Category: Powershell

Stuart Moore shows an easy way to execute a Powershell script against multiple servers:

We setup new PsSessions using New-PsSession, I set ErrorAction to SilentlyContinue just in case a host isn’t available for some reason (if I was being good I’d try/catch here).

As we’re just using PS standard functionality here with Get-Service there’s no need to build a a new function, we can just call this directly here. By calling Invoke-Command against a session pointed at numerous hosts we can PowerShell handle all the connection management here and just assume the command will be ran against each host. if we were running against a lot of hosts then we would want to look into using the -ThrottleLimit parameter to limit the number of concurrent hosts we’re hitting. The one little trick here is using the using scope modifier here so PS pulls in the variable defined in our main scope (gory details on scoping here

Click through for the script, and do check out the comments, where Stuart gives a bit of advice when you’re trying to execute against a large number of servers.

Viorel Ciucu has a Powershell script using dbatools to configure a new SQL Server instance and migrate databases using TDE over to the new instance:

The second option (and the one we chose) was to leave the encryption enabled. In order to be able to attach the files, or to do restores from the backups you need to have the same certificate that was used for encryption. This certificate is protected by the master key.

To accomplish this:

1. Make backups of the master key and the certificates

2. Restore the key and certificates on the new principal and mirror pairs

Read on for the process.

Rob Sewell shows you how to implement Confirm, Verbose, and WhatIf parameters in Powershell cmdlets:

I have done this before because if the file does not exist then Set-Content will create a new file for you, but with this function I can check if the file exists first with the ValidateScript before running the rest of the function.

As you can see I add variables from my PowerShell code into the “The Item” and “The Change”. If I need to add a property of an object I use $($Item.Property).

So now, if I want to see what my new function would do if I ran it without actually making any changes I have -WhatIf added to my function automagically.

It’s easy to do and makes your code that much better.

Rob Sewell describes a class of Powershell parameters designed to keep you from doing something awful on accident:

If you wanted to see what would happen, you could edit the script and add the WhatIf parameter to every changing command but that’s not really a viable solution. What you can do is

1	$PSDefaultParameterValues[‘*:WhatIf’] = $true

this will set all commands that accept WhatIf to use the WhatIf parameter. This means that if you are using functions that you have written internally you must ensure that you write your functions to use the common parameters

Once you have set the default value for WhatIf as above, you can simply call your script and see the WhatIf output

WhatIf is a great parameter and when developing cmdlets, you should add in support.