Get-EventSubscriber
Gets the event subscribers in the current session.
Syntax
Get-EventSubscriber
[[-SourceIdentifier] <String>]
[-Force]
[<CommonParameters>] Get-EventSubscriber
[-SubscriptionId] <Int32>
[-Force]
[<CommonParameters>] Description
The Get-EventSubscriber cmdlet gets the event subscribers in the current session.
When you subscribe to an event by using a Register event cmdlet, an event subscriber is added to
your Windows PowerShell session, and the events to which you subscribed are added to your event
queue whenever they are raised. To cancel an event subscription, delete the event subscriber by
using the Unregister-Event cmdlet.
Examples
Example 1: Get the event subscriber for a timer event
This example uses a Get-EventSubscriber command to get the event subscriber for a timer event.
The first command uses the New-Object cmdlet to create an instance of a timer object. It saves the
new timer object in the $Timer variable.
The second command uses the Get-Member cmdlet to display the events that are available for timer
objects. The command uses the Type parameter of the Get-Member cmdlet with a value of Event.
$Timer = New-Object Timers.Timer
$Timer | Get-Member -Type Event
TypeName: System.Timers.Timer
Name MemberType Definition
---- ---------- ----------
Disposed Event System.EventHandler Disposed(System.Object, System.EventArgs)
Elapsed Event System.Timers.ElapsedEventHandler Elapsed(System.Object, System.Timers.ElapsedEventArgs)
Register-ObjectEvent -InputObject $Timer -EventName Elapsed -SourceIdentifier Timer.Elapsed
Get-EventSubscriber
SubscriptionId : 4
SourceObject : System.Timers.Timer
EventName : Elapsed
SourceIdentifier : Timer.Elapsed
Action :
HandlerDelegate :
SupportEvent : False
ForwardEvent : FalseThe third command uses the Register-ObjectEvent cmdlet to register for the Elapsed event on
the timer object.
The fourth command uses the Get-EventSubscriber cmdlet to get the event subscriber for the
Elapsed event.
Example 2: Use the dynamic module in PSEventJob in the Action property of the event subscriber
This example shows how to use the dynamic module in the PSEventJob object in the Action property of the event subscriber.
The first command uses the New-Object cmdlet to create a timer object. The second command sets the
interval of the timer to 500 (milliseconds).
$Timer = New-Object Timers.Timer
$Timer.Interval = 500
$params = @{
InputObject = $Timer
EventName = 'Elapsed'
SourceIdentifier = 'Timer.Random'
Action = { $Random = Get-Random -Min 0 -Max 100 }
}
Register-ObjectEvent @params
Id Name State HasMoreData Location Command
-- ---- ----- ----------- -------- -------
3 Timer.Random NotStarted False $Random = Get-Random ...
$Timer.Enabled = $True
$Subscriber = Get-EventSubscriber -SourceIdentifier Timer.Random
($Subscriber.action).gettype().fullname
System.Management.Automation.PSEventJob
$Subscriber.action | Format-List -Property *
State : Running
Module : __DynamicModule_6b5cbe82-d634-41d1-ae5e-ad7fe8d57fe0
StatusMessage :
HasMoreData : True
Location :
Command : $random = Get-Random -Min 0 -Max 100
JobStateInfo : Running
Finished : System.Threading.ManualResetEvent
InstanceId : 88944290-133d-4b44-8752-f901bd8012e2
Id : 1
Name : Timer.Random
ChildJobs : {}
...
& $Subscriber.action.module {$Random}The third command uses the Register-ObjectEvent cmdlet to register the Elapsed event of the timer
object. The command includes an action that handles the event. Whenever the timer interval elapses,
an event is raised and the commands in the action run. In this case, the Get-Random cmdlet
generates a random number between 0 and 100 and saves it in the $Random variable. The source
identifier of the event is Timer.Random.
When you use an Action parameter in a Register-ObjectEvent command, the command returns a
PSEventJob object that represents the action.
The fourth command enables the timer.
The fifth command uses the Get-EventSubscriber cmdlet to get the event subscriber of the
Timer.Random event. It saves the event subscriber object in the $Subscriber variable.
The sixth command shows that the Action property of the event subscriber object contains a
PSEventJob object. In fact, it contains the same PSEventJob object that the
Register-ObjectEvent command returned.
The seventh command uses the Format-List cmdlet to display all of the properties of the
PSEventJob object in the Action property in a list. The result reveals that the PSEventJob
object has a Module property that contains a dynamic script module that implements the action.
The remaining commands use the call operator (&) to invoke the command in the module and display
the value of the $Random variable. You can use the call operator to invoke any command in a module,
including commands that are not exported. In this case, the commands show the random number that is
being generated when the Elapsed event occurs.
For more information about modules, see about_Modules.
Example 3: Get hidden event subscribers
This example registers an event subscriber for the PowerShell.Exiting event. The subscription is
registered using the SupportEvent parameter, which hides the event subscriber from the default
output of the Get-EventSubscriber cmdlet. You must use the Force parameter to get all event
subscribers, including hidden subscribers.
Register-EngineEvent -SourceIdentifier PowerShell.Exiting -SupportEvent -Action {
Get-History | Export-Clixml d:\temp\history.clixml
}
Get-EventSubscriber # No output - must use -Force
Get-EventSubscriber -Force
SubscriptionId : 1
SourceObject :
EventName :
SourceIdentifier : PowerShell.Exiting
Action : System.Management.Automation.PSEventJob
HandlerDelegate :
SupportEvent : True
ForwardEvent : FalseParameters
-Force
Indicates that this cmdlet gets all event subscribers, including subscribers for events that are
hidden by using the SupportEvent parameter of Register-ObjectEvent, Register-WmiEvent, and
Register-EngineEvent.
| Type: | SwitchParameter |
| Position: | 1 |
| Default value: | None |
| Required: | False |
| Accept pipeline input: | False |
| Accept wildcard characters: | False |
-SourceIdentifier
Specifies the SourceIdentifier property value that gets only the event subscribers. By default,
Get-EventSubscriber gets all event subscribers in the session. Wildcards are not permitted. This
parameter is case-sensitive.
| Type: | String |
| Position: | 0 |
| Default value: | None |
| Required: | False |
| Accept pipeline input: | True |
| Accept wildcard characters: | False |
-SubscriptionId
Specifies the subscription identifier that this cmdlet gets. By default, Get-EventSubscriber gets
all event subscribers in the session.
| Type: | Int32 |
| Aliases: | Id |
| Position: | 0 |
| Default value: | None |
| Required: | True |
| Accept pipeline input: | True |
| Accept wildcard characters: | False |
Inputs
None
You can't pipe objects to this cmdlet.
Outputs
This cmdlet returns a PSEventSubscriber object for each event subscriber.
Notes
The New-Event cmdlet, which creates a custom event, does not generate a subscriber. Therefore, the
Get-EventSubscriber cmdlet will not find a subscriber object for these events. However, if you use
the Register-EngineEvent cmdlet to subscribe to a custom event (in order to forward the event or
to specify an action), Get-EventSubscriber will find the subscriber that Register-EngineEvent
generates.
Events, event subscriptions, and the event queue exist only in the current session. If you close the current session, the event queue is discarded and the event subscription is canceled.
