我有一个简单的Powershell脚本,我在Powershell ISE中写道。它的主旨在于它将一个命名管道作为执行动作的信号来监视,同时监视其老板进程。当boss-process退出时,脚本也会退出。简单。
在努力让命名管道在Powershell中工作而不崩溃之后,我设法获得了工作代码,如下所示。然而,虽然这在Powershell ISE和交互式终端中运行良好,但我却无法将其作为一个独立的脚本工作。
$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)
第一个问题是脚本在执行任何有意义的操作之前终止。但是延迟执行的结束,例如while($true)
循环,-NoExit
标志,pause
命令,或者甚至是为此目的而制作的特定命令,如Wait-Event
,将导致进程保持开放,但仍然不会使它响应事件。
我放弃了以“正确”的方式做到这一点,而是恢复使用包含在while-true块和Job控件中的同步代码。
$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() }
}
这段代码现在运行得很好,完成了我需要的工作。