[英]Powershell: Can Register-ObjectEvent watch for clipboard events?
[英]Make a Powershell respond to Register-ObjectEvent events in script mode
我有一個在Powershell ISE中編寫的簡單Powershell腳本。 其要點是,它監視命名管道進行寫操作,以作為執行操作的信號,同時監視其上司進程。 當老板進程退出時,腳本也會退出。 簡單。
在努力使命名管道在Powershell中正常運行而不會崩潰后,我設法獲得了工作代碼,如下所示。 但是 ,盡管此功能在Powershell ISE和交互式終端中運行良好,但我一直希望將其作為獨立腳本來使用是沒有希望的。
$bosspid = 16320
# Create the named pipe
$pipe = new-object System.IO.Pipes.NamedPipeServerStream(
-join('named-pipe-',$bosspid),
[System.IO.Pipes.PipeDirection]::InOut,
1,
[System.IO.Pipes.PipeTransmissionMode]::Byte,
[System.IO.Pipes.PipeOptions]::Asynchronous
)
# If we don't do it this way, Powershell crashes
# Brazenly stolen from github.com/Tadas/PSNamedPipes
Add-Type @"
using System;
public sealed class CallbackEventBridge
{
public event AsyncCallback CallbackComplete = delegate {};
private void CallbackInternal(IAsyncResult result)
{
CallbackComplete(result);
}
public AsyncCallback Callback
{
get { return new AsyncCallback(CallbackInternal); }
}
}
"@
$cbbridge = New-Object CallBackEventBridge
Register-ObjectEvent -InputObject $cbbridge -EventName CallBackComplete -Action {
param($asyncResult)
$pipe.EndWaitForConnection($asyncResult)
$pipe.Disconnect()
$pipe.BeginWaitForConnection($cbbridge.Callback, 1)
Host-Write('The named pipe has been written to!')
}
# Make sure to close when boss closes
$bossproc = Get-Process -pid $bosspid -ErrorAction SilentlyContinue
$exitsequence = {
$pipe.Dispose()
[Environment]::Exit(0)
}
if (-Not $bossproc) {$exitsequence.Invoke()}
Register-ObjectEvent $bossproc -EventName Exited -Action {$exitsequence.Invoke()}
# Begin watching for events until boss closes
$pipe.BeginWaitForConnection($cbbridge.Callback, 1)
第一個問題是腳本在執行任何有意義的操作之前先終止。 但是,使用while($true)
循環, -NoExit
標志, pause
命令或什至是為此目的而創建的特定命令(例如Wait-Event
while($true)
類的技巧來延遲執行的結束將導致進程保持打開狀態,但仍然不會使其響應事件。
我放棄了“正確”的方式,而是轉而使用包裹在while-true塊和Job控制中的同步代碼。
$bosspid = (get-process -name notepad).id
# Construct the named pipe's name
$pipename = -join('named-pipe-',$bosspid)
$fullpipename = -join("\\.\pipe\", $pipename) # fix SO highlighting: "
# This will run in a separate thread
$asyncloop = {
param($pipename, $bosspid)
# Create the named pipe
$pipe = new-object System.IO.Pipes.NamedPipeServerStream($pipename)
# The core loop
while($true) {
$pipe.WaitForConnection()
# The specific signal I'm using to let the loop continue is
# echo m > %pipename%
# in CMD. Powershell's echo will *not* work. Anything other than m
# will trigger the exit condition.
if ($pipe.ReadByte() -ne 109) {
break
}
$pipe.Disconnect()
# (The action this loop is supposed to perform on trigger goes here)
}
$pipe.Dispose()
}
# Set up the exit sequence
$bossproc = Get-Process -pid $bosspid -ErrorAction SilentlyContinue
$exitsequence = {
# While PS's echo doesn't work for passing messages, it does
# open and close the pipe which is enough to trigger the exit condition.
&{echo q > $fullpipename} 2> $null
[Environment]::Exit(0)
}
if ((-Not $bossproc) -or $bossproc.HasExited) { $exitsequence.Invoke() }
# Begin watching for events until boss closes
Start-Job -ScriptBlock $asyncloop -Name "miniloop" -ArgumentList $pipename,$bosspid
while($true) {
Start-Sleep 1
if ($bossproc.HasExited) { $exitsequence.Invoke() }
}
該代碼現在可以正常工作,並且可以完成我需要的工作。
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