如何获得“调用表达式"的状态，成功还是失败? [英] How to get status of "Invoke-Expression", successful or failed?

问题描述

Invoke-Expression 将返回被调用命令的所有文本.

Invoke-Expression will return all the text of the command being invoked.

但是我怎样才能得到这个命令是成功执行还是失败的系统返回值呢?在 CMD 中，我可以使用 %errorlevel% 来获取外部命令执行状态.PowerShell 怎么样?

But how can I get the system return value of whether this command has been executed successfully or with a failure? In CMD I could use %errorlevel% to get external command execution state. What about PowerShell?

推荐答案

通常你会使用 $? 来检查最后执行的语句的状态:

Normally you would use $? to inspect the status of the last statement executed:

PS C:\> Write-Output 123 | Out-Null; $?
True
PS C:\> Non-ExistingCmdlet 123 | Out-Null; $?
False

但是，这不适用于 Invoke-Expression，因为即使传递给 Invoke-Expression 的表达式中的语句可能会失败，Invoke-Expression 调用它自己会成功(即表达式，尽管无效/非功能性被调用)

However, this won't work with Invoke-Expression, because even though a statement inside the expression passed to Invoke-Expression may fail, the Invoke-Expression call it self will have succeeded (ie. the expression, although invalid/non-functional was invoked none the less)

使用 Invoke-Expression 你必须使用 try:

With Invoke-Expression you'll have to use try:

try {
    Invoke-Expression "Do-ErrorProneAction -Parameter $argument"
} catch {
    # error handling go here, $_ contains the error record
}

或陷阱:

trap {
    # error handling goes here, $_ contains the error record
}
Invoke-Expression "More-ErrorProneActions"

<小时>

另一种方法是将 ";$?" 附加到要调用的表达式中:

---

The alternative is the append ";$?" to the expression you want to invoke:

$Expr  = "Write-Host $SomeValue"
$Expr += ';$?'

$Success = Invoke-Expression $Expr
if(-not $Success){
    # seems to have failed
}

但依赖于没有任何管道输出

but relies on there not being any pipeline output

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