OK, since no one answers this in Lazarus forum, I'll ask here as it's more FPC (FCL, actually) related than LCL. I want to create an interactive process, so I need to read the output as soon as it's available and write it to the screen (or somewhere else). Here's the partial code (a little different from the original post to avoid visual component):

var
  CmdProcess: TProcess;
  MemStr: TMemoryStream;
  StrList: TStringList;
  n: Integer;
  ErrMsg: PChar;
begin
  try
    CmdProcess:=TProcess.Create(nil);
    MemStr:=TMemoryStream.Create;
    StrList:=TStringList.Create;
    MemStr.SetSize(READ_BYTES);
    with CmdProcess do begin
      CommandLine:=InputStr;
      Options:=[poUsePipes,poStderrToOutPut];
      ShowWindow:=swoHide;
      Execute;
      while Running do begin
        n:=Output.Read(MemStr.Memory^,READ_BYTES);
        if n>0 then begin
          StrList.LoadFromStream(MemStr);
          WriteLn(StrList.Text);
          MemStr.Clear;
        end else
          Sleep(100);
      end;
    end;
  except
    on e: EProcess do begin
      {$IFDEF Windows}
      FormatMessage(
        FORMAT_MESSAGE_ALLOCATE_BUFFER or FORMAT_MESSAGE_FROM_SYSTEM,
        nil,GetLastError,MAKELANGID(LANG_NEUTRAL,SUBLANG_DEFAULT),
        @ErrMsg,0,nil
      );
      {$ELSE}
      ;
      {$ENDIF}
      WriteLn(ErrMsg);
      Exit;
    end;
  on e: Exception do begin
      MessageDlg('Error',e.Message,mtError,[mbOK],0);
      Exit;
    end;
  end;
  repeat
    n:=CmdProcess.Output.Read(MemStr.Memory^,READ_BYTES);
    if n>0 then begin
      StrList.LoadFromStream(MemStr);
      WriteLn(StrList.Text);
    end;
  until n<=0;
  StrList.Free;
  MemStr.Free;
  CmdProcess.Free;
end;

And what is the question ?

Michael.

See processdemo example:
http://wiki.lazarus.freepascal.org/Executing_External_Programs#Using_input_and_output_of_a_TProcess

Vincent

@michael:
Reading part by part doesn't work, I got junks instead.

@vincent:
Thanks, I don't know if the page has been extended. I'll see if it fits my need.