How to navigate in a PowerShell provider without a PSDrive

Here’s an interesting PowerShell trick that I hadn’t come across before.  I may be mistaken, but I don’t believe this is documented anywhere either.

In PowerShell, you can create PowerShell drives (PSDrives) to provide you with fast access to specific locations in the PowerShell providers that you are using.  That is very convenient, but if you are writing scripts that use the drives you create and that you share with others, you need to make sure the PSDrive is created for your script to work.  Or do you?

In PowerShell, you can set the current location to any location on a provider using the following syntax:

Set-Location PSDriveName:RelativePath

In this syntax, RelativePath refers to the path relative to the root of the PSDrive identified by PSDriveName.

Alternatively, you can also set the current location to any location on a provider using the following syntax:

Set-Location PSProviderName::AbsolutePath

In this syntax, AbsolutePath refers to the absolute path to the location on the respective drive (which includes the root if necessary) and PSProviderName refers to the name of the provider, with or without the PowerShell snapin name prefix.

Let’s look at a few specific examples.

If you wanted to set the current location to C:\Windows, you could do any of the following:

1. Set-Location C:\Windows
2. Set-Location FileSystem::C:\Windows
3. Set-Location `
      Microsoft.PowerShell.Core\FileSystem::C:\Windows

How about the registry?  Lets say you wanted to browse HKEY_USERS in your registry so that you could work with the default user configuration.  To do this, you would have to do any of the following:

1. New-PSDrive HKU Registry HKEY_USERS
   Set-Location HKU:\.DEFAULT
2. Set-Location Registry::HKEY_USERS\.Default
3. Set-Location `
      Microsoft.PowerShell.Core\Registry::HKEY_USERS\.Default

What if you wanted to view the root of the registry?  I have no idea how to do that using a PSDrive, but you can do it using the provider path like this:

Set-Location Registry::

The syntax looks a little unusual, but it can be useful.  Executing Get-ChildItem from there gives you all of the hives that are available in the registry.  If you want to do a search across an entire registry, this seems to be the right place to start.

So far all of these examples have been for the providers that are included in the PowerShell 1.0 RTM release.  But the syntax described above works for providers from registered snapins as well.  Using the IIS 7.0 PowerShell Provider Tech Preview 1 we can do the same sort of thing.  For example, I can browse the application pools like this:

Set-Location `
   WebAdministration::\\POSHOHOLIC\AppPools

Note that in this example, POSHOHOLIC is the name of the computer (and it must be in uppercase for it to work in Tech Preview 1 of this provider).  And yes, I could have used IIsProviderSnapin\WebAdministration for the provider name here as well.

One last example from a registered snapin is from the SQL Server 2008 CTP.  You can navigate to the root of this provider like this:

Set-Location SqlServer::SQLSERVER:

This puts you in the same location as if you set the location to SQLSERVER:.  Note again, in this example, the second SQLSERVER must be in uppercase for it to work in the February 2008 CTP version of this provider.  And the syntax here is a little odd as well…the second SQLSERVER really shouldn’t be necessary IMHO.  But it’s there, so we have to use it.

I should also mention that these provider-based paths should work wherever you can use a path.  I tested out a few of them and was satisfied enough to feel confident that the paths will work anywhere.

By now you most likely get the idea of this.  You can continue to write your scripts to create PSDrives and access everything by drive name, or you can work directly with the provider-based paths so that you don’t have to create PSDrives and so that you can access provider roots that are otherwise unavailable.

Kirk out.

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