TProcess input
lazarus / 32-Linux

----------------------------------------------------------------------
HomeBoy38 · 2022-12-23 09:51

Hi,

I am trying to interface a command line program (so no console shown)
but I am stuck on the input part.

Here is the simplified version of my code:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TMainForm.BCONClick(Sender: TObject);var AStringList:
TStringList; MyOutput: String; CMD: TProcess;begin CMD :=
TProcess.Create(nil); CMD.Options := [poUsePipes, poStderrToOutPut,
poWaitOnExit]; CMD.Executable := 'myexe'; CMD.Parameters.Clear; CMD.Pa
rameters.Add('param1'); CMD.Parameters.Add('param2'); MyOutput :=
'yes' + #10; CMD.Execute; CMD.Input.Write(MyOutput,
Length(MyOutput)); AStringList := TStringList.Create; MyOutput := ''; 
sleep(100); Application.ProcessMessages; AStringList.LoadFromStream(CM
D.Output); MyOutput := AStringList.Strings[AStringList.Count - 1]; if
Copy(MyOutput, 1, 3) = 'err' then 
ShowMessage('error'); CMD.Free; AStringList.Free;end; 
While running, 'myexe' can ask for one or more 'yes' to continue, so
far, I am trying to input at least the first one.
If an error occurs, I am correctly exiting the 'myexe' and the error
message is shown (if everything goes fine, nothing to do).
I really do not understand how to catch the 'Type yes' message from
'myexe', but even more, I do not understand why blindly writing to the
input does not work?

Thanks in advance

----------------------------------------------------------------------
marcov · 2022-12-23 11:22

Have a look at  https://stackoverflow.com/questions/72335247/input-
and-output-pipe-in-lazarus-tprocess

and the ZIP that I posted there.  Note that it is best to first test
with some simple FPC programs before testing your final target, just
in case that program somehow behaves atypically.

Note that your code says to wait on exit (Powaitonexit), and only then
sends input.

----------------------------------------------------------------------
Edson · 2022-12-23 15:49

To interact with a process I recommend to use my library:
https://github.com/t-edson/UnTerminal

It's completely driven by events and have prompt detection so you can
answer any question the program ask.

----------------------------------------------------------------------
HomeBoy38 · 2022-12-26 08:26

Hi,
First thanks to both of you for your answers.
If I understand correctly, I cannot use TProcess natively to do what I
need without wrapping TProcess.

I will make a try on your advices.
During my researches, I have found your codes, once appeared a bit
complex for my simple search, and the other one was talking about
Minecraft server so I wrongly thought I was leaving my path.

Thanks.

----------------------------------------------------------------------
Hartmut · 2022-12-26 11:19

For 'TProcess' with redirected input and output I use this code. Works
on Windows and Linux.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
exec_TProcess_InOut(cmd: ansistring; SLK,SLI: TStringList;           
                 var SLO: TStringList; var ec,es: longint);   {calls
an external program 'cmd' via 'TProcess' and redirects Input from   
StringList 'SLI' and redirects Output into StringList 'SLO'. Waits
until    the external program has finished.     - 'SLK' = commandline
parameters.     - 'ec' and 'es' are error codes.     - 'SLO': must be
initialized external}   var PZ: TProcess;       s: ansistring;     
 n,i: longint;   begin   ec:=-1; es:=-1; {unspecific error codes, e.g.
if 'cmd' not found}   PZ:=TProcess.Create(nil);    try     try     
 PZ.Executable:=cmd;       PZ.Parameters:=SLK;     
 PZ.Options:=[poUsePipes];       PZ.Execute;        n:=SLI.Count;    
 for i:=0 to n-1 do          begin          s:=SLI.Strings[i] +
LineEnding;           PZ.Input.Write(s[1],length(s));          end;  
    while PZ.Running do {wait until external program has finished}   
     sleep(50);        SLO.LoadFromStream(PZ.Output);      finally   
  ec:=PZ.ExitCode;       es:=PZ.ExitStatus;       PZ.Free;     end;
{try2}    except     on E:Exception do        begin        if ec=0
then ec:=-1;        if es=0 then es:=-1;        end;   end; {try1} 
 end; procedure Test_TProcess_InOut;   {Demo for
exec_TProcess_InOut()}   var SLK,SLI,SLO: TStringList;       cmd:
ansistring;       ec,es: longint;   begin   cmd:='my.exe'; 
 SLK:=TStringList.Create; {commandline parameters: }     
SLK.Add('param1');      SLK.Add('param2');   SLI:=TStringList.Create;
{create Input-StringList}      SLI.Add('username');     
SLI.Add('password');      SLI.Add('y');   SLO:=TStringList.Create;
{create Output-StringList}    exec_TProcess_InOut(cmd,SLK,SLI,SLO,
ec,es);   SLK.Free;   SLI.Free;   SLO.Free;    if (ec<>0) or (es<>0)
then writeln('ERROR: ec=', ec, ' es=', es);   end;
HTP

----------------------------------------------------------------------
HomeBoy38 · 2022-12-26 18:27

@marcov: I was not able to input to myexe using your sample code, I
did not figure out why and I quit
@Edson: this is too complex for my need by I am sure it will help
someone else
@Hartmut: your code is very similar to my tests before I post my
question, but yours works 

Thanks for your contribution, on my side, it appears to be closed, but
if anyone else needs, you can use my topic

Have a great end of year