Win32::Process::Info - Provide process information for Windows 32 systems.


 use Win32::Process::Info
 $pi = Win32::Process::Info->new ([machine], [variant]);
 $pi->Set (elapsed_as_seconds => 0);    # In clunks, not seconds.
 @pids = $pi->ListPids ();      # Get all known PIDs
 @info = $pi->GetProcInfo ();   # Get the max


This package covers a multitude of sins - as many as Microsoft has invented ways to get process info and I have resources and gumption to code. The key to this mess is the 'variant' argument to the 'new' method (q.v.).


The main purpose of the Win32::Process::Info package is to get whatever information is convenient (for the author!) about one or more Windows 32 processes. GetProcInfo (which see) is therefore the most-important subroutine in the package. See it for more information.

Unless explicitly stated otherwise, modules, variables, and so on are considered private. That is, the author reserves the right to make arbitrary changes in the way they work, without telling anyone. For subroutines, variables, and so on which are considered public, the author will make an effort keep them stable, and failing that to call attention to changes.

The following methods should be considered public:

$pi = Win32::Process::Info->new ([machine], [variant], [hash])

This method instantiates a process information object, connected to the given machine, and using the given variant.

The following variants are currently supported:

NT - Uses the NT-native mechanism. Good on any NT, including Windows 2000. This variant does not support connecting to another machine, so the 'machine' argument must be an empty string (or undef, if you prefer).

WMI - Uses the Windows Management Implementation. Good on Win2K, ME, and possibly others, depending on their vintage and whether WMI has been retrofitted.

The initial default variant comes from environment variable PERL_WIN32_PROCESS_INFO_VARIANT. If this is not found, it will be 'WMI,NT', which means to try WMI first, and NT if WMI fails. This can be changed using Win32::Process::Info->Set (variant => whatever).

The hash argument is a hash reference to additional arguments, if any. The hash reference can actually appear anywhere in the argument list, though positional arguments are illegal after the hash reference.

The following hash keys are supported:

  variant => corresponds to the 'variant' argument (all)
  host => corresponds to the 'machine' argument (WMI)
  user => username to perform operation under (WMI)
  password => password corresponding to the given username (WMI)

ALL hash keys are optional. SOME hash keys are only supported under certain variants. These are indicated in parentheses after the description of the key. An attempt to specify a key on a variant that does not support it is an error.

@values = $pi->Get (attributes ...)

This method returns the values of the listed attributes. If called in scalar context, it returns the value of the first attribute specified, or undef if none was. An exception is raised if you specify a non-existent attribute.

This method can also be called as a class method (that is, as Win32::Process::Info->Get ()) to return default attributes values.

The relevant attribute names are:

elapsed_as_seconds is TRUE to convert elapsed user and kernel times to seconds. If FALSE, they are returned in clunks (that is, hundreds of nanoseconds). The default is TRUE.

variant is the variant of the process info code in use, and should be zero or more of 'WMI' or 'NT', separated by commas. 'WMI' selects the Windows Management Implementation, and 'NT' selects the Windows NT native interface. variant can only be set on the class, not the instance. If you set variant to an empty string (the default), the next "new" will iterate over all possibilities, and set variant to the first one that actually works.

machine is the name of the machine connected to. This is not available as a class attribute.

@values = $pi->Set (attribute => value ...)

This method sets the values of the listed attributes, returning the values of all attributes listed if called in list context, or of the first attribute listed if called in scalar context.

This method can also be called as a class method (that is, as Win32::Process::Info->Set ()) to change default attribute values.

The relevant attribute names are the same as for Get. However:

elapsed_as_seconds is TRUE to convert elapsed user and kernel times to seconds. If FALSE, they are returned in clunks (that is, hundreds of nanoseconds). The default is TRUE.

variant is read-only at the instance level. That is, Win32::Process::Info->Set (variant => 'NT') is OK, but $pi->Set (variant => 'NT') will raise an exception.

machine is not available as a class attribute, and is read-only as an instance attribute. It is not useful for discovering your machine name - if you instantiated the object without specifying a machine name, you will get nothing useful back.

@pids = $pi->ListPids ();

This method lists all known process IDs in the system. If called in scalar context, it returns a reference to the list of PIDs. If you pass in a list of pids, the return will be the intersection of the argument list and the actual PIDs in the system.

@info = $pi->GetProcInfo ();

This method returns a list of anonymous hashes, each containing information on one process. If no arguments are passed, the list represents all processes in the system. You can pass a list of process IDs, and get out a list of the attributes of all such processes that actually exist. If you call this method in scalar context, you get a reference to the list.

What keys are available depends on the variant in use. You can hope to get at least the following keys for a "normal" process (i.e. not the idle process, which is PID 0, nor the system, which is some small indeterminate PID) to which you have access:

    Name (generally the name of the executable file)

You may find other keys available as well, depending on which operating system you're using, and which variant of Process::Info you're using.

This method just returns the version number of the Win32::Process::Info object.


It should be obvious that this library must run under some flavor of Windows.

This library uses the following libraries:

 Win32::API (if using the NT-native variant)
 Win32API::Registry (if using the NT-native variant)
 Win32::ODBC (if using the WMI variant)

As of ActivePerl 630, none of this uses any packages that are not included with ActivePerl. Your mileage may vary.


 0.010 Released as Win32::Process::Info
 0.011 Added Version method
       Fixed warning in when -w in effect. Fix provided by Judy
           Hawkins (of Pitney Bowes, according to her mailing address),
           and accepted with thanks.
 0.012 Use environment variable PERL_WIN32_PROCESS_INFO_VARIANT to
           specify the default variant list.
       Add a hash reference argument to new (); use this to specify
           username and password to the WMI variant.
       Turn on debug privilege in NT variant. This also resulted in
           dependency on Win32API::Registry.
       Return OwnerSid and Owner in NT variant.


This module would not exist without the following people:

Aldo Calpini, who gave us Win32::API.

Jenda Krynicky, whose "How2 create a PPM distribution" ( gave me a leg up on both PPM and tar distributions.

Dave Roth,, author of Win32 Perl Programming: Administrators Handbook, which is published by Macmillan Technical Publishing, ISBN 1-57870-215-1

Dan Sugalski, author of VMS::Process, where I got (for good or ill) the idea of just grabbing all the data I could find on a process and smashing it into a big hash.

The folks of Cygwin (, especially Christopher G. Faylor, author of

Judy Hawkins of Pitney Bowes, for providing testing and patches for NT 4.0 without WMI.


Thomas R. Wyant, III (


Copyright 2001, 2002 by E. I. DuPont de Nemours and Company, Inc. All rights reserved.

This module is free software; you can use it, redistribute it and/or modify it under the same terms as Perl itself.