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James Macfarlane


Parse::Win32Registry - Parse Windows Registry Files


    use strict;
    use Parse::Win32Registry qw(:REG_);

    my $filename = shift or die "Filename?";

    my $registry = Parse::Win32Registry->new($filename);
    my $root_key = $registry->get_root_key;

    # The following code works on USER.DAT or NTUSER.DAT files

    my $software_key = $root_key->get_subkey(".DEFAULT\\Software")
                    || $root_key->get_subkey("Software");

    if (defined($software_key)) {
        my @user_key_names = (
            "Microsoft\\Windows\\CurrentVersion\\Explorer\\Shell Folders",
            "Microsoft\\Internet Explorer",
            "Microsoft\\Internet Explorer\\Main",

        print_list_of_keys($software_key, @user_key_names);

        # This demonstrates how to use the decode function from the
        # Encode module to convert binary data into a Unicode string.
        # Encode has been in the Perl standard library since 5.8.
        use Encode;
        foreach my $version (qw(8.0 9.0 10.0 11.0)) {
            my $key_name = "Microsoft\\Office\\$version\\Common\\UserInfo";
            if (my $userinfo_key = $software_key->get_subkey($key_name)) {
                print "\n", $userinfo_key->as_string, "\n";
                foreach my $value_name ("UserName", "UserInitials", "Company") {
                    if (my $value = $userinfo_key->get_value($value_name)) {
                        print $value->as_string, "\n";
                        my $data = decode("UCS-2LE", $value->get_data);
                        print "$value_name is the unicode string '$data'\n";

    # The following code works on SYSTEM.DAT or SOFTWARE files

    my $software_key = $root_key->get_subkey("Software") || $root_key;

    if (defined($software_key)) {
        my @software_key_names = (
            "Microsoft\\Windows NT\\CurrentVersion",
            "Microsoft\\Internet Explorer",

        print_list_of_keys($software_key, @software_key_names);

        # This demonstrates how you can deal with a Unix date
        # found in a registry value
        my $key_name = "Microsoft\\Windows NT\\CurrentVersion";
        if (my $currentversion_key = $software_key->get_subkey($key_name)) {
            print "\n", $currentversion_key->as_string, "\n";
            if (my $value = $currentversion_key->get_value("InstallDate")) {
                print $value->as_string, "\n";
                my $data = $value->get_data;
                print "InstallDate was ", scalar gmtime $data, " GMT\n";
                print "InstallDate was ", scalar localtime $data, " Local\n";

    # The following code works on SYSTEM.DAT or SYSTEM files

    my $system_key = $root_key->get_subkey("System") || $root_key;

    my $ccs_name = "CurrentControlSet"; # default for Win95
    if (my $key = $system_key->get_subkey("Select")) {
        my $current_value = $key->get_value("Current");
        $ccs_name = "ControlSet00" . $current_value->get_data;
        print "CurrentControlSet = $ccs_name\n";

    my $ccs_key = $system_key->get_subkey($ccs_name);

    if (defined($ccs_key)) {
        my @system_key_names = (

        print_list_of_keys($ccs_key, @system_key_names);

    # Given a starting key object and a list of subkey names
    # relative to the starting key, this function will print
    # out each subkey and its values
    sub print_list_of_keys {
        my ($start_key, @key_names) = @_;
        foreach my $key_name (@key_names) {
            if (my $key = $start_key->get_subkey($key_name)) {
                print "\n", $key->as_string, "\n";
                foreach my $value ($key->get_list_of_values) {
                    print $value->as_string, "\n";


Parse::Win32Registry is a module for parsing Windows Registry files, allowing you to read the keys and values of a registry file without going through the Windows API.

It provides an object-oriented interface to the keys and values in a registry file. Registry files are structured as trees of keys, with each key containing further subkeys or values.

The module is intended to be cross-platform, and run on those platforms where Perl will run.

It supports both Windows NT registry files (Windows NT, 2000, XP, 2003) and Windows 95 registry files (Windows 95, 98, and Millennium Edition).


Start by creating a Registry object from a valid registry file. Use the Registry object's get_root_key method to obtain the root key of that registry file. This root key is your first Key object. From this key, you can explore the Key and Value objects that comprise the registry file using the methods described below.

Data is read directly from a registry file when a Key or Value object is created, and discarded when the Key or Value object is destroyed. This avoids any delay in parsing an entire registry file before any Key or Value object is instantiated as it is anticipated that generally code will only be extracting a subset of the keys and values contained in a registry file.

Registry Object Methods

$registry = Parse::Win32Registry->new( 'filename' );

Creates a new Registry object for the specified registry file.

$root_key = $registry->get_root_key;

Returns the root Key object of the registry file.

The root key of a registry file is not the same as one of the virtual roots of the registry (HKEY_LOCAL_MACHINE, HKEY_USERS, etc) that you may be familiar with from using tools such as REGEDIT.

Key Object Methods


Returns the name of the key. The root key of a Windows 95 based registry file does not have a name; this is returned as an empty string.


Returns the path to the key. This is relative to the root key of the registry file, not a virtual root such as HKEY_LOCAL_MACHINE.

$key->get_subkey( 'key name' )

Returns a Key object for the specified subkey name. If a key with that name does not exist, nothing will be returned.

You can specify a path to a subkey by separating keys using the path separator '\\'. For example:

    $key->get_subkey( 'Software\\Microsoft\\Windows' )

A path is always relative to the current key. If any key in the path does not exist, nothing will be returned.

$key->get_value( 'value name' )

Returns a Value object for the specified value name. If a value with that name does not exist, nothing will be returned.


Returns a list of Key objects representing the subkeys of the current key. If a key has no subkeys, an empty list will be returned.


Returns a list of Value objects representing the values of the current key. If a key has no values, an empty list will be returned.


Returns the timestamp for the key as a time value (the number of seconds since your computer's epoch) suitable for passing to gmtime or localtime.

Only Windows NT registry keys have a timestamp.

Returns nothing if the date is out of range or if called on a Windows 95 registry key.


Returns the timestamp as a ISO 8601 string, for example, '2010-05-30T13:57:11Z'. The Z indicates that the time is GMT ('Zero Meridian').

Returns the string '(undefined)' if the date is out of range or if called on a Windows 95 registry key.


Returns the path of the key as a string. The timestamp will be appended for Windows NT registry keys.


Prints $key->as_string to standard output.

Value Object Methods


Returns the name of the value. In both Windows NT and Windows 95 based registry files you can get values without a name. This is returned as an empty string.


Returns the integer representing the type of the data. The constants for the value types can be imported from the Parse::Win32Registry module with

    use Parse::Win32Registry qw( :REG_ );

Returns the type of the data as a string instead of an integer constant, making it more suitable for printed output.


Returns the data for the value.

REG_SZ, REG_EXPAND_SZ, and REG_MULTI_SZ values will be returned as strings. The string data will be converted from Unicode (UCS-2LE) for Windows NT based registry files. Any terminating null characters will be removed from REG_SZ and REG_EXPAND_SZ values. To extract the component strings of a REG_MULTI_SZ value, you will need to use the built-in split function to separate on null characters.

REG_DWORD values are unpacked and returned as unsigned integers. undef will be returned for REG_DWORD values that contain invalid data.

All other types are returned as packed binary strings.


Returns the data for a value, making it safe for printed output.

REG_SZ and REG_EXPAND_SZ values will be returned directly from get_data, REG_MULTI_SZ values will have their component strings prefixed by indices to more clearly show the number of elements, and REG_DWORD values will be returned as a hexadecimal number followed by its parenthesized decimal equivalent. All other types of values will be returned as a string of hex octets.

'(invalid data)' will be returned for REG_DWORD values that contain invalid data, instead of the undef returned by get_data.

'(no data)' will be returned if get_data returns an empty string.


Returns the name, type, and data for the value as a string, safe for printed output.

'(Default)' will be displayed for those values that do not have names.


Prints $value->as_string to standard output.



On request, Parse::Win32Registry will export the registry type constants:

    use Parse::Win32Registry qw( :REG_ );

The :REG_ tag exports all of the following constants:


Support Functions

Parse::Win32Registry will export the following support functions on request:

convert_filetime_to_epoch_time( $packed_filetime )

Returns the epoch time for the given Win32 FILETIME. A Win32 FILETIME is a 64-bit integer containing the number of 100-nanosecond intervals since January 1st, 1601 and can sometimes be found in Windows NT registry values. It should be passed as 8 bytes of packed binary data.

undef will be returned if the date is earlier than your computer's epoch. The epoch begins at January 1st, 1970 on Unix and Windows machines.

iso8601( $epoch_time )

Returns the ISO8601 string for the given $epoch_time, for example, '2010-05-30T13:57:11Z'.

The string '(undefined)' will be returned if the epoch time is out of range.

For example, if 'UpdateTime' is a REG_BINARY value that contains a Win32 FILETIME, you can extract and convert it as follows:

    use Parse::Win32Registry qw( convert_filetime_to_epoch_time iso8601 );

    if (my $value = $key->get_value('UpdateTime')) {
        my $data = $value->get_data;
        my $update_time = convert_filetime_to_epoch_time($data);
        my $update_time_as_string = iso8601($update_time);
        print "UpdateTime = $update_time_as_string\n";



regdump.pl is used to display the keys and values of a registry file. You can use this to help develop your own scripts, or as a command line tool for examining registry files.

Type regdump.pl on its own to see the help:

    regdump.pl <filename> [subkey] [-r] [-q]
        -r or --recurse     traverse all child keys from the root key
                            or the subkey specified
        -q or --quiet       do not display values

The contents of the root key will be displayed unless a subkey is specified. Paths to subkeys are always specified relative to the root key. By default, only the subkeys and values immediately underneath the specified key will be displayed. To display all keys and values beneath a key, use the -r or --recurse option.

For example, regdump.pl ntuser.dat might display the following:

    $$$PROTO.HIV  [2005-01-01T09:00:00Z]
    ..\Control Panel
    ..\Keyboard Layout
    ..\UNICODE Program Groups

From here, you can explore the subkeys to find those keys or values you are interested in:

    regdump.pl ntuser.dat software
    regdump.pl ntuser.dat software\microsoft
    regdump.pl ntuser.dat software\microsoft\windows
    regdump.pl ntuser.dat software\microsoft\windows\currentversion

Remember to quote any subkey path that contains spaces:

    regdump.pl ntuser.dat "software\microsoft\windows nt\currentversion"


regfind.pl is used to search the keys, values, or data of a registry file for a matching string.

Type regfind.pl on its own to see the help:

    regfind.pl <filename> <search-string> [-k] [-v] [-d]
        -k or --key       search key names for a match
        -v or --value     search value names for a match
        -d or --data      search value data for a match

To search for the string "recent" in the names of any keys or values:

    regfind.pl ntuser.dat recent -kv

To search for the string "administrator" in the data of any values:

    regfind.pl ntuser.dat administrator -d

Search strings are not case-sensitive.


regdiff.pl is used to compare two registry files and identify the differences between them.

Type regdiff.pl on its own to see the help:

    regdiff.pl <filename1> <filename2> [subkey] [-p] [-q]
        -p or --previous    show the previous key or value
                            (this is not normally shown)
        -q or --quiet       do not display values

When comparing Windows NT based registry files, regdiff.pl can identify if a key has been updated by comparing timestamps. When comparing Windows 95 based registry files, it needs to check all its values to see if any have changed.

You can limit the comparison by specifying an initial subkey.


If you run into problems parsing a registry file, the error message will probably begin with 'Could not read...' or 'Invalid...'. Troubleshooting these messages is possible, but you will need to be comfortable dealing with binary data and be prepared to refer to the source for information on the internal registry data structures.

'Could not read...' indicates that the code tried to read data that did not exist; this is typically because the offset to that data was invalid. To identify the source of the incorrect offset, you need to work down through the registry tree, key by key, until you reach the key or value that generates the error. Suspect the preceding key of holding invalid data.

'Invalid...' indicates that the data was read successfully, but one of the checks failed. This will occur either because the offset to that data was invalid and points to the wrong place in the registry file (which can be troubleshot as for 'Could not read...'), or because the data being parsed is a new type of data structure. Unfortunately there is no easy way to distinguish these without becoming familiar with internal registry data structures. If you do think it is a new type of data structure, let the author know.

The debugging_info method can be used in place of the as_string method to display additional information about keys and values. This method has not been documented as it is not considered a stable part of the public interface, and its output is largely unintelligible to the unfamiliar. You may, however, find it useful.


This would not have been possible without the work of those people who have analysed and documented the structure of Windows Registry files, namely: the WINE Project (see misc/registry.c in older releases), the Samba Project (see utils/editreg.c and utils/profiles.c), the oft-referenced B.D. (for WinReg.txt), and Petter Nordahl-Hagen (see chntpw's ntreg.h).


James Macfarlane, <jmacfarla@cpan.org>

If you have any requests or contributions, contact me.


Copyright (C) 2006,2007 by James Macfarlane

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