This will return a list of running process ids, names and their command lines on Windows XP and above. For Windows 2000 and lower you will need to find a workaround.

use Win32::OLE;

my $wmi = Win32::OLE->GetObject("winmgmts:") 
or die "wmi connect failed!";

my $P = $wmi->ExecQuery("SELECT * FROM Win32_Process")
or die "Win32_Process connect failed!";
        
foreach my $p (in $P) {
    print join(',' , $p->ProcessId, $p->Name, $p->CommandLine)."\n";
}
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For more info on WMI and Win32_Process see Microsoft's documentaion