INFO: Run, RunOnce, RunServices, RunServicesOnce and Startup

ID: Q179365

The information in this article applies to:

Microsoft Windows NT versions 3.51, 4.0
Microsoft Windows 95
Microsoft Windows 98
Microsoft Windows 2000

SUMMARY

This article explains how the Run, RunOnce, RunServices, RunServicesOnce, and RunOnce\Setup registry keys relate to each other and to the Startup Folder. It also describes the order in which these keys are loaded.

The information contained in this article is supplements the following article in the Microsoft Knowledge Base:

Q137367 Definition of the RunOnce Keys in the Registry

Please see this article for an explanation of each of these keys.

MORE INFORMATION

Under Windows 95 and Windows 98, where all keys are supported, the keys are loaded in the following order:

   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServicesOnce


   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices<Logon Prompt>


   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce


   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run


   HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run StartUp Folder


   HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce

With the exception of the HKEY_LOCAL_MACHINE\...\RunOnce key, all keys and their entries are loaded asynchronously. Therefore, all entries in the RunServices and RunServicesOnce keys can potentially run at the same time.

Entries in the HKEY_LOCAL_MACHINE\...\RunOnce key are loaded synchronously in the order they were added to the RunOnce key. (This is not necessarily the order in which these entries are displayed by the Registry Editor.)

Since the HKEY_LOCAL_MACHINE\...\RunOnce key is loaded synchronously, all of its entries must finish loading before the HKEY_LOCAL_MACHINE\...\Run, HKEY_CURRENT_USER\...\Run, HKEY_CURRENT_USER\...\RunOnce, and Startup Folder entries can be loaded.

The RunServicesOnce and RunServices keys are loaded before the user logs into Windows 95. Because these two keys run asynchronously with the Logon dialog box, they can continue to run after the user has logged on. However, since HKEY_LOCAL_MACHINE\...\RunOnce must load synchronously, its entries will not begin loading until after the RunServicesOnce and RunServices keys have finished loading.

Because of different system configurations (such as a computer that is configured to automatically log on), any application that is dependant upon other applications that are executed under these keys having completed must be prepared to wait until these applications are complete. Other than this exception, the above description applies to Windows NT 4.0 and Windows 2000.

The RunOnce key is not supported by Windows NT 3.51.

REFERENCES

For additional information, please see the following article in the Microsoft Knowledge Base:

Q137367 Definition of the RunOnce Keys in the Registry

Additional query words: Run RunOnce RunServices RunServicesOnce Startup registry

Keywords : kbKernBase kbNTOS351 kbNTOS400 kbWinOS2000 kbRegistry kbWinOS95 kbWinOS98 kbDSupport kbshell kbGrpKernBase
Version : WINDOWS:95; winnt:3.51,4.0
Platform : WINDOWS winnt
Issue type : kbinfo