Solving Problems with PowerShell (Part 1)

by Apr 3, 2023

PowerShell offers you a plentitude of approaches to solve a task. They always boil down to the same strategies. In this mini-series, we will illustrate them all one by one.

Here’s the problem to solve: get the MAC address of your computer.

The easiest way to tackle the problem is to find a command that can do this for you. Researching commands via Get-Command is the first step:

PS C:\> Get-Command -Name *get*mac*

CommandType     Name                                               Version    Source
-----------     ----                                               -------    ------
Function        Get-DbaSchemaChangeHistory                         1.1.143    dbatools
Function        Get-NetworkControllerMacPool                 NetworkController
Function        Get-VIMachineCertificate                           12.4.1.... VMware.PowerCLI.VCenter
Function        Invoke-GetVmClassNamespaceManagementVirtualMach... 1.0.104... VMware.Sdk.vSphere.vCenter.NamespaceManagement
Cmdlet          Get-AlarmAction                                    12.4.0.... VMware.VimAutomation.Core
Cmdlet          Get-AlarmActionTrigger                             12.4.0.... VMware.VimAutomation.Core
Cmdlet          Get-PnPCustomAction                                1.12.27    PnP.PowerShell
Cmdlet          Get-PnPCustomAction                                3.29.21... SharePointPnPPowerShellOnline
Application     getmac.exe                                         10.0.19... C:\WINDOWS\system32\getmac.exe

Getmac.exe sounds promising, and it can easily solve the puzzle:

PS C:\> getmac

Physical Address    Transport Name
=================== ==========================================================
24-EE-9A-54-1B-E5   Media disconnected
24-EE-9A-54-1B-E9   Media disconnected
80-3F-5D-05-58-91   \Device\Tcpip_{44FE83FC-7565-4B18-AAC8-AB3EC075E822}
00-15-5D-58-46-A8   \Device\Tcpip_{DC7C0CE2-B070-4070-B5CB-1C400DA69AF8}

Unfortunately, getmac is of command type “Application” so it is an executable. This means to you:

  • It may not be available on another platform
  • Results are plain text and not structured

If *reading* the MAC address off screen is sufficient and if you deal with Windows only, you may be happy. Else, the next step would be searching for a better command by extending your search criteria and/or googling.

Soon it will turn out there’s also a PowerShell cmdlet called Get-NetAdapter that does the trick:

PS C:\> Get-NetAdapter

Name                      InterfaceDescription                    ifIndex Status       MacAddress             LinkSpeed
----                      --------------------                    ------- ------       ----------             ---------
vEthernet (Default Swi... Hyper-V Virtual Ethernet Adapter             28 Up           00-15-5D-58-46-A8        10 Gbps
WLAN                      Killer(R) Wi-Fi 6 AX1650s 160MHz Wir...      15 Disconnected 24-EE-9A-54-1B-E5       780 Mbps
Ethernet 2                USB Ethernet                                 11 Up           80-3F-5D-05-58-91         1 Gbps
Bluetooth-Netzwerkverb... Bluetooth Device (Personal Area Netw...       9 Disconnected 24-EE-9A-54-1B-E9         3 Mbps

PS C:\> Get-Command -Name Get-NetAdapter | ft -AutoSize

CommandType Name           Version Source
----------- ----           ------- ------ 
Function    Get-NetAdapter NetAdapter 

Get-Command reveals: it is a “function”. Both “function” and “cmdlet” resemble PowerShell commands (commonly simplified as cmdlets). That’s good because it means to you:

  • The command most likely works cross-platform
  • The results are object-oriented (structured)

Since cmdlets return structured data, it’s easy for you to access particular data like the MacAddress by specifying its “column” (or property):

PS C:\> (Get-NetAdapter).MacAddress

All PowerShell cmdlets ship in modules, so if you found a useful cmdlet, make sure you also take a look at the related cmdlets in the same module:

PS C:\> Get-Command -Module (Get-Command -Name Get-NetAdapter).Source

CommandType     Name                                               Version    Source
-----------     ----                                               -------    ------
Function        Disable-NetAdapter                           NetAdapter
Function        Disable-NetAdapterBinding                    NetAdapter
Function        Disable-NetAdapterChecksumOffload            NetAdapter
Function        Disable-NetAdapterEncapsulatedPacketTaskOffload    NetAdapter
Function        Disable-NetAdapterIPsecOffload               NetAdapter

The takeaway for today:

  • Take your time to search for commands. Finding a command close to what you want is so much easier than using generic commands and reinvent the wheel
  • Try to use PowerShell cmdlets. Applications work, too, but only as a last resort

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