powershell - 无法将参数绑定(bind)到参数 'command'，因为它为空。电源外壳

Question

我有一个类似于下面代码的功能。它接收命令和命令参数。我必须在后台运行这个命令并收集输出。但是最后一条语句让我犯了这个错误

错误:

Cannot bind argument to parameter 'Command' because it is null.
+ CategoryInfo          : InvalidData: (:) [Invoke-Expression], ParameterBindingValidationException
+ FullyQualifiedErrorId : ParameterArgumentValidationErrorNullNotAllowed,Microsoft.PowerShell.Commands.InvokeExpre
ssionCommand
+ PSComputerName        : localhost

代码:

$cmd = 'Get-content'
$Arg = 'path to file'
$sb = "$cmd $Arg -ErrorVariable e -ErrorAction Stop"
invoke-Expression $sb #This printsoutput
$job = Start-job -ScriptBlock {Invoke-Expression $sb}
wait-job -id $job.Id
$job | Receive-job #this should print output but throwing error

我很确定最后一行是抛出错误的那一行。

Answer 1

获得 $sb 的另一种选择除了 -argumentlist 之外的脚本 block 的范围内是使用$using:范围。 (PowerShell 3+)

$cmd = 'Get-content'
$Arg = 'path to file'
$sb = "$cmd $Arg -ErrorVariable e -ErrorAction Stop"
$job = Start-job -ScriptBlock {Invoke-Expression $using:sb}
wait-job -id $job.Id
$job | Receive-job