Wait-Event

Waits until a particular event is raised before continuing to run.

Syntax

Wait-Event
    [[-SourceIdentifier] <String>]
    [-Timeout <Int32>]
    [<CommonParameters>]

Description

The Wait-Event cmdlet suspends execution of a script or function until a particular event is raised. Execution resumes when the event is detected. To cancel the wait, press CTRL+C.

This feature provides an alternative to polling for an event. It also allows you to determine the response to an event in two different ways:

  • using the Action parameter of the event subscription
  • waiting for an event to return and then respond with an action

Examples

Example 1: Wait for the next event

This example waits for the next event that is raised.

Wait-Event

Example 2: Wait for an event with a specified source identifier

This example waits for the next event that is raised and that has a source identifier of ProcessStarted.

Wait-Event -SourceIdentifier "ProcessStarted"

Example 3: Wait for a timer elapsed event

This example uses the Wait-Event cmdlet to wait for a timer event on a timer that is set for 2000 milliseconds.

$Timer = New-Object Timers.Timer
$objectEventArgs = @{
    InputObject = $Timer
    EventName = 'Elapsed'
    SourceIdentifier = 'Timer.Elapsed'
}
Register-ObjectEvent @objectEventArgs
$Timer.Interval = 2000
$Timer.Autoreset = $False
$Timer.Enabled = $True
Wait-Event Timer.Elapsed

ComputerName     :
RunspaceId       : bb560b14-ff43-48d4-b801-5adc31bbc6fb
EventIdentifier  : 1
Sender           : System.Timers.Timer
SourceEventArgs  : System.Timers.ElapsedEventArgs
SourceArgs       : {System.Timers.Timer, System.Timers.ElapsedEventArgs}
SourceIdentifier : Timer.Elapsed
TimeGenerated    : 4/23/2020 2:30:37 PM
MessageData      :

Example 4: Wait for an event after a specified timeout

This example waits up to 90 seconds for the next event that is raised and that has a source identifier of ProcessStarted. If the specified time expires, the wait ends.

Wait-Event -SourceIdentifier "ProcessStarted" -Timeout 90

Parameters

-SourceIdentifier

Specifies the source identifier that this cmdlet waits for events. By default, Wait-Event waits for any event.

Type:String
Position:0
Default value:None
Accept pipeline input:True
Accept wildcard characters:False
-Timeout

Specifies the maximum time, in seconds, that Wait-Event waits for the event to occur. The default, -1, waits indefinitely. The timing starts when you submit the Wait-Event command.

If the specified time is exceeded, the wait ends and the command prompt returns, even if the event has not been raised. No error message is displayed.

Type:Int32
Aliases:TimeoutSec
Position:Named
Default value:-1
Accept pipeline input:True
Accept wildcard characters:False

Inputs

String

Outputs

PSEventArgs

Notes

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.