powershell 函数返回错误的结果答案

【问题标题】：powershell function return bad resultpowershell 函数返回错误的结果
【发布时间】：2018-10-16 08:29:54
【问题描述】：

我有这个函数，它以另一个用户身份运行命令并返回结果。

$OutputEncoding = [ System.Text.Encoding]::UTF8   
write-host (get-date -format s) " Beginning script..."
function getCreds()
{
    $Username = 'domain\user'
    $Password = 'test'
    $pass = ConvertTo-SecureString -AsPlainText $Password -Force
    $Credential = New-Object System.Management.Automation.PSCredential -ArgumentList $UserName, $pass
    return $Credential;
}
function executeAsCryptUser($cmd){

write-host "cmd:"$cmd
$creds=getCreds
#Use System.Diagnostics to start the process as UserB
$ProcessInfo = New-Object System.Diagnostics.ProcessStartInfo
#With FileName we're basically telling powershell to run another powershell process
$ProcessInfo.FileName = "powershell.exe"
#CreateNoWindow helps avoiding a second window to appear whilst the process runs
$ProcessInfo.CreateNoWindow = $true
#Note the line below contains the Working Directory where the script will start from
$ProcessInfo.WorkingDirectory = $env:windir
$ProcessInfo.RedirectStandardError = $true 
$ProcessInfo.RedirectStandardOutput = $true 
$ProcessInfo.UseShellExecute = $false
#The line below is basically the command you want to run and it's passed as text, as an argument
$ProcessInfo.Arguments = $cmd
#The next 3 lines are the credential for UserB, as you can see, we can't just pass $Credential
$ProcessInfo.Username = $creds.GetNetworkCredential().username
$ProcessInfo.Domain = $creds.GetNetworkCredential().Domain
$ProcessInfo.Password = $creds.Password
#Finally start the process and wait for it to finish
$Process = New-Object System.Diagnostics.Process 
$Process.StartInfo = $ProcessInfo 
$Process.Start() 
$Process.WaitForExit() 
#Grab the output
$GetProcessResult = $Process.StandardOutput.ReadToEnd().ToString()
Write-host "Potential Error:"+ $Process.StandardError.ReadToEnd().ToString()
$result=$GetProcessResult.Trim()
write-Host "Debug output:"$result

return $result
}

$pop=executeAsCryptUser "whoami"
write-host "out:" $pop

当我运行它时，它可以工作，但是我在返回变量中注入了一个“True”。我得到以下输出：

出：真正的域\测试

如果我调试脚本并查看$result 并在变量中找不到“True”的痕迹。

有什么问题？谢谢

【问题讨论】：

标签： windows shell powershell

【解决方案1】：

您的问题是您将两个值写入输出流，该输出流用于在函数之间传输值（沿管道传输）。

值从何而来：

  # Below return "True" to the output-stream
  $Process.Start()
  ...
  # Below appends the content of "result" and return from the function
  return $result

阅读link 关于流的信息。简而言之：命令的每个返回值都会写入输出流，除非您将结果存储在变量中。

我认为你需要改变

$Process.Start()

到

$Process.Start() | Out-Null

上面的行丢弃了True 返回值。作为替代方案，您可以将结果存储在变量中并保持不使用，例如：

$rv = $Process.Start()

另外请注意，PowerShells return 语句具有不同的行为，例如C# 之一。

您的线路：

return $result

相当于：

# Append content to output stream
$result
# return from the function
return

阅读此link 了解有关退货的更多信息。

希望对您有所帮助。

【讨论】：