11.7 HKCU
We all like to customize our environments.
We do it at home, at work, in our cars, and pretty much anywhere else
we can get away with it. When you customize your Windows 2000 or NT
environment and applications, the changes end up in subkeys of HKCU,
which is actually a link to your SID's subkey under HKU. Only a
currently logged-in user has access to HKCU. It can't be edited
remotely (RegEdit disallows remote user access
to HKCU and HKCC), nor can a SID key under HKU be edited while
someone with a different SID is logged in.
The contents of HKCU vary more than any of the other root keys
because applications store their user-specific settings here too. If
Ellen and Joe share a computer, their respective HKCU subkeys can end
up looking very different: Ellen might install and use Netscape,
Visual Studio, and BoundsChecker, while Joe might stick with Office
2000 and Internet Explorer. Accordingly, in this section I'll
confine my discussion to the most important subkeys of HKCU.
11.7.1 HKCU\ AppEvents
For
better or worse,
Microsoft included the capability in
NT 4.0 (and Win95, too) to associate sounds with system events such
as opening or closing windows, logging out, and so on. This feature
certainly falls into the customization arena, and application
developers can add their own event classes. For example, if you
install Microsoft's Visual Studio, you can get audio alerts
when your compilation succeeds, when the debugger hits a breakpoint,
and so on.
The event-to-sound mappings are stored in HKCU\AppEvents. Each event
that has a sound associated with it has the name of the
.wav file to play as the content of its default
value. For a fun prank, write a Perl script that randomly assigns
.wav files from
%systemroot%\media to random events.
11.7.2 HKCU\Console
MS-DOS command-line interface is, to
put it politely, extremely limited. If you're used to a
powerful Unix shell such as bash,
zsh, or tcsh, you know what
I mean. The really weak spot, though, is the appearance and behavior
of the console window; after all, you can always write command
scripts in Perl, KixStart, or REXX, but you're stuck looking at
them through that old throwback 80x24 white-on-black ugly-font DOS
window!
Fortunately, the Windows 2000 and NT console is customizable, so you
don't have to suffer any longer. The customization settings all
live under HKCU\Console, and they're so self-explanatory (guess
what FontSize does) I won't cover them here.
11.7.3 HKCU\Control Panel Items
Each installed control panel may have
its own subkey and settings beneath HKCU\Control Panels. HKU\.DEFAULT
has default settings for all the control panels, so HKCU\Control
Panels may not contain as many values as you'd expect.
Additionally, many control panels (notably Network and Multimedia)
store their settings in other parts of the Registry.
11.7.4 HKCU\Environment
The
Environment key contains whatever
environment variables are set in the "User Variables"
list of the System control panel's Environment tab.
They're stored as name-value pairs. For some reason, some
variables are stored as REG_SZ entries, while others are stored as
REG_EXPAND_SZ. It doesn't seem to matter what's in the
value, either; some nonexpandable strings are still tagged as
REG_EXPAND_SZ. Weird.
11.7.5 HKCU\Printers
The system stores information about
printers the current user may use in HKCU\Printers. Each printer gets
its own value entry directly under HKCU\Printers. This entry
specifies what the default printer for this particular user is. The
printer settings themselves (for all printers, not just the default
one) are actually stored in
HKLM\SYSTEM\CurrentControlSet\Control\Print\Printers for Windows 2000
machines and HKLM\SYSTEM\CurrentControlSet\Services\Print\Printers
for NT.
11.7.6 HKCU\Software\Microsoft
As you've no doubt inferred from
the name, user-specific settings for Microsoft components are stored
under this key. Until you install Internet Explorer and/or Microsoft
Office on a machine, though, there are relatively few of these keys;
most system settings are stored under HKLM, and there aren't
that many settings to hold here.
11.7.6.1 Microsoft\
NtBackup
The bundled backup applications
included with Windows 2000 and NT have a fairly large number of
settings in it. All these settings can be manipulated using the
program's standard user interface, but you may be interested in
setting some of them via group or system policies. For example, the
NtBackup\UserInterface\UsePassword flag can be set to require that
backup tapes be password-protected. There are a number of subkeys
that fall under Microsoft\NtBackup:
- Backup Engine
The values under this subkey control the actual backup process: how
many buffers should be reserved for the tape drive, whether Mac files
on an NTFS volume should be backed up, and so forth. - Debug
If you're having problems getting a backup device to work, you
can configure debug logging through the values in this key. - Display
These settings store your choices of font size, window position, and
other display parameters. - Hardware
The settings you choose for whatever type of tape hardware your
system has are stored here. - Logging
You can turn on logging for individual backup jobs through the
ntbackup user interface. When you do, these
values are used to figure out whether the log file should be printed
and what the root of its filename should be. - Translators
These settings store NT Backup translator information. - User Interface
The catch-all key, this holds values that don't have a place
anywhere else, such as whether the tape should be ejected when the
backup completes or whether the backup should be automatically
verified when it's done.
For a more complete explanation of the ins and outs of
NTBACKUP, see O'Reilly's
Windows NT Backup and Restore.
11.7.6.2 Microsoft\
RAS Autodial
The Dial-Up Networking autodialer's settings are stored under
this key, which retains its name for backward compatibility.
- Addresses
Each time you establish an autodialed connection, DUN stores the
address that caused the dialing in a value under Addresses. The IP
address or DNS name serves as the value name for each entry. Entries
under Addresses have three values: Tag, LastModified, and Network. - Control
This subkey is where the actual control settings for the autodialer
live. There are only three of them:
- DisabledAddresses
This REG_MULTI_SZ stores a list of IP addresses or DNS names for
which an autodialed connection will never be established. You can use
this list as an extremely low-rent blocking proxy by filling it with
addresses of sites you don't want to connect to. - LoginSessionDisable
I have no idea what this is for. It appears to be set by the
RasGet-AutodialParm( ) API routine. If you know
what this does, I'd love to hear. - DisableConnectionQuery
Ordinarily, DUN pops up a little dialog asking you for permission to
start a connection when it needs one. This is annoying because if you
start something that requires a connection, you have to stay there to
answer the dialog; its default action button is "No,
don't dial." You can subdue this annoyance by setting
DisableConnectionQuery (a REG_DWORD) to 1. This forces DUN to always
start a dialup connection when one is required. - Locations
There's one subkey of Locations for each dialing location you
have defined. - Entries
Likewise, there is one subkey under Entries for each phonebook entry
you've used. The value for an entry is of the form NetworkX,
where X is some small integer. This indicates which DUN dialup
adapter you used to make this connection. - Networks
This key has subkeys named after the values of Entries'
subkeys: Network0, Network1, and so on. Each of these entries in turn
has a value named "1" that points back to an entry under
Entries.
11.7.6.3 Microsoft\RAS Monitor
The RAS Monitor key stores settings
for the Dial-Up Networking monitor. Nine of the fourteen values
stored here track the window size and position of various monitor
windows; the other five are flag and setting values whose structure
isn't documented.
11.7.6.4 Microsoft\RAS Phonebook
The systemwide set of DUN phonebook entries is stored in
%systemroot%\system32\ras\rasphone.pbk. This
file (or the personal phonebook files you can create and use instead)
holds the phone numbers, network settings, and login credentials for
each entry in your phonebook. These settings
can differ widely between entries; you might have one entry for your
ISP that tells DUN to use server-supplied values for everything and
another for dialing in to your office intranet that uses a fixed set
of IP, DNS, and gateway addresses.
The values beneath Microsoft\RAS Phonebook control DUN dialing for
all entries in the phonebook. As you can see, they provide a fairly
rich set of options.
- AllowLogonLocationEdits and AllowLogonPhonebookEdits
These two REG_DWORD s control whether users may change their dialing
location or phonebook entry during login. They're only
effective if you've enabled the option to allow logging on via
DUN. Note that when you change these parameters in the Appearance tab
of the Logon Properties dialog from within
rasphone, these values are actually changed in
HKU\.DEFAULT\Software\Microsoft\RAS Phonebook, not in HKCU. - AlternatePhonebookPath
If you specify an alternate phonebook in the User Preferences
dialog's Phonebook tab, the path to that phonebook appears
here. - AreaCodes
In the Basic tab of the Edit Phonebook Entry dialog, you can specify
whether you want to use the TAPI dialing properties or not. If you
do, you can enter an area code for the phonebook number. This
REG_MULTI_SZ tracks the area codes you've entered in the
phonebook. - CallbackMode
DUN supports three callback modes via this value. They apply only if
the remote server offers to perform a callback. The first option, set
if this REG_DWORD is 0, tells the DUN client to refuse callback
requests. A value of 1 (the default) specifies that DUN should ask
you whether you want to accept it or not, and a value of 3 means
"yes, always accept a callback if requested." - CloseOnDial
When it's set to 1, as it is by default, this REG_DWORD tells
DUN to close the phonebook application when it's finished. Set
this value to
to keep the phonebook application open after dialing completes. - DefaultEntry
This REG_SZ specifies which phonebook entry appears as the default
entry when you open the Dial-Up Networking phonebook. Adjust it to
make a particular entry appear. - ExpandAutoDialQuery
Before DUN autodials for you, it may ask you to confirm that you
really want to dial (unless you have "Always prompt before
auto-dialing" unchecked in the Appearance tab of the User
Preferences dialog). When it does ask for confirmation, the
"Settings" button in the confirmation dialog shows
additional controls for choosing a location and turning off the
confirmation requests in the future. Setting ExpandAutoDialQuery to
1, its default, makes these extra controls immediately visible.
Setting it to
requires users to hit the Settings button to see them. - IdleHangUpSeconds
This value specifies the number of seconds a DUN connection may be
idle before the client hangs it up. The value should be in seconds; a
value of
tells DUN to never hang up. - LastCallbackByCaller
I don't know what this is for either. - NewEntryWizard
As with so many other Windows 2000 and NT components, the DUN
phonebook features a wizard that ostensibly helps you create new
entries. The Appearance tab of the User Preferences dialog features a
checkbox that lets you specify whether you want to use the wizard or
not; this REG_DWORD reflects that value. - OperatorDial
You can toggle a DUN setting that tells it not to dial because
you'll be dialing manually. This REG_DWORD value reflects that
option; when it's 1, that means that the system waits for you
to dial before attempting to connect. - PersonalPhonebookFile
Besides the alternate phonebook file, you may specify an individual
phonebook file for your own use (after all, this is HKCU !). If you
specify a personal phonebook in the User Preferences dialog's
Phonebook tab, the path to that phonebook appears here. - PhonebookMode
This REG_DWORD specifies which phonebook DUN uses. The default value
of
means that
%systemroot%\system32\ras\rasphone.pbk is used;
a value of 1 means that the user's personal phonebook is used,
and a 3 means that the value in AlternatePhonebookPath is used. - Phonebooks
This REG_MULTI_SZ keeps a list of all the phonebooks you've
ever specified in AlternatePhonebookPath so it can build a combo box
listing them for your later reference. - Prefixes
This REG_MULTI_SZ contains a list of all the prefixes you've
ever specified for phone entries in your phonebook. This allows DUN
to present a nice combo box listing your previous choices. - PreviewPhoneNumber
This REG_DWORD reflects the setting of the "Preview Phone
Number" checkbox in the Appearance tab of the Edit Phonebook
Entry dialog. When it's set to 1, users may edit the phonebook
entry's number before it's dialed. - RedialAttempts
By default, if a connection doesn't happen on the first
attempt, DUN quits trying. This happens because the default value of
RedialAttempts is 0. You can enable as many retries as you'd
like, and DUN will patiently keep trying until it connects or makes
the specified number of attempts. - RedialOnLinkFailure
This value (a REG_DWORD) specifies whether DUN should automatically
resurrect a failed connection. Sometimes a connection drops for no
good reason; setting this value to 1 causes DUN to redial and restart
the connection if it fails. - RedialSeconds
This value specifies the number of seconds (15 is the default) to
wait between redial attempts, assuming you've set
RedialAttempts to greater than 0. - ShowConnectStatus
This REG_DWORD has two possible values: 1 (the default) displays a
connection progress dialog that indicates what's happening on
the connection, and
suppresses the dialog (useful when you're making connections
via command-line scripts). - ShowLights
In a nod to the Win95 way of doing things, NT's DUN can display
some little blinking lights in the system tray to duplicate the
front-panel LEDs of most external modems. The Dial-Up Networking
Monitor is in charge of this vital function. By default, this
REG_DWORD's value is 1, meaning that the DUN Monitor will be
started before the connection is--therefore, the lights will be
present. If you don't enjoy seeing them (or, more likely, if
you're not paying any attention to the system tray), you can
set this value to
to hide them. - SkipConnectComplete
Until you tell it otherwise, DUN displays a dialog saying
you've successfully connected. One of the options in this
dialog is a checkbox that says "Don't show this dialog
again." That checkbox controls the value of
SkipConnectComplete: when it's 1, that tells DUN to omit the
dialog. By default, its value is 0, so you'll see this dialog
until you manually turn it off. - Suffixes
Like Prefixes, this value's a REG_MULTI_SZ. Its purpose is to
store a list of any suffixes you've ever specified for a DUN
phone number. - UseLocation
By default, you can select any of the installed TAPI locations when
making a DUN connection. This is especially useful if you have a
machine that frequently moves between different area codes or
countries. However, if you want to keep users from changing their
location from the DUN phonebook, just set this REG_DWORD to
instead of its default value of 1. (Note that users can still use the
Modems control panel to change locations.) - UseAreaAndCountry
I haven't been able to identify what this does. - WindowX and WindowY
These values specify the (x,y) location of the upper-left corner of
the DUN phonebook window.
Besides this cornucopia of values, Microsoft\RAS Phonebook has an
additional subkey, Callback. Every installed modem device on
the system has its own subkey under Callback, named after the device
(e.g., Callback\Standard Modem (COM2)). If you set the callback mode
to "always call me back at this number," the number you
supply for that device goes in the subkey's Number value. This
provides a convenient way to preset a callback number, perhaps as
part of a mass laptop installation.
11.7.6.5 Microsoft\Windows\CurrentVersion
A surprising amount of code originally
developed for Win95 has found its way into NT 4.0 and ultimately
Windows 2000. In fact, Microsoft's eventual goal is to unify
the Win9x and NT lines until what's left is a nice Win9x
interface over the security, performance, and scalability of NT. To
facilitate this merging, Microsoft included a compatibility key,
Microsoft\Windows\CurrentVersion, in the NT 4.0 and Windows 2000
Registries. This allows applications that use this key on Win95, like
Explorer and Internet Explorer, to run on NT and Windows 2000 systems
without modification.
11.7.6.6 Microsoft\Windows NT\CurrentVersion
Much like the Microsoft\Windows subkey which holds information for
applications that were designed to run on Win95 machines, this
Windows 2000 subkey contains subkeys that represent different
versions of Windows 2000, NT 4.0 and earlier. Most notably, the
CurrentVerions subkey stores user-specific configuration data for
programs that are designed to run on the latest version of Windows
2000.
The Microsoft\Windows NT key appears to be a migration of the
previous NT key HKCU\Microsoft\Windows NT. They both contain subkeys
that represent the current operating system versions (see the next
section) and contain similar keys and values, with the following
Windows 2000 additions:
- Event Viewer
Event Viewer is a Windows 2000 MMC snap-in that displays event logs
written to by Windows 2000 applications and services. The Event
Viewer subkey stores information about the configuration of this
snap-in. - Extensions
Through Window Explorer (or the Registry), you can associate filename
extensions with programs that are run when you open the file. Values
under this subkey specify default command line executions for
filename extensions that are not associated with programs. - PrinterPorts
Entries under this subkey contain information about printers, such as
name, driver name, port, and timeout value, that the client is
connected to. - Task Manager
Task Manager is a performance tool that displays application,
process, and performance information (you've likely used it if
you've ever had to terminate a application that wasn't
responding). This subkey contains Task Manager preferences. - TrueType
This subkey contains information about the display of TrueType fonts.
11.7.7  HKCU\Microsoft\Windows NT\CurrentVersion
This key is pretty much a mixed bag: it
holds user-specific settings that have no home elsewhere. For
example, NT's Server Manager applications store their settings
in a subkey of Windows NT\CurrentVersion\Network even though they
might more properly live under HKCU\Software\Microsoft\ServerManager
or somesuch.
- Devices
The Devices subkey contains one value entry for each installed
printer on a system. Apart from that, it doesn't seem to do
anything else. - Network
The Event Viewer, Server Manager, and User Manager all keep their
small sets of user-specific settings here. The only other interesting
item is the PersistentConnections subkey, which contains a list of
shares that NT should reconnect when the user logs in again. - Program Manager
The entries under this key are retained for older applications that
expect to find things here. - Windows
Just as with Program Manager, this key primarily exists for backward
compatibility, especially with the WOW subsystem. - Winlogon
Alone among the subkeys of Windows NT\CurrentVersion, Winlogon
actually has three useful values beneath it. They duplicate similar
entries in HKLM\SOFTWARE\Microsoft\Windows
NT\CurrentVersion\Winlogon, but these entries apply only to the
currently logged in user.
- ParseAutoexec
This REG_DWORD specifies whether to parse
autoexec.bat when the user logs in, resulting in
the autoexec.bat path statement being appended
to the system path created by Windows NT. 1 (the default) means yes;
means no. - ProfileType
Specifies the profile type of the current user's profile. A 1
means it's a local profile; other values indicate a cached,
roaming, or mandatory roaming profile. - RunLoginScriptSync
If this REG_DWORD is set to 1, any logon script for this user is run
before the desktop and shell are started. This is the default.
Setting the value to
allows the logon script process to run in parallel with the shell
as it
starts.
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