Manual Editing.

The Windows registry can be edited manually in Microsoft Windows by running regedit.exe or regedt32.exe in the Windows directory. However, careless registry editing can cause irreversible damage. Thus, performing back-up for registry is needed. Many optimization and "hacking" tools are available to modify this portion of the Windows operating system. It is preferable to use one of the many registry tools available, unless you have a knowledge of registry workings or wish to learn more about the registry, in which case it is recommended that you back up your hard drive before changing the registry.

A simple implementation of the current registry tool appeared in Windows 3.x, called the "Registration Info Editor" or "Registration Editor". This was basically just a database of applications used to edit embedded OLE objects in documents.

Windows NT introduced permissions for Registry editing. Windows NT 4 and Windows 2000 were distributed with both the Windows 9x REGEDIT.EXE program and Windows NT 3.x's REGEDT32.EXE program. There are several differences between the two editors on these platforms:

* REGEDIT.EXE had a left-side tree view that began at "My Computer" and listed all loaded hives. REGEDT32.EXE had a left-side tree view, but each hive had its own window, so the tree displayed only keys.

* REGEDIT.EXE represented the three components of a value (its name, type, and data) as separate columns of a table. REGEDT32.EXE represented them as a list of strings.

* REGEDIT.EXE supported right-clicking of entries in a tree view to adjust properties and other settings. REGEDT32.EXE required all actions to be performed from the top menu bar.

* Because REGEDIT.EXE was directly ported from Windows 95, it did not support permission editing (permissions do not exist on Windows 9x). Therefore, the only way to access the full functionality of an NT registry was with REGEDT32.EXE.

* REGEDIT.EXE only supported string (REG_SZ), binary (REG_BINARY), and DWORD (REG_DWORD) values. REGEDT32.EXE supports those, plus expandable string (REG_EXPAND_SZ) and multi-string (REG_MULTI_SZ). Attempting to edit unsupported key types with REGEDIT.EXE on Windows 2000 or Windows NT 4 will result in conversion to a supported type that cannot be reversed.[1]

Windows XP was the first system to integrate these two programs into one, adopting the old REGEDIT.EXE interface and adding the REGEDT32.EXE functionality. The differences listed above are not applicable on Windows XP and newer systems; REGEDIT.EXE is the improved editor, and REGEDT32.EXE is simply a stub that invokes REGEDIT.EXE.

 

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Command Line Editing

On NT-based systems the registry can be manipulated from the command line with the reg.exe utility. It is included in Windows XP and can be downloaded separately for previous versions.

reg.exe Operation [Parameter List]

Operation [QUERY|ADD|DELETE|COPY|SAVE|LOAD|UNLOAD|RESTORE|COMPARE|EXPORT|IMPORT]

Also, a .reg file (a text-based human-readable file format for storing portions of the registry) can be imported from the command line with the following command:

regedit.exe /s file

The /s means the file will be silent merged to the Registry. If the /s parameter is omitted the user will be asked to confirm the operation. In Windows 98 and Windows 95 the /s switch also caused regedit.exe to ignore the setting in the registry that allows administrators to disable it. When using the /s switch Regedit does not return an appropriate return code if the operation fails, unlike reg.exe which does. This makes it hard to script, however a possible workaround is to add the following lines into your batch file:

regedit /s file.reg
regedit /e test.reg "key"
if not exist test.reg goto REGERROR
del test.reg

The default association for .reg files in many versions of Microsoft Windows, starting with Windows 98 does require the user to confirm the merging to avoid user mistake.

Editing By Programs Or Scripts

You can edit the registry through the APIs of the Advanced Windows 32 Base API Library (advapi32.dll).

This is a list of the Registry API Functions:

RegCloseKey RegOpenKey
RegConnectRegistry RegOpenKeyEx
RegCreateKey RegQueryInfoKey
RegCreateKeyEx RegQueryMultipleValues
RegDeleteKey RegQueryValue
RegDeleteValue RegQueryValueEx
RegEnumKey RegReplaceKey
RegEnumKeyEx RegRestoreKey
RegEnumValue RegSaveKey
RegFlushKey RegSetKeySecurity
RegGetKeySecurity RegSetValue
RegLoadKey RegSetValueEx
RegNotifyChangeKeyValue RegUnLoadKey

Another way is to use the Windows Support Tool Reg.exe by executing it from your code.

Many scripting languages such as Perl and Visual Basic also enable registry editing from scripts.


Useful Registry Keys.

The following registry keys may be of interest to users attempting to customize their Windows systems.

* HKLM\System\CurrentControlSet\Control\FileSystem\NtfsDisableLastAccessUpdate Creating this (as a DWORD) and setting it to 1 will prevent Windows (NT, 2000 or XP) from tracking the last access time of files, which speeds up a lot of operations (especially opening folders of items with previews).

* HKLM\System\CurrentControlSet\Services\LanmanServer\Parameters\SizReqBuf Specifies the size of buffers used for storing requests to the file/print server. Increasing this from the default of 4356 bytes can improve network performance: a figure of 14596 is frequently recommended.

* HKLM\Software\Microsoft\Windows\CurrentVersion\Run (and the HKCU equivalent) specifies applications to run whenever a user logs in. These can include desirable programs, such as printer monitoring programs or frequently-used tools, but a lot of malware uses this registry key to ensure it is automatically run. This key is a common place to start looking for evidence of malware if a computer has been infected.

The following registry tweaks are available from Windows Registry Hacks at PCWorld.com, and are for Windows XP Home/Professional unless noted:

* HKCU\Control Panel\Desktop (note: the last word may appear as desktop). Double-click the MenuShowDelay icon on the right, and change 'Value data' from its default of 400 (milliseconds) to something speedier, like 0, or slower, to 4000 (4 seconds). This determines how long to delay before showing a clicked/selected menu, such as File, or the Start Menu after being clicked.

* HKCU\Control Panel\Desktop. Double-click the AutoEndTasks icon in the right pane, change 'Value data' to 1. This is defaulted to 0. Setting it to 1 allows Windows to automatically end processes that are unresponsive or frozen. This is particularly useful when shutting down or resetting.

* HKCU\Control Panel\Desktop. HungAppTimeout icon is located in the right pane. Select 'Value data' to change it from the default (5000 milliseconds, or 5 seconds), to something quicker, like 2500 (2.5 seconds). This is similar to AutoEndTasks, only this focuses on currently running Programs, instead of processes.

* HKCU\Control Panel\Desktop. WaitToKillAppTimeout determines how long to wait before shutting down *any* prorgam that is unresponsive during the shut-down/reset sequence. The default is 20000 (20 seconds), but 10000 (10 seconds) should suffice. Simply alter it to how long (or short) you wish to wait, in milliseconds.

* HKLM\SYSTEM\CurrentControlSet\Control. Double-click the WaitToKillServiceTimeout icon in the right pane. This is for Windows' system processes that have become unresponsive/frozen, particularly during shutting down or resetting. Adjust its 'Value data' (also 20000 milliseconds, or 20 seconds, by default) to the wait time of your choice, and press <Enter>. Note: Your new value may not stick, since some services automatically increase this number to build in more time to clean up their act or shut down properly.

* HKCU\Control Panel\desktop. Double-click the WallpaperOriginX icon in the right pane. (If you don't see this icon, right-click in this pane, choose New, String Value, type WallpaperOriginX to name the value, and press <Enter>.) Type a number (in pixels) for the starting horizontal position of your wallpaper's left edge, and press <Enter>. Now double-click the WallpaperOriginY icon (create it if necessary as explained above) and enter a number for the starting vertical position of the image's top edge. If your wallpaper image is larger than the screen, type a negative number (for example, -200) to push the picture's top or left edge off the screen. This is useful for users that have upgraded to widescreen monitors, or who simply want custom resolutions or ratios for their desktop wallpaper.

* HKLM\SYSTEM\CurrentControlSet\Control\ContentIndex. Double-click the FilterFilesWithUnknownExtensions icon in the right pane, change the 0 in the 'Value data' box to 1, and press <Enter>. This is very useful in coaxing the Windows Search utility to find *every* file, instead of only those with known file extensions, such as .exe, .zip, .rtf, or .jpg.

* HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList. Search for the DWORD value named "Administrator", and double-click the Administrator icon in the right pane. (If you don't see this icon, right-click in the pane, choose New, DWORD Value, name it Administrator, and press <Enter>.) Type 1 in the 'Value data' box, and press <Enter>. From now on, when you open the User Accounts window via the Control Panel (choose Start, Run, type Control userpasswords, and press <Enter>), you'll see the Administrator account. This is extremely useful for recovering from hardware issues and system failures, and for those who simply want to show the Administrator at Windows Logon.

* HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main. In the Registry Editor, double-click the Window Title icon in the right pane. (If you don't see this icon, right-click in the pane, choose New, String Value, type Window Title, and press <Enter>.) Type what you want to see on IE's title bar, or type nothing to show only the site name. Note that the hyphen that normally separates the site name from the page title will remain. The changes will be shown upon closing all Internet Explorer windows, and re-launching the application.

If you would prefer not to tinker with your registry yourself it is advisable to leave registry maintenance to Error Smart registry cleaner, this is the safest way to keep your Windows registry in good shape.

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