[SOLVED} Issue with TProcess and top
lazarus / 32-Linux

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Barry55 · 2021-01-23 17:35

I am trying to use TProcess to get some information about what is
happening on my Raspberry pi. Some of it is working fine. the
following code is OK

Var
  AProcess        : TProcess;
  AStringList     : TStringList;
  ResultStr        : String;

Begin
  AStringList := TStringList.Create;
  AProcess := TProcess.Create(nil);
  ResultStr := '';

  Try
    AProcess.Executable := 'vcgencmd';
    Aprocess.Parameters.Add('measure_temp');
    AProcess.Options := [poWaitOnExit, poUsePipes];
    AProcess.Execute;

    AStringList.LoadFromStream(AProcess.Output);
    ResultStr := AStringList.Text;
  finally
    AStringList.Free;
    AProcess.Free;
  end;

and I get the information I expected in ResultStr. However if I try
the following

  AStringList := TStringList.Create;
   AProcess := TProcess.Create(nil);
   ResultStr := '';

   Try
     AProcess.Executable := '/usr/bin/top';
     Aprocess.Parameters.Add('-n 1 -p0');
     AProcess.Options := [poWaitOnExit, poUsePipes];
     AProcess.Execute;

     AStringList.LoadFromStream(AProcess.Output);
     ResultStr := AStringList.Text;
   finally
     AStringList.Free;
     AProcess.Free;
   end;

ResultStr is always empty. I assume it might be something to do with
top clearing the screen before it starts but I am not sure how to get
round this and wondered if anyone had any ideas.

Many thanks

Regards

Barry

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Barry55 · 2021-01-23 18:09

Sorry - went back to the documentation and found the issue, I needed
to do this to make it work

   AStringList := TStringList.Create;
   AProcess := TProcess.Create(nil);
   ResultStr := '';

   Try
     AProcess.Executable := '/usr/bin/top';
     Aprocess.Parameters.Add('-n1');
     Aprocess.Parameters.Add('-p0');;
     Aprocess.Parameters.Add('-b');
     AProcess.Options := [poWaitOnExit, poUsePipes];
     AProcess.Execute;

     AStringList.LoadFromStream(AProcess.Output);
     ResultStr := AStringList.Text;
   finally
     AStringList.Free;
     AProcess.Free;
   end;

Barry

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PascalDragon · 2021-01-24 11:05

In the future please use code tags. This results in better readability
here on the forum and avoids the forum software potentially messing up
code.