Check logged on user

This script checks if a specific user is logged on to a specific system. The script will cath any error.
Status is OK if the user is logged on, and CRITICAL if not.
The computername, name of the domain and username are variable, so the script will accept any supplied value as an argument.

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Syntax:
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get_user.ps1 computername domain user

- For a remote system, the parameter computername can be a hostname, or an IP address. For the local machine, you can use localhost or a dot (.) as valid values.
- The parameter domain is the name of the domain (if the user is a domain user), or the computername (for a local user).
- The parameter user is the user logon name.

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Notes:
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- PowerShell scripts must be allowed to run on the target computer (PowerShell Script Execution Policy).
- Disconnected user sessions are recognized as logged on users. Which in fact is correct, because with a disconnected session, the user is still logged on to the system.

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Installation instructions:
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- Put the Powershell script in the C:\Program Files\NSClient++\Scripts directory.
- In the nsclient.ini file, in the section [/settings/external scripts/scripts], add the following line:
check_user=cmd /c echo scripts\\check_user.ps1 computername domain user; exit $LastExitCode | powershell.exe -command -
- Restart the NSClient
- On the Nagios server, create a service with the following check command:
check_command check_nrpe!check_user!
- Restart Nagios