How do I communicate with a Windows process?

[IOl01]

My goal is to capture the output of netstat and getmac without flashing up a command window every time I call them (this is on Windows 7).

The stripped down code I have so far (place in sandbox.pl):

use strict;
use warnings;
use Win32::Process;
use Win32;
use Data::Dumper;

my $netstat_obj;
my $create_status = Win32::Process::Create(
        $netstat_obj,
        'C:/Windows/System32/netstat.exe', 'netstat -a -e -n -o -s -r'
+,
        0, DETACHED_PROCESS | CREATE_NO_WINDOW | CREATE_SUSPENDED,
        'C:/temp/' ) || die Win32::FormatMessage(Win32::GetLastError()
+);

print Data::Dumper->new(['1', $create_status, $netstat_obj], ['where__
+________', 'create_status', 'netstat_obj'])->Indent(1)->Sortkeys(1)->
+Useqq(1)->Deparse(1)->Dump();

my $NETSTAT_FH;
my $open_status = Win32::Process::Open(
        $NETSTAT_FH,
        $netstat_obj->GetProcessID(),
        0 ) || die Win32::FormatMessage(Win32::GetLastError());

print Data::Dumper->new(['2', $open_status, $NETSTAT_FH], ['where_____
+_____', 'open_status', 'NETSTAT_FH'])->Indent(1)->Sortkeys(1)->Useqq(
+1)->Deparse(1)->Dump();

$netstat_obj->Resume();
my $netstat_data = '';
{
  my $offset = 0;
  my $length = 1024;
  my $buffer = undef;
  while(my $bytes_read = $NETSTAT_FH->sysread($buffer, $length, $offse
+t)) {
    if(defined $bytes_read) {
      $netstat_data .= $buffer;
      $buffer = undef;
      last if($bytes_read == 0);
      $offset += $bytes_read;
    }
    else { die "ERROR: Could not read from NETSTAT_FH: $!  "; }
  }
}
$netstat_obj->Wait(2000);
my $netstat_exit;
$netstat_obj->GetExitCode($netstat_exit);

print Data::Dumper->new(['3', $netstat_obj, $NETSTAT_FH, $netstat_data
+], ['where__________', 'netstat_obj', 'NETSTAT_FH', 'netstat_data'])-
+>Indent(1)->Sortkeys(1)->Useqq(1)->Deparse(1)->Dump();

The results of running the above code:

C:\temp>perl.exe sandbox.pl
$where__________ = 1;
$create_status = 1;
$netstat_obj = bless( do{\(my $o = 1776208)}, 'Win32::Process' );
$where__________ = 2;
$open_status = 1;
$NETSTAT_FH = bless( do{\(my $o = 1777552)}, 'Win32::Process' );
Your vendor has not defined Win32::Process macro sysread, used at sand
+box.pl line 32. (Error was: 'Invalid argument')
at C:/xampp/perl/site/lib/Win32/Process.pm line 53.

What I am trying to do in the above code is:

1. create a new (detached and suspended) Windows process sans command window
2. open a filehandle to the newly created process for reading said process's STDOUT
3. read all of the data from the filehandle
4. and wait for netstat to exit, then find its exit code

As the above output demonstrates, I am stuck on #3 (and despite the CREATE_NO_WINDOW constant, a window is  still  being created :-/ ).

In place of the sysread, I have tried: read, getlines, and getline; all with the same error "Your vendor has not defined Win32::Process macro X, used at …", where X is one of the aforementioned methods.

So my question has a few parts:

• How do you create a Windows process without a window?
• How do you attach a filehandle to said process's STDOUT?
• How do you read from said filehandle?

Thank-you for your thoughts and suggestions,
IOl01

[BrowserUk]

Try:

my @info = qx[ start /b /wait netstat -a -e -n -o -s -r ];;
print for @info;;

Or is that too easy?

[IOl01]

Thanks, your result is exactly what I was looking for!   :-D
I was complicating my code way too much…   :-/

Is it safe to say "Stay away from the Win32:: namespace!" is a good idea?

[BrowserUk]

Is it safe to say "Stay away from the Win32:: namespace!" is a good idea?

Hell no! There are lots of not just useful, but in many cases little-alternative-to, modules in there.

It just pays to look for the simplest solution first.

BTW: Does this also work for you? (If not, why not?):

my @info = qx[ netstat -a -e -n -o -s -r ];;
print for @info;;

[morgon]

How do you create a Windows process without a window?

If you are using ActiveState (I don't know about Strawberry), then there is a "wperl.exe" that you can use (i.e. you start your script with "wperl script.pl"). This is just a normal Perl-interpreter but does not start a new command-window.

[AnomalousMonk]

Strawberry has wperl.exe as well. Same purpose.

[furry_marmot]

Have you tried

open NETSTAT, "netstat -a -e -n -o -s -r|" or die "Couldn't open netst
+at for parsing: $!";
@lines = <NETSTAT>;
#Parse as you like

There are reasons to use Win32::Process to control a process. And there are reasons not to. This might be one of the latter.

--marmot

[ahmad]

netstat is a windows command, you can use it from the command line, so you just have to use back ticks and it will work without a cmd window or anything else

my $cmd = `netstat -a -e -n -o -s -r`;
print $cmd;

You might want to use the full path for the netstat command.