Advanced Windows PowerShell Scripting Video Training

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

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. 

No comments: