如何仅在 PowerShell 中的变量中捕获错误输出

Question

我想将 PowerShell 命令的 stderr 输出存储在变量中。我不想将其存储在文件中，也不希望包含标准输出，只想包含错误输出。

这会重定向到名为

error.txt

:

的文件

& $command $params 2> error.txt

这会将 stderr 和 stdout 重定向到 $output 变量：

$输出=&$命令$参数2>&1

但我只想将错误输出存储在变量中（与上面 error.txt 文件的内容相同），而不向文件写入任何内容。我该怎么做？

Answer 1

-ErrorVariable

参数：

Invoke-Expression "$command $params" -ErrorVariable badoutput

$badoutput

现在将包含错误字符串的内容。

Answer 2

Simon Wahlin

使用子表达式的更简单的解决方案

$输出=&$命令$参数2>&1

将是：

$errOutput = $( $output = & $command $params ) 2>&1

Answer 3

$badoutput[0].Exception

获取。

-ErrorAction 和 -ErrorVariable 有关如何有效使用 PowerShell 中内置的 ErrorAction 和 ErrorVariable 参数的更多信息。 这是展示此功能的最简单方法：

PS> Stop-Process 13,23
Stop-Process : Cannot find a process with the process identifier 13.
At line:1 char:13
+ Stop-Process  <<<< 13,23
Stop-Process : Cannot find a process with the process identifier 23.
At line:1 char:13
+ Stop-Process  <<<< 13,23

PS> Stop-Process 13,23 -ErrorAction Stop  # Only 1 error
Stop-Process : Command execution stopped because the shell variable “ErrorA
ctionPreference” is set to Stop: Cannot find a process with the process ide
ntifier 13.
At line:1 char:13
+ Stop-Process  <<<< 13,23 -ErrorAction Stop  # Only 1 error

PS> Stop-Process 13,23 -ErrorAction silentlycontinue  # No errors

PS> Stop-Process 13,23 -ErrorAction inquire  # ASK
Confirm
Cannot find a process with the process identifier 13.
[Y] Yes  [A] Yes to All  [H] Halt Command  [S] Suspend  [?] Help
(default is “Y”):h
Stop-Process : Command execution stopped because the user selected the Halt
 option.
At line:1 char:13
+ Stop-Process  <<<< 13,23 -ErrorAction inquire  # ASK
PS>
PS>
PS> Stop-Process 13,23 -ErrorVariable a -ErrorAction SilentlyContinue

PS> $a[0]
Stop-Process : Cannot find a process with the process identifier 13.
At line:1 char:13
+ Stop-Process  <<<< 13,23 -ErrorVariable a -ErrorAction SilentlyContinue

PS> $a[0] |fl * -Force

Exception             : Microsoft.PowerShell.Commands.ProcessCommandExcepti
                        on: Cannot find a process with the process identifi
                        er 13.
TargetObject          : 13
CategoryInfo          : ObjectNotFound: (13:Int32) [Stop-Process], ProcessC
                        ommandException
FullyQualifiedErrorId : NoProcessFoundForGivenId,Microsoft.PowerShell.Comma
                        nds.StopProcessCommand
ErrorDetails          :
InvocationInfo        : System.Management.Automation.InvocationInfo

PS> $a |ft TargetObject -force -auto
TargetObject
————
          13
          23

现在人们不明显的一件事是，您可以在 ErrorVariable 的变量名前面指定一个“+”，我们会将错误添加到该变量中。

PS> $err=@()
PS> stop-process 13 -ea silentlycontinue -ErrorVariable err
PS> $err.count
1

PS> stop-process 23 -ea silentlycontinue -ErrorVariable +err
PS> $err.count
2
PS> $err
Stop-Process : Cannot find a process with the process identifier 13.
At line:1 char:13
+ stop-process  <<<< 13 -ea silentlycontinue -ErrorVariable err
Stop-Process : Cannot find a process with the process identifier 23.
At line:1 char:13
+ stop-process  <<<< 23 -ea silentlycontinue -ErrorVariable +err

最后，您不需要输入 –ErrorAction 或 –ErrorVariable，我们已经为这些定义了参数别名，因此您只需输入 

–EA

和

-EV

。

Answer 4

Linux + PowerShell 7.2.16、PowerShell 7.3.2

PS> $s={ 
  /bin/echo "Hello"
  /bin/ls "/errortext"
  Write-Error "Booo"
  Write-Host "Bello"
  Write-Output "World" 
}
PS> $err456 = (Invoke-Command -ScriptBlock $s `
  -OutVariable out123 `
  -ErrorVariable err123 `
  1>$null ) 2>&1
Bello
PS> $out123
Hello
World
PS> $err123

Write-Error: Booo
PS> $err456
/bin/ls: cannot access '/errortext': No such file or directory
Write-Error: Booo