How can I capture output from the Windows cmd shell?

Question

Is there any way with, say Perl or PHP, that I can grab output from another process that outputs to the Windows cmd shell? I have a game server that outputs certain information, for example say 'player finished track in 43s' and I want to grab that line and use Perl or PHP to send a request to a webserver to update ranks on a web page. Is there a way to grab that output pipe in Perl or PHP? Or could I achieve this using C++ Windows API maybe?

Let me clarify here: I want to execute a seperate Perl or PHP script that grabs output from the Windows cmd shell, and the output that is being displayed to the Windows cmd shell is coming from a different process.

Answer 1

Capturing the output in Perl is as simple as:

$output = qx(command);

or

$output = `command`;  # backticks

Refer: perldoc perlop

Answer 2

You could use IPC::Open3 to read from the other process' standard output. Note that inter-process communication assumes a parent/child relationship between the processes. If that's not the case... I'm not aware of a mechanism for attaching to the output of a pre-existing process. In that case you may need to alter the producer to write data to a log file (or database) that your application can read from.

Answer 3

If all you care about is STDOUT, you can just use open2 from IPC::Open2:

#!/usr/bin/perl

use strict;
use warnings;

use IPC::Open2;

#if there are arguments pretend to be the server
#for this example
if (@ARGV) {
    local $| = 1;
    for my $i (1 .. 100) {
     print "pid $$ iter $i\n";
     sleep 1;
    }
    exit;
}        

#run perl with the current script as its argument,
#pass in an arg so that we trigger the behaviour 
#above
open2 my $out, my $in, $^X, $0, 1 
    or die "could not run '$^X $0 1': $!\n";

while (<$out>) {
    s/[\r\n]//g;
    print "pid $$ saw [$_]\n";
}

Answer 4

This code redirects the STDOUT of a console application to a stringlist, which you can use on a memo for example. It's Delphi code, but in C++ the basic idea is exactly the same.

I use it to run console applications hidden, while redirecting the output to my own application, to show in a pane. It adds a new line to AStrings as soon as data comes in, so you'll have access to the output of the other application before it finishes.

procedure RunConsoleApp(const CommandLine: string; AStrings: TStrings);
type
  TCharBuffer = array[0..MaxInt div SizeOf(Char) - 1] of Char;
const
  MaxBufSize = 1024;
var
  I: Longword;
  SI: TStartupInfo;
  PI: TProcessInformation;
  SA: PSecurityAttributes;
  SD: PSECURITY_DESCRIPTOR;
  NewStdIn: THandle;
  NewStdOut: THandle;
  ReadStdOut: THandle;
  WriteStdIn: THandle;
  Buffer: ^TCharBuffer;
  BufferSize: Cardinal;
  Last: WideString;
  Str: WideString;
  ExitCode_: DWORD;
  Bread: DWORD;
  Avail: DWORD;
begin
  GetMem(SA, SizeOf(TSecurityAttributes));

  case Win32Platform of
    VER_PLATFORM_WIN32_NT:
      begin
        GetMem(SD, SizeOf(SECURITY_DESCRIPTOR));
        SysUtils.Win32Check(InitializeSecurityDescriptor(SD, SECURITY_DESCRIPTOR_REVISION));
        SysUtils.Win32Check(SetSecurityDescriptorDacl(SD, True, nil, False));
        SA.lpSecurityDescriptor := SD;
      end; {end VER_PLATFORM_WIN32_NT}
  else
    SA.lpSecurityDescriptor := nil;
  end; {end case}

  SA.nLength := SizeOf(SECURITY_ATTRIBUTES);
  SA.bInheritHandle := True;

  SysUtils.Win32Check(CreatePipe(NewStdIn, WriteStdIn, SA, 0));

  if not CreatePipe(ReadStdOut, NewStdOut, SA, 0) then
  begin
    CloseHandle(NewStdIn);
    CloseHandle(WriteStdIn);
    SysUtils.RaiseLastWin32Error;
  end; {end if}

  GetStartupInfo(SI);
  SI.dwFlags := STARTF_USESTDHANDLES or STARTF_USESHOWWINDOW;
  SI.wShowWindow := {SW_SHOWNORMAL} SW_HIDE;
  SI.hStdOutput := NewStdOut;
  SI.hStdError := NewStdOut;
  SI.hStdInput := NewStdIn;

  if not CreateProcess(nil, PChar(CommandLine), nil, nil, True, CREATE_NEW_CONSOLE, nil, nil, SI, PI) then
  begin
    CloseHandle(NewStdIn);
    CloseHandle(NewStdOut);
    CloseHandle(ReadStdOut);
    CloseHandle(WriteStdIn);
    SysUtils.RaiseLastWin32Error;
  end; {end if}

  Last := '';
  BufferSize := MaxBufSize;
  Buffer := AllocMem(BufferSize);

  try
    repeat
      SysUtils.Win32Check(GetExitCodeProcess(PI.hProcess, ExitCode_));
      PeekNamedPipe(ReadStdOut, Buffer, BufferSize, @Bread, @Avail, nil);

      if (Bread <> 0) then
      begin
        if (BufferSize < Avail) then
        begin
          BufferSize := Avail;
          ReallocMem(Buffer, BufferSize);
        end; {end if}
        FillChar(Buffer^, BufferSize, #0);
        Windows.ReadFile(ReadStdOut, Buffer^, BufferSize, Bread, nil);
        Str := Last;
        I := 0;

        while (I < Bread) do
        begin

          case Buffer^[I] of
            #0: inc(I);
            #7: begin
                  inc(I);
                  Windows.Beep(800, 50);
                  Str := Str + '^';
                end;
            #10:
              begin
                inc(I);
                AStrings.Add(Str);
                Str := '';
              end; {end #10}
            #13:
              begin
                inc(I);
                if (I < Bread) and (Buffer^[I] = #10) then
                  inc(I);
                AStrings.Add(Str);
                Str := '';
              end; {end #13}
          else
            begin
              Str := Str + Buffer^[I];
              inc(I);
            end; {end else}
          end; {end case}
        end; {end while}
        Last := Str;
      end; {end if}
      Sleep(1);
      Application.ProcessMessages;

    until (ExitCode_ <> STILL_ACTIVE);

    if Last <> '' then
      AStrings.Add(Last);

  finally
    FreeMem(Buffer);
  end; {end try/finally}

  CloseHandle(PI.hThread);
  CloseHandle(PI.hProcess);
  CloseHandle(NewStdIn);
  CloseHandle(NewStdOut);
  CloseHandle(ReadStdOut);
  CloseHandle(WriteStdIn);

end; {end procedure}

Answer 5

You need to start your server within Perl:

my $server_out = `server.exe`; # Note the backticks.

Now $server_out contains the output of server.exe. But the trick here is that you have to wait until server.exe exits to get the out put.

Try IPC::Run (which is not a core module)

use English;
use IPC::Run;
my ($stdout, $stderr);

IPC::Run::run([$cmd, $arg1, $arg2, $argN], \undef, \$stdout, $stderr);

while(<$stdout>) {
  print "Cmd said $_\n";
}

Note: Code not tested.

Found the info here.