Advanced Windows PowerShell Scripting Video Training

Advanced Windows PowerShell Scripting Video Training
Advanced Windows PowerShell Scripting Video Training

Wednesday, January 4, 2017

Using functions with PowerShell Background Jobs Part 2 of 2

Yesterday we learned how to use the InitializationScript parameter of Start-Job. Today we are going to allow for further modularization of our code and send multiple functions to Start-Job.  We could very easily send multiple functions in the same script block, but I need to pick and choose which functions I will be working with for each process so I need to be able to send them separately.  Here is our code.




$JobFunction1 = {
 Function Beep
 {
    Param ($Tone)
    [console]::beep($Tone,200)
 }

}

$JobFunction2 = {
 Function Beep2
 {
    Param ($Tone, $Time)
    [console]::beep($Tone,$Time)
 }
}

$InitializationScript = $executioncontext.invokecommand.NewScriptBlock("$JobFunction1 $JobFunction2")

$JobSplat = @{
    Name = "Test1"
    InitializationScript = $InitializationScript
    ArgumentList = 300, 400, 200
}

Start-Job @JobSplat -ScriptBlock {
            Param($Value, $Tone, $Time)
            Beep -Tone $Value
            Beep2 -Tone $Tone -Time $Time
            }

A lot of the code is the same as yesterday with a few exceptions. Notice that we are creating $JobFunction1 and $JobFunction2.  This allows me to place a single function inside of a script block, but be able to send multiple script blocks to Start-Job.  I am also using the $ExecutionContext automatic variable. According to About_Automatic_Variables, this variable:
Contains an EngineIntrinsics object that represents the execution context of the Windows PowerShell host. You can use this variable to find the execution objects that are available to cmdlets.

OK, that was informative.  It is on object of type System.Management.Automation.EngineIntrinsics. In short, you can create new script blocks with it.  I use it to join the 2 variables containing the script blocks that I need to send to Start-Job. I save the output in a variable called $InitializationScript. This is now the value of –InitializationScript.


When you run this code, you will hear two beeps.

Tuesday, January 3, 2017

Using functions with PowerShell Background Jobs Part 1 of 2

Happy New Year everyone!  I am spending my New Years’ day working on some code that I’ve been putting off while the family has been in town.  Something about shoveling sunshine as opposed to shoveling snow.  I’m working on expanding some Azure code that I have developed and I’m looking at ways to further modularize the code.  Since I use Background jobs with script blocks to speed the processes that I am running, I’m looking at using the InitializationScript parameter of Start-Job.

The InitializationScript parameter allows you to run code before the ScriptBlock parameter runs.  When you include functions inside of it, you are able to place those functions in the same memory that the ScriptBlock will execute in.  Let’s take a look at our code to set this up.

First we create a variable that will hold our function that we will call from the background job.

$JobFunctions = {
 Function Beep
 {
    Param ($Tone)
    [console]::beep($Tone,200)
 }

}

In this case, we are going to make the console beep.  We are also going to pass the value for the tone of the beep to the parameter $Tone.

Next we will set up a splat for a few of the parameters of Start-Job. Notice that we are setting the value for –InitializationScript to be the $JobFunctions that we created above.  Also, we need to pass a value to what will be our script block.  That value is 300.

$JobSplat = @{
    Name = "Test1"
    InitializationScript = $JobFunctions
    ArgumentList = 300
}

Now we can run our background job.

Start-Job @JobSplat -ScriptBlock {
            Param($Value)
            Beep –Tone $Value
            }

First off we call our splat and then we call our script block.  We need to pass the value of 300 to the script block so we created a parameter called $Value. In other words $Value = 300.  Next we call the function that we sent to the initialization script.  The function name is Beep it has a parameter called –Tone.  We provide it the value of 300 that is contained in $Value.  Once this runs, you will hear a beep.


Tomorrow we will send multiple functions to our background job.