How to make @'...'@ work in powershell.exe -command ""?

Question

Background

This is a PowerShell script for refreshing Internet proxy settings which I got from Batch File to disable internet options proxy server.

function Refresh-System {
    $signature = @'
[DllImport("wininet.dll", SetLastError = true, CharSet=CharSet.Auto)]
public static extern bool InternetSetOption(IntPtr hInternet, int dwOption, IntPtr lpBuffer, int dwBufferLength);
'@

    $INTERNET_OPTION_SETTINGS_CHANGED   = 39
    $INTERNET_OPTION_REFRESH            = 37
    $type = Add-Type -MemberDefinition $signature -Name wininet -Namespace pinvoke -PassThru
    $a = $type::InternetSetOption(0, $INTERNET_OPTION_SETTINGS_CHANGED, 0, 0)
    $b = $type::InternetSetOption(0, $INTERNET_OPTION_REFRESH, 0, 0)
    return $a -and $b
}
Refresh-System

Problem

I want to run it in batch file or command prompt as a single command such as

powershell.exe -Command "stmnt1; stmnt2; ..."

Which I learned from How to condense PowerShell script to fit on a single line.

Approach

I've tried to combine it altogether into one line and execute it.

powershell -command "$signature = @'[DllImport("wininet.dll", SetLastError = true, CharSet=CharSet.Auto)] public static extern bool InternetSetOption(IntPtr hInternet, int dwOption, IntPtr lpBuffer, int dwBufferLength)'@; $INTERNET_OPTION_SETTINGS_CHANGED   = 39; $INTERNET_OPTION_REFRESH            = 37; $type = Add-Type -MemberDefinition $signature -Name wininet -Namespace pinvoke -PassThru; $a = $type::InternetSetOption(0, $INTERNET_OPTION_SETTINGS_CHANGED, 0, 0); $b = $type::InternetSetOption(0, $INTERNET_OPTION_REFRESH, 0, 0);"

But it returned me an error.

At line:1 char:16
+ $signature = @'[DllImport(wininet.dll, SetLastError = true, CharSet=C ...
+                ~
No characters are allowed after a here-string header but before the end
of the line.
    + CategoryInfo          : ParserError: (:) [], ParentContainsErrorRecordException
    + FullyQualifiedErrorId : UnexpectedCharactersAfterHereStringHeader

Question

How do I solve it? Is there any better ways to condense the function above?

Answer 1

The @ characters around the $signature variable are what's known as a Here-String and are explicitly intended for blocks of text that may include new lines.

The signature definition is just C# code and that particular code snippet doesn't actually need the included line breaks to function. So can just declare it like a regular string instead.

$signature = '[DllImport("wininet.dll", SetLastError = true, CharSet=CharSet.Auto)] public static extern bool InternetSetOption(IntPtr hInternet, int dwOption, IntPtr lpBuffer, int dwBufferLength);'

However, you're also going to have to deal with escaping the embedded double quotes which according to the "Calling PowerShell's CLI from cmd.exe or POSIX-like shells" section of this answer means you should replace each of them with "^""

Is there a particular reason the PowerShell code has to be embedded in the batch file rather than its own .ps1 file along side it that your batch file references? Because that's the least hassle if you can manage it.

Your other option instead of having to one-line'ify and escape the PowerShell code is to use PowerShell's ability to run a Base64 encoded script via the -EncodedCommand parameter. Assuming you have your Refresh-System.ps1 script already, you could do something like this to generate the batch file.

$scriptText = Get-Content .\Refresh-System.ps1 -Raw
$scriptB64 = [Convert]::ToBase64String([Text.Encoding]::Unicode.GetBytes($scriptText))
"powershell.exe -EncodedCommand `"$scriptB64`"" | Out-File refresh-system.cmd -Encoding ascii