PowerShell 2.0以及如何处理异常？ [英] PowerShell 2.0 and how to handle exceptions?

问题描述

为什么在运行这两个简单的样本时会在控制台上打印出错误信息？
我想要在控制台上打印出我的错误测试:)：

Get-WmiObject：RPC服务器是
不可用。 （HRESULT的异常：
0x800706BA）在行：3 char：15
+ Get-WmiObject<<<< -ComputerName might.nonexisting.domain.com
-Credential（Get-Credential） - 类Win32_logicaldisk
+ CategoryInfo：InvalidOperation：（:) [Get-WmiObject]，
COMException
+ FullyQualifiedErrorId：GetWMICOMException，Microsoft.PowerShell.Commands.GetWmiObjectCommand

或

尝试除以零。在行：3
char：13
+ $ i = 1 /<<<< 0

+ CategoryInfo：NotSpecified：（:) []，
ParentContainsErrorRecordException
+ FullyQualifiedErrorId：RuntimeException

第一个例子：

  try 
 {
 $ i = 1/0 
写主机$ i 
} 
 catch [异常] 
 {
写主机错误测试:)
} 
  

第二个例子：

  try 
 {
 Get-WmiObject -ComputerName might.nonexisting.domain.com -Credential（Get-Credential）-Class Win32_logicaldisk 
} 
 catch [Exception] 
 {
写主机错误测试:)
} 
  

非常感谢

解决方案

第一个例子

<在编译/解析时出现错误（PowerShell足够聪明），因此代码甚至不执行，也无法捕获任何东西。尝试这个代码，你会得到一个例外：

  try 
 {
 $ x = 0 
 $ i = 1 / $ x 
写主机$ i 
} 
 catch [异常] 
 {
写主机错误测试:) 
} 
  

---

第二个例子

如果您在全局设置 $ ErrorActionPreference ='Stop'，那么您将获得错误测试： ）按预期印刷。但是你的 $ ErrorActionPreference 可能是'继续'：在这种情况下，没有终止错误/异常，你只是得到

而不是全局 $ ErrorActionPreference 选项，您可以还可以使用 Get-WmiObject 参数 ErrorAction 。尝试将其设置为停止，您将收到一个例外。

 尝试
 {
 Get-WmiObject -ErrorAction Stop -ComputerName possible.nonexisting.domain.com -Credential（Get-Credential） - 类Win32_logicaldisk 
} 
 catch [Exception] 
 {
写主机错误测试:)
} 
  

Why I get error message printed on the console when running these two simple samples ? I want that I get "Error testing :)" printed on the console insted of:

Get-WmiObject : The RPC server is unavailable. (Exception from HRESULT: 0x800706BA) At line:3 char:15 + Get-WmiObject <<<< -ComputerName possibly.nonexisting.domain.com -Credential (Get-Credential) -Class Win32_logicaldisk + CategoryInfo : InvalidOperation: (:) [Get-WmiObject], COMException + FullyQualifiedErrorId : GetWMICOMException,Microsoft.PowerShell.Commands.GetWmiObjectCommand

or

Attempted to divide by zero. At line:3 char:13 + $i = 1/ <<<< 0
+ CategoryInfo : NotSpecified: (:) [], ParentContainsErrorRecordException + FullyQualifiedErrorId : RuntimeException

First example:

try
{
    $i = 1/0   
    Write-Host $i     
}
catch [Exception]
{ 
    Write-Host "Error testing :)" 
}

Second example:

try
{
    Get-WmiObject -ComputerName possibly.nonexisting.domain.com -Credential (Get-Credential) -Class Win32_logicaldisk 
}
catch [Exception]
{ 
    Write-Host "Error testing :)" 
}

Thank you very much!

解决方案

First example

The error happens at compile/parsing time (PowerShell is clever enough), so that the code is not even executed and it cannot catch anything, indeed. Try this code instead and you will catch an exception:

try
{
    $x = 0
    $i = 1/$x
    Write-Host $i
}
catch [Exception]
{
    Write-Host "Error testing :)"
}

---

Second example

If you set $ErrorActionPreference = 'Stop' globally then you will get "Error testing :)" printed, as expected. But your $ErrorActionPreference is presumably 'Continue': in that case there is no terminating error/exception and you just get the non terminating error message printed to the host by the engine.

Instead of the global $ErrorActionPreference option you can also play with Get-WmiObject parameter ErrorAction. Try to set it to Stop and you will catch an exception.

try
{
    Get-WmiObject -ErrorAction Stop -ComputerName possibly.nonexisting.domain.com -Credential (Get-Credential) -Class Win32_logicaldisk
}
catch [Exception]
{
    Write-Host "Error testing :)"
}

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