Wait-Event

Module:: Microsoft.PowerShell.Utility

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

Examples

Example 1: Wait for the next event

PS C:\> Wait-Event

This command waits for the next event that is raised.

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

PS C:\> Wait-Event -SourceIdentifier "ProcessStarted"

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

Example 3: Wait for a timer elapsed event

PS C:\> $Timer.Interval = 2000

PS C:\> $Timer.Autoreset = $False

PS C:\> $Timer.Enabled = $True; Wait-Event Timer.Elapsed

# After 2 seconds





EventIdentifier  : 12

Sender           : System.Timers.Timer

SourceEventArgs  : System.Timers.ElapsedEventArgs

SourceArgs       : {System.Timers.Timer, System.Timers.ElapsedEventArgs}

SourceIdentifier : Timer.Elapsed

TimeGenerated    : 6/10/2008 3:24:18 PM

MessageData      :

ForwardEvent     : False

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

Example 4: Wait for an event after a specified timeout

PS C:\> Wait-Event -SourceIdentifier "ProcessStarted" -Timeout 90

This command 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.

Optional Parameters

-SourceIdentifier

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

Type:	String
Position:	1
Default value:	None
Accept pipeline input:	True (ByPropertyName)
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:	None
Accept pipeline input:	False
Accept wildcard characters:	False

Inputs

System.String

Outputs

System.Management.Automation.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.