How to run appCmd in PowerShell to add custom headers to the Default Web Site

Question

Please help me figure out how to properly escape the arguments so they work when calling appcmd inside of powershell.

My script looks like this:

$defaultWebSite = "Default Web Site"
$appCmd = "C:\windows\system32\inetsrv\appcmd.exe"
$addHeaderP3P = "set config ""$defaultWebSite"" -section:system.webServer/httpProtocol /+""customHeaders.[name='P3P',value='policyRef=`\`"/w3c/p3p.xml`\`",CP=`\`"DSP COR NID OUR COM PRE`\`"']`""

Write-Output "Here's the argument string: " $addHeaderP3P



Write-Output "`nInvoke Result:"
Invoke-Expression "$appCmd $addHeaderP3P"


Write-Output "`n& Result:"
& $appCmd --%"$addHeaderP3P"

The output is this when running inside powershell_ise:

PS C:\Users\robert.bratton> D:\Junk\p3pheader.ps1
Here's the argument string: 
set config "Default Web Site" -section:system.webServer/httpProtocol /+"customHeaders.[name='P3P',value='policyRef=\"/w3c/p3p.xml\",CP=\"DSP COR NID OUR COM PRE\"']"

Invoke Result:
Failed to process input: The parameter 'COR' must begin with a / or - (HRESULT=80070057).


& Result:
Failed to process input: The parameter 'NID' must begin with a / or - (HRESULT=80070057).

This works from the command line

"C:\windows\system32\inetsrv\appcmd.exe" set config "Default Web Site" -section:system.webServer/httpProtocol /+"customHeaders.[name='P3P',value='policyRef=\"/w3c/p3p.xml\",CP=\"DSP COR NID OUR COM PRE\"']"

Thanks for your help!

Solution

Try it like this:

$env:defaultWebSite = "Default Web Site"
$appCmd = "C:\windows\system32\inetsrv\appcmd.exe"

& $appCmd --% set config "%defaultWebSite%" -section:system.webServer/httpProtocol /+customHeaders.[name='P3P',value='policyRef="/w3c/p3p.xml",CP="DSP COR NID OUR COM PRE"']

If you use any variables after the --% the have to be environment variables.

Comments

[Robert Bratton]

Thanks for the suggestion. I get an error about a missing close quote. The string starting: At line:4 char:180 + & $appCmd --% set config "%defaultWebSite%" -section:system.webServer/httpProtocol /+""customHeaders.[name='P3P',value='policyRef=\"/w3c/p3p.xm‌​l\",CP=\"DSP COR NID OUR COM PRE\"'] <<<< " is missing the terminator: ". At line:4 char:181

[Keith Hill]

I copied everything from -section to the end from the example you listed above as working. However you may have made changes to make that work from PowerShell. At the point you specify --% PowerShell parses more like cmd.exe. Let me take a crack to getting rid of the PowerShell workarounds.