Powershell:使用带有字符串的 Select-Object 表达式 [英] Powershell : Use a Select-Object expression with a string

问题描述

对于某些脚本，我需要有一个由计算属性组成的输出.

For some scripts, i need to have an output composed of calculated properties.

例如，对于 ip.txt 中的 ip 地址列表，我想知道它们是否响应 ping.所以我尝试以下命令:

For example, for a list of ip addresses in ip.txt, i want to know if they respond to ping. So i try the following command:

Get-Content .\ip.txt | Select-Object $_,@{Name="ping?";Expression={Test-Connection $_ -Quiet -Count 1}}

但是我得到一个错误，不管我在脚本块表达式中做什么.

But i get an error, regardless of what i do in the scriptblock expression.

错误(法语，抱歉):

<代码>选择对象:参数空.请键入参加者doit être l'un des suivants:{System.String, System.Management.Automation.ScriptBlock}.Au niveau de ligne : 1 Caractère : 37+ 获取内容 .\ip.txt |选择对象<<<<<$_,@{Name="ping?";Expression={Test-Connection $_ -Quiet -Count 1}}+ CategoryInfo : InvalidArgument: (:) [Select-Object], NotSupportedException+ FullQualifiedErrorId : DictionaryKeyUnknownType,Microsoft.PowerShell.Commands.SelectObjectCommand

我之前在一些脚本中使用了计算属性"，但使用了目录对象.为什么它不适用于字符串?

I used the "calculated properties" in some scripts before, but with directories objects. Why it doesnt work with strings?

推荐答案

试试这个，你需要为每个值创建计算属性:

try this instead, you need to create calculated properties for each value:

Get-Content .\ip.txt | Select-Object  @{n="Server IP";e={$_}},@{n="ping?";e={[bool](Test-Connection $_ -Quiet -Count 1)}}

您代码中的问题是 $_ 不是计算属性.Select-object 接受和属性数组，如果在您传递的数组中 $_ 不被评估为属性.如果你只做 select-object $_ (如 select-object -prop $null )管道项目是输出.

The problem in your code is the $_ not the calculated property. Select-object accept and array of properties, if in the array you pass $_ isn't evaluated as a property. If you do just select-object $_ (as select-object -prop $null ) piped items are the output.

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