启动过程后作业的脚本块中的代码不执行 [英] Code in Job's Script Block after Start-Process Does not Execute

问题描述

当我使用PowerShell 5.1创建自动化脚本时，遇到一个问题–在作业的脚本块中，启动过程之后的代码将无法执行.这是一个简单的复制程序:

When I create a automation script with PowerShell 5.1, I got an issue – in a script block of a job, the code after Start-Process will not get chance to execute. Here’s a simple repro:

步骤1 >>为启动过程准备一个.cmd文件，callee.cmd中的代码为:

@echo off
echo "Callee is executing ..."
exit /B 0

步骤2 >>准备PowerShell代码

$scriptBlock = {
    $res = Start-Process -FilePath "cmd.exe" -Wait -PassThru -NoNewWindow -ArgumentList "/c .\callee.cmd"
    throw "ERROR!"
}

$job = Start-Job -ScriptBlock $scriptBlock
Wait-Job $job
Receive-Job $job
Write-Host($job.State)

步骤3 >>运行PowerShell脚本，屏幕上的输出为:

Id     Name            PSJobTypeName   State         HasMoreData     Location             Command
--     ----            -------------   -----         -----------     --------             -------
1      Job1            BackgroundJob   Completed     True            localhost            ...
Completed

期望值应为失败". 我的代码有问题还是我以错误的方式使用作业?

The expected value should be "Failed". Does my code have problem or I’m using jobs in a wrong way?

推荐答案

Start-Job在单独的PowerShell进程中以所谓的服务器模式运行作业.在这种模式下，PowerShell作业流程使用标准的输入和输出流与父流程交换消息.

Start-Job run job in separate PowerShell process in so-called server mode. In this mode PowerShell job process use standard input and output streams to exchange messages with the parent process.

-NoNewWindow参数指示它将生成的控制台子进程连接到其父级的标准流.

-NoNewWindow parameter of Start-Process cmdlet instruct it to connect spawned console child process to the standard streams of its parent.

因此，使用PowerShell作业内部的Start-Process -NoNewWindow，将生成的cmd.exe进程连接到相同的流，PowerShell作业进程使用该流与自己的父进程交换消息.

Thus, using Start-Process -NoNewWindow inside of PowerShell job, you connect spawned cmd.exe process to the same streams, which PowerShell job process use to exchange messages with its own parent process.

现在，生成cmd.exe到其标准输出流中时，它会扰乱PowerShell作业进程与其父进程之间的正常消息交换，从而导致某些意外行为.

Now, when spawned cmd.exe write something into its standard output stream, it disturb normal message exchange between PowerShell job process and its parent, which leads to some unexpected behavior.

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