[fpc-pascal] Writeln() behaves differently on Windows and Linux, why?

[Michael Van Canneyt]

On Thu, 9 Jul 2020, Bo Berglund via fpc-pascal wrote:

> On Thu, 9 Jul 2020 16:25:50 +0000, Alexander Grotewohl
> <alex at dcclost.com> wrote:
>
>> perhaps try 'reset' or 'stty sane' in the terminal before running your program?
>
> reset in PuTTY gives me a new resized empty screen, but works exactly
> the same afterwards.
>
>> are you using the crt or video units at all?
> Yes, see below.
>>
>> it sounds like your terminal has gotten fudged somehow
>>
>
> I am using crt in the lpr file just for the sake of being able to shut
> it down sensibly:
>
>  try
>    RemoteSrv.ClientPort := 23500; //Set port explicitly
>    Logger.StdLog('Starting remote server on port: ' +
> IntToStr(RemoteSrv.ClientPort));
>    Writeln('Starting remote server on port: ' +
> IntToStr(RemoteSrv.ClientPort));
>    RemoteSrv.StartServer;
>    Writeln('Server running, hit q to exit!');
>    repeat
>      ch := ReadKey;  <== NEEDS unit crt to read the keypress
>    until ch='q'; {q}
>    Writeln('Shutting down server');
>    Logger.StdLog('Shutting down server');
>    RemoteSrv.StopServer;
>  finally
>    RemoteSrv.Free;
>  end;
>  Writeln('Terminating program');
>
> The messages put out from this code are all left aligned.
> From then on the messages are stacked sideways but on a new line.
>
> So when the server (it is a TCP/IP socket server) gets a client call
> this is written in the console by the writeln() executed inside the
> handler as I showed in my start message.

Is this done in a thread ? Since you're using indy, I suppose so.

The crt unit is not thread safe. The implementation on Windows and Linux is
totally different, which may explain the difference you see.

Michael.