MD5 Hash function

Had to get the MD5 Hash on some files and needed a light weight script. So here it is:

function Get-Md5Hash
{
    <#
        .SYNOPSIS
        This function returns the Md5 Hash for a given file.
 
        .DESCRIPTION
        This function returns the Md5 Hash for a given file.
        You can Pipe in files or just use one at a time.
 

        .EXAMPLE
        PS C:\> $ReturnedHash = Get-Md5Hash "c:\test\MyFile.txt"
 
        .EXAMPLE
        PS C:\> @("C:\TEST\TestFile1.txt","C:\TEST\TestFile2.txt","C:\TEST\TestFile3.txt") | Get-Md5Hash
 
        .INPUTS
        A file name/location.
 
        .OUTPUTS
        The Md5 Hash of the given file is returned.
 
        .NOTES
        Function Name: Get-Md5Hash
        Original Author: Norman Skinner (normans)
        Original Created on: 09/26/2013
        Version: 1.0.0.0
 
        HISTORY:
        ===========#==============#======================================
        Date       | User         | Description
        -----------+--------------+--------------------------------------
        09/26/2013 | normans      | Created script
        -----------+--------------+--------------------------------------
                   |              | 
        -----------+--------------+--------------------------------------
                   |              | 
        -----------+--------------+--------------------------------------
    #>
 
    param
    (
        [parameter(Mandatory=$true,ValueFromPipeline=$true)]
        [string]
        # This the file for getting the Md5 hash.
        $File
    )
    PROCESS
    {
        $MD5object = new-object -TypeName System.Security.Cryptography.MD5CryptoServiceProvider
        $Md5Hash   = [System.BitConverter]::ToString($MD5object.ComputeHash([System.IO.File]::ReadAllBytes($File)))
        return $Md5Hash
    }
}

Merge hash tables like shuffling cards.

Continuing on my work with hash tables, I have created a the new function “Merge-Hashtables”. For my own convenience I added two switches. One to remove NULLs and another to force the use of the second hash tables values when two keys match.

I have added a few examples to the function help on the use and output examples.

function Merge-Hashtables
{
    <#
    .SYNOPSIS
    Merges two hash tables with the option to remove all null key/value pairs.
     
    .DESCRIPTION
    This function will take two hash tables and merge the second hash table
    to the first. Any keys in the second hash table that exist in the 
     
    .EXAMPLE

    Merge-Hashtables $HashOne $HashTwo
    
    The basic example will merge the two hashtables not removing nulls
    and skipping existing keys from the second hashtable.
    
    Deeper Example:
    ===========================================================================
    PS C:\> $HashOne = @{One='1';Two='2';Three=$null}
    PS C:\> $HashTwo = @{Two='Two';Three='3';Four='4';Five='5'}
    PS C:\> Merge-Hashtables $HashOne $HashTwo

    Name                           Value
    ----                           -----
    Five                           5
    Two                            2
    Three
    One                            1
    Four                           4
    
    .EXAMPLE
    
    Merge-Hashtables $HashOne $HashTwo -RemoveNulValues
    
    This example removes key value pairs that have a value of NULL.
    Also it skips merging existing keys from the second hashtable.
    
    Deeper Example:
    ===========================================================================
    C:\PS> $HashOne = @{One='1';Two='2';Three=$null}
    C:\PS> $HashTwo = @{Two='Two';Three='3';Four='4';Five='5'}
    C:\PS> Merge-Hashtables $HashOne $HashTwo -RemoveNulValues

    Name                           Value
    ----                           -----
    Five                           5
    Two                            2
    One                            1
    Four                           4

    .EXAMPLE
    
    Merge-Hashtables $HashOne $HashTwo -RemoveNulValues -ForceValue
    
    This example removes key value pairs that have a value of NULL.
    Also on existing keys it updates the value with the value from
    the second hashtable.
    
    This example 
    
    Deeper Example:
    ===========================================================================
    PS C:\> $HashOne = @{One='1';Two='2';Three=$null}
    PS C:\> $HashTwo = @{Two='Two';Three='3';Four='4';Five='5'}
    PS C:\> Merge-Hashtables $HashOne $HashTwo -RemoveNulValues -ForceValue

    Name                           Value
    ----                           -----
    Five                           5
    Two                            Two
    Three                          3
    One                            1
    Four                           4

    .NOTES
    Original Author: Norman Skinner (Edgile Inc.) (v-nskin)
    Original Created on: 11/30/2012
    Version: 1.0.0.0
     
    HISTORY:
    ===========#==============#======================================
    Date       | User         | Description
    -----------+--------------+--------------------------------------
    11/30/2012 | v-nskin      | Created script
    -----------+--------------+--------------------------------------
               |              | 
    -----------+--------------+--------------------------------------
               |              | 
    -----------+--------------+--------------------------------------
               |              | 
    -----------+--------------+--------------------------------------
    #>
    [CmdletBinding()]
    param
    (
        [parameter(Mandatory=$true,position=0,HelpMessage= 'Enter the first hashtable to be merged into.')]
        [hashtable]
        # The hashtable to be merged into.
        $HashTable,
        [parameter(Mandatory=$true,position=1,HelpMessage= 'Enter the second hashtable to be merged into the first hashtable.')]
        [hashtable]
        # The second hash table to be merged into the first hash table.
        $HashTableToMerger,
        [switch]
        <#
            If this switch is used, any keys that exist in the first hash table will have their values updated
            with matching keys value in the second hash table.
        #>
        $ForceValue = $false,
        [switch]
        # If this switch is used, all key/value pairs with NULL values will be removed.
        $RemoveNulValues = $false
        
    )

    Set-StrictMode -Version 'Latest'
    $VerbosePreference     = 'Continue'
    $ProgressPreference    = 'SilentlyContinue'
    $ErrorActionPreference = 'Stop'

    foreach($Key in [array]$HashTableToMerger.Keys)
    {
        if ($HashTable.ContainsKey($Key))
        {
            if ($ForceValue)
            {
                # Force the value update for this key
                $HashTable[$Key] = $HashTableToMerger[$Key]
            }
        }
        else
        {
            # Add the new key value pair
            $HashTable.Add($Key, $HashTableToMerger[$Key])
        }
    }
    
    if ($RemoveNulValues)
    {
        foreach($Key in [array]$HashTable.Keys)
        {
            if ($HashTable[$Key] -eq $null)
            {
                $HashTable.Remove($Key)
            }
        }
    }

    Write-Output $HashTable
}

Remove item from a hashtable.

I had an issue removing nulls values from hashtables Key/Value pair. So I wrote a function to make quick work of it.

By converting the hasktables key collection to an array, I do not get an error removing key/value pairs while iterating over the hash.

function Remove-HashtableNulls
{
    <#
    .SYNOPSIS
    Removes any Key pairs that have a NULL value.
     
    .DESCRIPTION
    This function will take a hashtable and iterate over all the
    Key pairs and remove any that have a NULL for the value. It 
    will then return the edited hashtable.
     
    .EXAMPLE
    PS C:\> $TestHash = Remove-HashtableNulls $TestHash
 
    .EXAMPLE
    PS C:\> $TestHash = Remove-HashtableNulls -HashTable $TestHash
 
    .NOTES
    Original Author: Norman Skinner (Edgile Inc.) (Norman.Skinner@Edgile.com)
    Original Created on: 11/30/2012
    Version: 1.0.0.0
     
    HISTORY:
    ===========#================#======================================
    Date       | User           | Description
    -----------+----------------+--------------------------------------
    11/30/2012 | Norman Skinner | Created script
    -----------+----------------+--------------------------------------
               |                | 
    -----------+----------------+--------------------------------------
    #>
    [CmdletBinding()]
    param
    (
        [parameter(Mandatory=$true, HelpMessage= 'Enter a hashtable for null removals.')]
        [hashtable]
        # The hashtable that will have any null valuses removed.
        $HashTable
    )
 
    Set-StrictMode -Version 'Latest'
    $VerbosePreference     = 'Continue'
    $ProgressPreference    = 'SilentlyContinue'
    $ErrorActionPreference = 'Stop'
 
    foreach($Key in [array]$HashTable.Keys)
    {
        if ($HashTable[$Key] -eq $null)
        {
            $HashTable.Remove($Key)
        }
    }
    
    Write-Output $HashTable
}

Check if Running As Administrator

Have you ever had a script that requires it be run in “Run As Administrator” mode and needed a function to check that? When I run into this I use the following function:

function Confirm-RunningAsAdministrator
{
<# 
.SYNOPSIS 
This function will return a bool, "True" if running as administrator,
"False" if not.
  
.DESCRIPTION 
You can use this script to check is you are currently running as
administrator. It is best used when your script needs to verify
that this is the case.
  
.EXAMPLE 
    if (Confirm-RunningAsAdministrator)
    {
        Write-Host "Running as an administrator."
    }
    else
    {
        Write-Host "NOT running as an administrator."
    }

    ----------------------------------------------------------- 
    If running as an administrator, this would produce: 
      
Running as an administrator. 
  
.INPUTS 
None. 
  
.OUTPUTS 
[bool] - "True" if running as administrator, "False" if not. 
  
.NOTES 
Original Function name: Confirm-RunningAsAdministrator.ps1 
Original Author: Norman Skinner 
Original Created on: 12/05/2012 

HISTORY:
    ===========#================#=========#============================
    Date       | User           | Version | Description
    -----------+----------------+---------+----------------------------
    12/05/2011 | Norman Skinner | 1.0.0.0 | Created script
    -----------+----------------+---------+----------------------------
               |                |         |
    -----------+----------------+---------+----------------------------
#> 
    $WinIdentity = [Security.Principal.WindowsIdentity]::GetCurrent()
    $currentPrincipal = New-Object Security.Principal.WindowsPrincipal($WinIdentity)
    $AdministratorRole =  [Security.Principal.WindowsBuiltInRole]::Administrator 
    return $currentPrincipal.IsInRole($AdministratorRole)
}

Write-NoteStart

Once in a while I have to output information from a script that will say what I am doing and then if it completed or failed. In most cases it would look horrible on the screen. Like so:

Checking network connection...completed.
Checking file...completed.
Writing network information to file...completed.

This bugged me to no end; so I wrote the “Write-NoteStart” function to make it easier for me to sleep at night. When using this function the output looks more like this:

Checking network connection.............completed.
Checking file...........................completed.
Writing network information to file.....completed.

Here is the function:

function Write-NoteStart
{
<#
.SYNOPSIS
This function will place periods after writing a string and not write a new line.

.DESCRIPTION
This script is used to produce dots/periods after a given string for aligning
results. You can adjust the position it should add dots up to.

.EXAMPLE
    Write-NoteStart "Checking status" -DotTo 40
    Write-Host "completed."
    Write-NoteStart "Checking your connection" -DotTo 40
    Write-Host "completed."
    -----------------------------------------------------------
    This would produce:
    
Checking status.........................completed.
Checking your connection................completed.

.INPUTS
A string and an int.


.OUTPUTS
Write-Host to the screen with your string followed by periods.

.NOTES
Original Function name: Write-NoteStart.ps1
Original Author: Norman Skinner
Original Created on: 02/01/2012
Version: 1.0.0.0

#>
    param (
        [string]
        # The string for the start of the line.
        $Note = "No data",
        [int]
        # What line position to run dots to.
        $DotTo = 60
    )
    if ($Note.Length -lt $DotTo)
    {
        Write-Host $Note -NoNewline
        for ($i = $Note.Length;$i -lt $DotTo; $i++)
        {
            Write-Host "." -NoNewline
        }
    }
    else
    {
        Write-Host $Note
    }
}