Check if no user is currently logged on to Windows

Question

I'm writing a Windows Service application which listens for connections and performs certain tasks as instructed from a different application running on another computer on the network.

One of the tasks ensures no user is currently logged on, locks the workstation, delete some files, and then restarts the system. I considered using this solution to look through the list of running processes and check the user names, determining if no user is logged on by matchhing the user names against SYSTEM, NETWORK, etc. I realized I have PostgreSQL running which uses a user account named postgres so that wouldn't work. Checking if explorer.exe is running also wouldn't work because explorer sometmes crashes, or I sometimes end the process myself and restart it.

What would be a good way of determining that NO user is logged on to a workstation using C#?

Thanks a lot everyone. I'm not very good at using WMI and after hitting error after error, decided to go for flodin's answer. Here's a sample usage for anyone else interested: http://www.pinvoke.net/default.aspx/wtsapi32/WTSEnumerateSessions.html — Zahymaka, Feb 15 '09 at 21:37

score 16 · Accepted Answer · edited Feb 15 '09 at 20:05

16

Use WTSGetActiveConsoleSessionId() to determine whether anybody is logged on locally. Use WTSEnumerateSessions() to determine if there is any session at all (including remote terminal services sessions).

edited Feb 15 '09 at 20:05

onnodb

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answered Feb 15 '09 at 19:11

flodin

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Dan Ports · Answer 2 · 2019-09-16T23:02:45.643

8

Another option, if you don't want to deal with the P/Invokes: use Cassia.

using Cassia;

public static bool IsSomeoneLoggedOn(string server)
{
    foreach (ITerminalServicesSession session in new TerminalServicesManager().GetSessions(server))
    {
        if (!string.IsNullOrEmpty(session.UserName))
        {
            return true;
        }
    }
    return false;
}

edited Sep 16 '19 at 23:02

answered Apr 09 '09 at 03:06

Dan Ports

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what is `server` in this context? – Neil Galiaskarov Jul 06 '18 at 03:43
@NeilGaliaskarov Its obsolete now. Tested it with `new TerminalServicesManager().GetSessions()` in a domain user session and got my username via `session.UserName`. Otherwise you could check out `new TerminalServicesManager().GetLocalServer()` (I didn't test this one) – Icad May 04 '22 at 16:44

score 7 · Answer 3 · answered Jan 20 '13 at 15:08

7

You tried to check whether explorer.exe is running or not. Why not go for the winlogon.exe process?

public bool isLoggedOn()
{
    Process[] pname = Process.GetProcessesByName("winlogon");
    if (pname.Length == 0)
        return false;
    else
        return true;
}

answered Jan 20 '13 at 15:08

libjup

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Didn't work during startup, for me at least – Icad May 04 '22 at 16:48

score 3 · Answer 4 · answered Feb 15 '09 at 19:22

3

The CodeProject article "Using the Local Security Authority to Enumerate User Sessions in .NET" might be what you are looking for. The code enumerates users and can identify which users (if any) are interactive (i.e., which users are real people).

answered Feb 15 '09 at 19:22

snarf

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score 2 · Answer 5 · answered Feb 15 '09 at 19:15

2

You could use WMI

select UserName from Win32_ComputerSystem

answered Feb 15 '09 at 19:15

Alex Reitbort

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If someone down-votes this, please provide an explanation as to why. Is the answer wrong? Or are there just better ways to do this? – DOK Feb 15 '09 at 19:33
1

I don't like this answer, not down-voting, however. – unixman83 Sep 16 '11 at 22:43
WMI is expensive in terms of cycles and can be slow, but for a one-off query it's not an issue. If you are using WMI in a loop, it's expensive and you'll see things like wmiprvse.exe taking up CPU cycles – Jon R Mar 01 '21 at 17:12

Check if no user is currently logged on to Windows

5 Answers5

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