Introduction

This article is about locking, logging off, rebooting, shutting down, hibernating and putting the system on stand by mode in .Net. Here we are going to use both unmanaged code and .Net framework for these functions.

Getting Started

Let us start by creating a windows application. To our newly created form, add seven buttons entitled btnLockComp, btnLogOff, btnReboot, btnShutdown, btnForceLogOff, btnHibernate, btnStandby.

Lock, LogOff, Shutdown

Lock Workstation

Let us start with locking the workstation, which is supposed to lock the current user session. We will call a windows API for doing this. For calling an un-managed piece of code, we need to add the System.Runtime.InteropServices namespace to the using directive.

using System.Runtime.InteropServices;

Now we are ready to import the windows API library and define the function that we intend to use. The function to lock the workstation resides in the user32.dll library. And the function for locking the desktop is LockWorkStation. The following statements should be added to the class to import the library.

[DllImport("user32.dll")]
public static extern void LockWorkStation();

Next step is to double click the btnLockComp button to create a click event handler and call the LockWorkStation API to lock the workstation.

LockWorkStation();

Log Off

For logging off we are going to use an unmanaged API function called ExitWindowsEx(). This function accepts two arguments, one for flag(logoff, shutdown, reboot, etc.,) and the other for reason for this action(maintenance, software update, etc...). Now import the user32.dll once again, this time so we can use the ExitWindowsEx() function, as shown below:

[DllImport("user32.dll")]
public static extern int ExitWindowsEx(int uFlags, int dwReason);

Double click the log off button and add the following function call to the event. Flag 0 indicates logoff,

ExitWindowsEx(0, 0);

To force processes to terminate while logging off, change the flag to 4 in the function as below:

ExitWindowsEx(4, 0);

Reboot

To reboot we are going to use the same function ExitWindowsEx but with a different flag. Add the following code to the click event handler of the reboot button.

ExitWindowsEx(2, 0);

Shutdown

Now add the following code to the button Shutdown's click event handler.

ExitWindowsEx(1, 0);

Hibernate and Standby

To put the system in hibernate and standby modes, we are going to use Application class's SetSuspendState method. There are three arguments for this function, power state, force and disable wake event. The first argument, power state is where we mention the state of the system (hibernate/suspend).

// Hibernate
Application.SetSuspendState(PowerState.Hibernate, true, true);

// Standby
Application.SetSuspendState(PowerState.Suspend true, true);

Conclusion

Please note that these methods were only tested in Windows XP Home and Professional environments, however they should work on any systems that have .NET Framework installed.

Thats all folks!