder how can help  --debug-log application parameter, which probably redirects STDOUT.

[eny]

The question is: why do want to access stdout?
If it's for logging purposes it might be better to use a logging package like log4delphi (which has a FPC port).

[theo]

Or this:
http://wiki.lazarus.freepascal.org/MultiLog

[tomek]

The question is: why do want to access stdout?
...

I use dll in the program, that dll provides only output as "print to stdout". And I want to have this output in gui app (without console). That's the problem.

[eny]

Google reveals this link: http://stackoverflow.com/questions/2639144/delphi-capture-stdout-and-stderr-output-from-statically-linked-msvc-compiled
That might help.

[tomek]

Google reveals this link: http://stackoverflow.com/questions/2639144/delphi-capture-stdout-and-stderr-output-from-statically-linked-msvc-compiled
That might help.

THANKS. That's it.
I use with Pipe, CreatePipe and SetStdHandle(STD_OUTPUT_HANDLE, hWriteToPipe) and I have output wherever I want. 

[mirco]

I use with Pipe, CreatePipe and SetStdHandle(STD_OUTPUT_HANDLE, hWriteToPipe) and I have output wherever I want. 

Could you share your solution, please?
Thank you.

[Gyuri]

Hello forum members,

For some reason I can't create a new topic, so I am continuing here, since I found it the most appropriate to my problem.

I am using a 32 bit dll on 64 bit Windows. The dll is sending status information to stdout. With inspiration from this topic, and these two:
https://stackoverflow.com/questions/43291343/receive-and-handle-windows-messages-in-lazarus
https://www.tek-tips.com/forums/102/faqs/7402

I was able to "capture/redirect" the stdout, and be able to process it with my GUI application. I used pipes, and read in a thread. Here is the code snippet (full code of the monitor unit attached in the zip archive) of the creation and read function.

Code: Pascal  [Select][+][-]

1. constructor TSTDIOMonitor.Create(AOwner: TComponent);
2. var
3.   Security: TSecurityAttributes;
4. begin
5.   inherited Create(AOwner);
6.   with Security do
7.   begin
8.     nlength := SizeOf(TSecurityAttributes) ;
9.     binherithandle := true;
10.     lpsecuritydescriptor := nil;
11.   end;
12.   CreatePipe(InputPipeRead, InputPipeWrite, @Security, 0);
13.   CreatePipe(OutputPipeRead, OutputPipeWrite, @Security, 0);
14.   CreatePipe(ErrorPipeRead, ErrorPipeWrite, @Security, 0);
15.   SetStdHandle(STD_INPUT_HANDLE, InputPipeRead);
16.   SetStdHandle(STD_OUTPUT_HANDLE, OutputPipeWrite);
17.   SetStdHandle(STD_ERROR_HANDLE, ErrorPipeWrite);
18.   FStringList := TStringList.Create;
19.   ReadThread  := TReadThread.Create;
20.   ReadThread.Enabled    := False;
21.   ReadThread.StringList := FStringList;
22.   ReadThread.OnUpdate   := @DoUpdate;
23.   ReadThread.Start;
24. end;
25.  

Code: Pascal  [Select][+][-]

1. procedure TReadThread.Execute;
2. var
3.   BytesRem: Integer;
4. begin
5.   while not Terminated do
6.   begin
7.     if FEnabled then
8.     begin
9.       BytesRem := 0;
10.       FTextString := ReadPipeInput(OutputPipeRead, BytesRem);
11.       if FTextString <> '' then
12.          Synchronize(@DoUpdate);
13.       FTextString := ReadPipeInput(ErrorPipeRead, BytesRem);
14.       if FTextString <> '' then
15.          Synchronize(@DoUpdate);
16.     end;
17.     sleep(40);
18.   end;
19. end;
20.  

Code: Pascal  [Select][+][-]

1. function ReadPipeInput(aInputPipe: THandle; var aBytesRem: Integer): String;
2. var
3.   vTextBuffer: array[1..32767] of char;
4.   vTextString: String;
5.   vBytesRead: DWORD;
6.   vPipeSize: Integer;
7. begin
8.   Result := '';
9.   vPipeSize := Sizeof(vTextBuffer);
10.   PeekNamedPipe(aInputPipe, nil, vPipeSize, @vBytesRead, @vPipeSize, @aBytesRem);
11.   if vBytesRead > 0 then
12.   begin
13.     ReadFile(aInputPipe, vTextBuffer, vPipeSize, vBytesRead, nil);
14.     OemToChar(@vTextBuffer, @vTextBuffer);
15.     vTextString := String(vTextBuffer);
16.     SetLength(vTextString, vBytesRead);
17.     Result := vTextString;
18.   end;
19. end;
20.  

Everything was fine as long I was running the application from the IDE. Accessing the dll's functions is also working fine, I receive all the necessary status information. I had the greatest surprise, when I started my application directly from the Windows environment. The stdio redirection/capturing is not working. Obviously I am making an elementary mistake, but it seems  am not able to find it.

I would really appreciate your help.

Thanks in advance,
Gyorgy

PS, also for some unknown reasons, I am not able to attach the zip archive