Prof. Powershell

Command-Line Objects

Turn any command-line tool into a PowerShell tool.

• By Jeffery Hicks
• 06/14/2011

I'm sure you've heard me extol the wonders of PowerShell as an object-based shell. When you have objects in the pipeline you can sort, group, filter, export and much, much more.

I'm sure you also know you can still run legacy command-line tools in PowerShell. However, the challenge is that these commands don't lend themselves to the pipeline approach, since they don't write objects. But actually, they do: strings. But other than send output to a file, those strings won't do much for you. So, let me give you some techniques you can use to turn command-line tools into PowerShell tools.

For the sake of this lesson, I'm going to take the output of NBTSTAT /N and turn it into a PowerShell object:

PS C:\> nbtstat /n

Local Area Connection:
Node IpAddress: [10.23.36.71] Scope Id: []

        NetBIOS Local Name Table

   Name                 Type     Status
   ---------------------------------------
   QUARK          <20>  UNIQUE  Registered
   QUARK          <00>  UNIQUE  Registered
   JDHITSOLUTIONS <00>  GROUP   Registered

Wireless Network Connection:
Node IpAddress: [0.0.0.0] Scope Id: []

I'm going to focus on the registered name output and step through the process. You most likely want to turn this into a function you could reuse. So first, let's get the lines of interest:

PS C:\> $data=nbtstat /n | Select-String "<"
PS C:\> $data

   QUARK          <20>  UNIQUE   Registered
   QUARK          <00>  UNIQUE   Registered
   JDHITSOLUTIONS <00>  GROUP    Registered

I used Select-String to filter and saved the results to $data. Next, I'll split each line into an array. The tricky part is that because I used Select-String, each line is a MatchInfo object, not a string. I'll need to trim off spaces:

PS C:\> $lines=$data | foreach { $_.Line.Trim()}
PS C:\> $lines
QUARK          <20>  UNIQUE  Registered
QUARK          <00>  UNIQUE  Registered
JDHITSOLUTIONS <00>  GROUP   Registered

Now, I'll split each line on a space into an array using the -Split operator and a regular expression pattern. Then I'll then take each array element and create a new object:

PS C:\> $lines | foreach { $temp=$_ -split "\s+"
>> New-Object -TypeName PSObject -Property @{
>> Name=$temp[0]
>> NbtCode=$temp[1]
>> Type=$temp[2]
>> Status=$temp[3]
>> }
>> }
Name              NbtCode    Type      Status
----              -------    ----      ------
QUARK             <20>       UNIQUE    Registered
QUARK             <00>       UNIQUE    Registered
JDHITSOLUTIONS    <00>       GROUP     Registered

Again, I did this interactively and you'll want to encapsulate in a function. But the end result is a custom object with the properties I defined. You should be able to use these concepts and techniques for just about any command-line tool and turn it into a PowerShell tool.