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Accepted
ConfusedButterfly
Asked: 2024-11-19 15:32:42 +0800 CST

在 if 语句中使用函数时出现意外的返回值[重复]

  • 772
$PSVersionTable.PSVersion

Major  Minor  Build  Revision
-----  -----  -----  --------
5      1      22621  4391

考虑以下代码片段

# Function to determine if the OS is Windows Server
function Is-WindowsServer {
    $osVersion = (Get-WmiObject -Class Win32_OperatingSystem).Caption
    return $osVersion -like "*Server*"
}

# Function to check if SMB/Network Sharing is installed
function Is-SMBInstalled {
    if (Is-WindowsServer) {
        Write-Output "Detected Windows Server. This should print."
        $smbFeature = Get-WindowsFeature -Name FS-SMB1 -ErrorAction SilentlyContinue
        if ($smbFeature -and $smbFeature.Installed) {
            return $true
        } else {
            return $false
        }
    } else {
        Write-Output "Detected Windows 10/11 client. This should print."
        $smbFeature = Get-WindowsOptionalFeature -Online -FeatureName "SMB1Protocol" -ErrorAction SilentlyContinue
        if ($smbFeature -and $smbFeature.State -eq "Enabled") {
            return $true
        } else {
            return $false
        }
    }
    Write-Output "This should be unreachable."
}

Is-SMBInstalled # probe

if (Is-SMBInstalled -eq $true) {
    Write-Output "If above line is False. This should not print."
}

在禁用 Samba 的 Windows 10/11 上的预期输出：

Detected Windows 10/11 client. This should print.
False

禁用 Samba 的 Windows 10/11 上的脚本输出：

Detected Windows 10/11 client.
False
If above line is False. This should not print.

此外，就其本身而言，

if (Is-SMBInstalled -eq $true) {
    Write-Output "If above line is False. This should not print."
}

似乎无法正确调用 Is-SMBInstalled。如果没有Is-SMBInstalled # probe，输出只是If above line is False. This should not print.

我尝试过将 Is-SMBInstalled 放入 $variable 中进行重构，这在某种意义上是有效的，因为该函数被正确调用。但条件仍然表现异常。

我也尝试了按照https://stackoverflow.com/a/66585435/14097947 if ((Is-SMBInstalled)) {的分组功能，但这也不起作用。

powershell

1 个回答

  1. Best Answer

    通过使用Write-Output的结果Is-SMBInstalled始终是一个混合内容数组，因为Write-Output将其内容推送到成功流（又名 stdOut）与相同Return。

    因此，与左侧相比，其始终为真。

    Write-Output用替换Write-Host，这样就不会在成功流中写入。

    既然您已经在那里：

    1. 替换Get-WimObject为Get-CimInstance：这些Wimcmdlet 自 Powershell 3 以来已过时，并且已从 powershell 6+ 中删除。
      这样做将使其向前兼容。
    2. 我建议使用已批准的动词。

    有一个例子

    # Function to determine if the OS is Windows Server
function Test-IsWindowsServer {
    # Left-side Filtering for the win.   
    # It returns $False if it finds nothing, and $True if it finds anything.   
    # NOTE WELL: I don't have Windows Server available to test now, so check if
    # the filter is working correctly.   
    [bool](Get-CimInstance -ClassName Win32_OperatingSystem -Filter 'Caption Like "%server%"')
}

# Function to check if SMB/Network Sharing is installed
function Test-IsSMBInstalled {
        
    if (Test-IsWindowsServer) {
        Write-Host 'Detected Windows Server. This should print.'
        $smbFeature = Get-WindowsFeature -Name FS-SMB1 -ErrorAction SilentlyContinue

        # no reason for a IF, this will return either $true or $False directly.   
        return ($smbFeature.Installed) 
    }
    # Strictly speaking you don't need the Else because it's not reaching here
    # if Test-IsWindowsServer is $true, evaluate yourself if it's clearer with
    # or without.   
    else {
        Write-Host 'Detected Windows 10/11 client. This should print.'
        $smbFeature = Get-WindowsOptionalFeature -Online -FeatureName 'SMB1Protocol' -ErrorAction SilentlyContinue 
        
        # no reason for a IF, this will return either $true or $False directly.   
        # Evaluate using "-like" instead of "-eq".  
        return ($smbFeature.State -eq 'Enabled') 
    }

    # A Write-Warning is the perfect fit for this.   
    Write-Warning 'This should be unreachable.'
}

# This will print the 'Detected' version line and then the boolean output.   
Test-IsSMBInstalled

# note this will print again the 'Detected' version line.   
if (Test-IsSMBInstalled) {  
    Write-Host 'If above line is False. This should not print.'
}
    • 4

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