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Passing parameters to a script block

Passing parameters to a scriptblock seems to be an issue at the moment.

Consider a simple scriptblock

Invoke-Command -ScriptBlock {Get-Process}

How can you modify that to parameterise the processes that are returned.

Its a two step process. Add a parameter block to your script block and secondly pass the correct values to the scriptblock

Invoke-Command -ScriptBlock {
  param ($proc )
  Get-Process -Name $proc
} -ArgumentList "power*"

If you want to pass an array of values to the scriptblock you have 2 options. First abandon the named parameter

$p = ("power*", "win*")

Invoke-Command -ScriptBlock {
  
  Get-Process -Name $args
} -ArgumentList $p

if you use $args then all arguments are available through the array

Scriptblocks unravel the array of arguments so if you want named parameters then you need to force the scriptblock to accept an array by using the unary comma operator

$p = ("power*", "win*")

Invoke-Command -ScriptBlock {
  param ($proc )
   
  Get-Process -Name $proc
} -ArgumentList (,$p)

Generating passwords

Generating new passwords can be a painful business. There are many ways of accomplishing password generation – depending on your needs.  One suggestion for generating passwords is to use a GUID as the basis of the password

PS> New-Guid

Guid 
---- 
269f328d-b80d-446a-a14c-6197ff1bcc40

You could then remove the hyphens and extract part of the guid

PS> (New-Guid).Tostring() -replace '-' 
c5023096aee24b3ba1d9988ff1c774e4

You need to decide the length of the password.  Guids are 32 characters so make sure you start your extraction in a position that gives room for the length you need

$length = 8

((New-Guid).Tostring() -replace '-').Substring((Get-Random -Minimum 0 -Maximum (31-$length)), $length)

Your results will look like these examples

fbe8e66e 
980d4032 
0341d71f 
6f6478fd 
fbfea1ce 
34694bc6 
62666733 
b1419ac0 
3cf8aa7d

The drawback is that you only have numbers and lower case characters

If you use the Membership class from System.Web you can do this

PS> Add-Type -AssemblyName System.Web 
PS> [System.Web.Security.Membership]::GeneratePassword(8,2) 
1L*q381)

The GeneratePassword method takes 2 arguments – the first is the length of the password and the second is the number of non-alphanumeric characters

If you’re running PowerShell v5 you can utilise the using keyword instead of Add-Type

PS> using assembly System.Web 
PS> [System.Web.Security.Membership]::GeneratePassword(8,1) 
f>jg84XR

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Sign up for DoD notifications at https://www.manning.com/dotd

Get-PhysicalDisk options

These are the Get-PhysicalDisk options for identifying the disk you want

-UniqueId <string>

-ObjectId <string>

-FriendlyName <string>

-InputObject <CimInstance#MSFT_PhysicalDisk>

-StorageSubsystem <CimInstance#MSFT_StorageSubsystem>

-StorageEnclosure <CimInstance#MSFT_StorageEnclosure>

-StorageNode <CimInstance#MSFT_StorageNode>

-StoragePool <CimInstance#MSFT_StoragePool>

-VirtualDisk <CimInstance#MSFT_VirtualDisk>

When dealing with disks installed in the machine then the friendly names is the easiest to use

PS> Get-PhysicalDisk | Format-List UniqueId, ObjectId, FriendlyName

UniqueId     : 60022480233DF060FE631B8A4EDD93A0
ObjectId     : {1}\\W510W16\root/Microsoft/Windows/Storage/Providers_v2\SPACES_PhysicalDisk.ObjectId="{1dab9cf6-a1b4-11e6-a890-806e6f6e6963}:PD:{12e941a8-6125-c008-8806-8868642331ef}"
FriendlyName : Msft Virtual Disk

UniqueId     : {d8e80f34-22bc-0a36-b302-d96abe30a6cc}
ObjectId     : {1}\\W510W16\root/Microsoft/Windows/Storage/Providers_v2\SPACES_PhysicalDisk.ObjectId="{1dab9cf6-a1b4-11e6-a890-806e6f6e6963}:PD:{d8e80f34-22bc-0a36-b302-d96abe30a6cc}"
FriendlyName : Samsung SSD 840 PRO Series

String casing

There are times when you may want to change string casing. You have a couple of options.

There are a couple of methods on the string class that you can use to modify the case of a string.

PS> 'aaa'.ToUpper() 
AAA

PS> 'AAA'.ToLower() 
aaa

Alternatively you can use the culture information

PS> (Get-Culture).TextInfo.ToLower('AAA') 
aaa 
 PS> (Get-Culture).TextInfo.ToUpper('aaa') 
 AAA 
 PS> (Get-Culture).TextInfo.ToTitleCase('aaa') 
Aaa

The interesting one is To Titlecase which will capitalise the first letter and make the rest lower case

PS> (Get-Culture).TextInfo.ToTitleCase('aaBaaC') 
Aabaac

At least it does for my culture settings

PS> Get-Culture

LCID             Name             DisplayName 
 ----             ----             ----------- 
 2057             en-GB            English (United Kingdom)

You’ll need to test what it does if you have a different culture setting

Build a better pull server

DSC functions in 2 modes – push (most basic) and pull. Creating a pull server is a non-trivial task and the out-of-the-box pull server has some issues. Some of the folks at powershell.org have decided its time to build a better pull server.

There’s a project on github that supplies the code for the open source, cross platform, pull server project known as tug.  pull – tug – pull… you get the picture.

You can find the project at https://github.com/PowerShellOrg/tug

If you’re using DSC download it, give it a try and feed back to the project what you’ve discovered. 

Diskpart and PowerShell – part 6: Multiple partitions on a disk

So far we’ve looked at creating a single partition on a disk. This time we’ll look at how you can create multiple partitions on a disk. The are good reasons not to do this but its something I’ve seen done on a frequent basis.

Lets create a 20GB disk as an example and mount it

New-VHD -Path C:\test\Test1.vhdx -Dynamic -SizeBytes 20GB 
Get-VHD -Path C:\test\Test1.vhdx | Mount-VHD

 

Initialise the disk

Initialize-Disk -Number 1

 

Now we can create some partitions

New-Partition -DiskNumber 1 -DriveLetter F -Size 5GB 
New-Partition -DiskNumber 1 -DriveLetter G -Size 5GB 
New-Partition -DiskNumber 1 -DriveLetter H -Size 5GB 
New-Partition -DiskNumber 1 -DriveLetter I -Size 4.87GB

 

The reason that the last partition is only 4.87 G is that 128MB of disk space is reserved

PS> Get-Partition -DiskNumber 1 | Format-Table -AutoSize


   DiskPath: \\?\scsi#disk&ven_msft&prod_virtual_disk#2&1f4adffe&0&000003#{53f56307-b6bf-11d0-94f2-00a0c91efb8b}

PartitionNumber DriveLetter Offset         Size Type 
--------------- ----------- ------         ---- ---- 
1                           17408        128 MB Reserved 
2               F           135266304      5 GB Basic 
3               G           5503975424     5 GB Basic 
4               H           10872684544    5 GB Basic 
5               I           16241393664 4.87 GB Basic

 

You can format the 4 new volumes in one pass

Get-Partition -DiskNumber 1 | 
where Type -ne 'Reserved' | 
Format-Volume -FileSystem NTFS -Confirm:$false –Force

 

PS> Get-Partition -DiskNumber 1 | Get-Volume | select DriveLetter, FileSystem, Size

DriveLetter FileSystem       Size 
----------- ----------       ---- 
          H NTFS       5368705024 
          G NTFS       5368705024 
          I NTFS       5229244416 
          F NTFS       5368705024

 

The Storage module can be used to simply and easily create multiple volumes on a disk

PowerShell in Azure Cloud Shell

if you are an Azure user see this post from the PowerShell team - https://blogs.msdn.microsoft.com/powershell/2017/05/23/coming-soon-powershell-in-azure-cloud-shell/

Diskpart and PowerShell – part4: Remove a partition

So far you’ve seen how to create and modify partitions and volumes. Its now time to look at how you remove a partition.

Mount the test VHD

Get-VHD -Path C:\test\Test1.vhdx | Mount-VHD

 

You can’t remove a volume – you have to remove the partition. Identifying the CORRECT partition to remove is the challenge

PS> Get-Partition | select PartitionNumber, DriveLetter, Size, Type

PartitionNumber DriveLetter         Size Type 
--------------- -----------         ---- ---- 
              1                134217728 Reserved 
              2           F   8589934592 Basic 
              1                367001600 IFS 
              2           C 511269232640 IFS 
              3                470810624 Unknown

 

Not every partition has a drive letter and partition numbers are repeated. The partition object holds the disk number

PS> Get-Partition | select DiskNumber, PartitionNumber, DriveLetter, Size, Type | Format-Table

DiskNumber PartitionNumber DriveLetter         Size Type 
---------- --------------- -----------         ---- ---- 
         1               1                134217728 Reserved 
         1               2           F   8589934592 Basic 
         0               1                367001600 IFS 
         0               2           C 511269232640 IFS 
         0               3                470810624 Unknown

 

So the combination of disk number and partition number is unique and will identify any partition. Remove our 8GB partition

Remove-Partition -DiskNumber 1 -PartitionNumber 2 -Confirm:$false

and the 128MB partition

Remove-Partition -DiskNumber 1 -PartitionNumber 1 -Confirm:$false

 

Get-Partition will show that the drive F: has been removed

Looking the disk organisation

Get-Disk -Number 1 | Select @{N='Size'; E={[math]::Round(($_.Size / 1GB), 2)}}, @{N='AllocatedSize'; E={[math]::Round(($_.AllocatedSize / 1GB), 2)}}, @{N='LargestFreeExtent'; E={[math]::Round(($_.LargestFreeExtent / 1GB), 2)}} | Format-List

Size              : 20 
AllocatedSize     : 0 
LargestFreeExtent : 20

 

The whole of the disk is now available for re-use

Diskpart and PowerShell–part 4: Expand a volume

Let’s create a new disk and mount it

New-VHD -Path C:\test\Test1.vhdx -Dynamic -SizeBytes 20GB 
Get-VHD -Path C:\test\Test1.vhdx | Mount-VHD 
Initialize-Disk -Number 1

 

This time we’ll create a volume that only uses part of the disk

New-Partition -DiskNumber 1 -DriveLetter F -Size 5GB

 

And now format the partition

Get-Partition -DriveLetter F | 
Format-Volume -FileSystem NTFS -Confirm:$false –Force

 

The disk is organised like this

Get-Disk -Number 1 | 
Select @{N='Size'; E={[math]::Round(($_.Size / 1GB), 2)}}, 
@{N='AllocatedSize'; E={[math]::Round(($_.AllocatedSize / 1GB), 2)}}, 
@{N='LargestFreeExtent'; E={[math]::Round(($_.LargestFreeExtent / 1GB), 2)}} | 
Format-List

 

Size              : 20 
AllocatedSize     : 5.13 
LargestFreeExtent : 14.87

 

Lets expand the partition

Get-Partition -DriveLetter F | 
Resize-Partition -Size 8GB

 

And re-examine the disk organisation

Get-Disk -Number 1 | 
Select @{N='Size'; E={[math]::Round(($_.Size / 1GB), 2)}}, 
@{N='AllocatedSize'; E={[math]::Round(($_.AllocatedSize / 1GB), 2)}}, 
@{N='LargestFreeExtent'; E={[math]::Round(($_.LargestFreeExtent / 1GB), 2)}} | 
Format-List

Size              : 20 
AllocatedSize     : 8.13 
LargestFreeExtent : 11.87

 

The extra space is added to the volume and formatted to match the existing filesystem on the volume