PowerShell中echo和Write-Host有什么区别？

Question

我对PowerShell echo和Write-HostPowerShell 之间的区别感到困惑.我有两个文件,POC.ps1&validatePath.ps1.这些文件在我的本地计算机上,我正在使用远程计算机上运行它们Invoke-Command.我使用的是PowerShell v3.0.

要执行这两个脚本,我使用命令:

.\POC.ps1 -filename C:\Users  -user Blaine

这是两个文件:

POC.ps1:

param($filename, $user)

echo $filename
echo "This"
echo $user

$responseObject = Invoke-Command testcomputer -FilePath .\validatePath.ps1  -ArgumentList($filename, $user) -AsJob

while($responseObject.State -ne "Completed")
{

}

$result = Receive-Job -Id $responseObject.Id -Keep
echo $result

这是事情变得奇怪的地方......

validatePath.ps1:

Param([string] $filename,
      [string] $user)

function ValidatePath( $filename, $user, $fileType = "container" )
{
    Write-Host "This is the file name: $filename"
    Write-Host "This is user: $user"  <--- Notice I'm using Write-Host here
    $fileExist = $null
    if( -not (test-path $filename -PathType $fileType) )
    {
        throw "$user, the path $filename does not exist!"

    }
    else
    {
         Write-Host "This is the second part"
         echo $filename found!
    }
    Write-Host "This is the third part"
    return $fileExist
}


try
{

    ValidatePath($filename, $user)
}
catch
{
    $e = $_.Exception
    echo $e
}

当我运行上面的脚本时,这是输出:

C:\Users
This
Blaine
This is the file name: C:\Users Blaine
This is user:  <--- Notice where this line is?
This is the second part
This is the third part
C:\Users
Blaine
found!

但如果我改变了validatePath.ps1这个:

Param([string] $filename,
      [string] $user)

function ValidatePath( $filename, $user, $fileType = "container" )
{
    Write-Host "This is the file name: $filename"
    echo "This is user: $user" <---notice I'm using Echo here
    $fileExist = $null
    if( -not (test-path $filename -PathType $fileType) )
    {
        throw "$user, the path $filename does not exist!"

    }
    else
    {
         Write-Host "This is the second part"
         echo $filename found!
    }
     Write-Host "This is the third part"
    return $fileExist
}


try
{

    ValidatePath($filename, $user)
}
catch
{
    $e = $_.Exception
    echo $e
}

这是输出:

C:\Users
This
Blaine
This is the file name: C:\Users Blaine
This is the second part
This is the third part
This is user: <---- Notice where this line is now?
C:\Users
Blaine
found!

您会注意到"这是用户:"这一行位于不同的位置.为什么是这样？为什么echo工作方式不同Write-Host？

更新:

更奇怪的是,如果我像这样两次重新运行脚本:

POC.ps1:

param($filename, $user)

echo $filename
echo "This"
echo $user

$responseObject = Invoke-Command CAPTESTPK01 -FilePath .\validatePath.ps1  -ArgumentList $filename, $user -AsJob

while($responseObject.State -ne "Completed")
{

}

$result = Receive-Job -Id $responseObject.Id -Keep
echo $result


$filename = "C:\saddfasdfj"

#Here I run the command again, using a different file name
$responseObject = Invoke-Command CAPTESTPK01 -FilePath .\validatePath.ps1  -ArgumentList $filename, $user -AsJob

while($responseObject.State -ne "Completed")
{
   if($responseObject.State -eq "Failed")
   {
        echo "Failed"
        $result = Receive-Job -Id $responseObject.Id -Keep
        echo $result
        break
   }
}

$result = Receive-Job -Id $responseObject.Id -Keep
echo $resul

它使用的时候给我这个输出echo中validatePath.ps1:

C:\Users
This
Blaine
This is the file name: C:\Users
This is the second part
This is the third part
This is user: Blaine <---- This line is here
C:\Users
found!
This is the file name: C:\saddfasdfj
This is user: Blaine <---- But now it's here, where it should be? Wth?
Blaine, the path C:\saddfasdfj does not exist!

Answer 1

echo是别名Write-Output,用于写入Success输出流.这允许通过管道处理输出或重定向到文件.Write-Host直接写入控制台,因此无法进一步重定向/处理输出.

Answer 2

echo是Write-Output的别名.在Write-Host直接写入'screen'的地方,Write-Output写入管道.如果管道没有输入其他命令,它最终也会在"屏幕"上结束.您看到的差异是Write-Host直接写入屏幕,其中Write-Output首先通过管道,并在Write-Host之后在屏幕上结束.

使用Write-Output允许您将输出管道/重定向到文件或另一个命令,而Write-Host则不会.应根据您的需要使用它们.

请看这里了解更多.