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Post OSD Scheduled Task

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Post OSD Scheduled Task


Every organization handles OSD differently. Currently at our organization we do have some apps that have been ‘baked into the task sequence’  as an ‘Install Application’ step for a very long time and are needed on every single imaged machine. These work perfectly, install consistently and generally there are no ‘exceptions’ to a PC having the software.

This isn’t the case with all of our widely distributed applications, and rather than build the logic into the task sequence we let the collections do the work after imaging. After a period of time when the appropriate collections are updated on their various schedules these new machines happily receive their software and baselines and go on their merry way as we know all healthy SCCM clients do! In the day-to-day SCCM world this works perfectly fine. Machines are added to collections through whatever method your organization uses, whether it be Direct Membership, AD Group/OU Queries, name based queries, hardware inventory based queries and there is a general understanding that machines will pop into the collection and receive their Applications/Updates/CIs in good time.

When our techs image a machine it can be helpful for it to temporarily have some expedited policy refresh rates for a period of time to speed up those after-the-fact deployments. We had tried a few collection queries to catch these ‘new machines’ so that we could deploy some aggressive Client Settings to them, but generally there is never a perfect query. Usually you catch not just new machines but instead those risen from the dead pit of being stale, or they were rejoined to the domain, maybe the client was reinstalled or some form of in place upgrade happened.  As an alternative to the collection query I wrote up a Powershell script.


What Does It Do?


It creates a scheduled task! 

The script can be ran from a ‘Run Command Line’ or ‘Run Powershell Script’ step during OSD (Typically near/at the end) with various parameter options. You’ll have to toss it into a package to serve up to the task sequence of course. It will create a scheduled task that runs specified SCCM Client Policy requests at whatever interval you want for as long as you want. Also, the task deletes itself shortly after the duration has passed. I didn’t quite include all the of schedule types because there is a very long list. But most of the key ones are there and any others can be easily added. 


How Do I Use It?


New-ClientActionScheduledTask.ps1 -Schedule MachinePol -Interval 5

This will create a schedule task that runs every 5 minutes for 24 hours. I did say aggressive at least once up there right? The task will receive a generated name based on the requested schedules. The above would produce a task named –
SCCM Action Scheduler – [MachinePol]
Which calls a file (Start-CMClientAction.ps1)  that is generated and stored in c:\windows\temp

Both the task name and the file name can be specified as parameters to the script aptly named… -FileName and -TaskName


New-ClientActionScheduledTask.ps1 -Schedule AppEval, HardwareInv, UpdateEval, UpdateScan -Interval 30 -Duration 12
Task Sequence Example

Similar results with this execution of the line above. A task is created, but with it running every 30 minutes for a 12 hour period. The task will appear in task scheduler with a title –
SCCM Action Scheduler – [AppEval,HardwareInv,UpdateEval,UpdateScan]
Which is based on the actions provided.


Where Do I Git It?


GitHub! I intend to continue adding to this GitHub repository.

https://github.com/CodyMathis123/CM-Ramblings/blob/master/New-ClientActionScheduledTask.ps1


Neat Stuff:


I’ve also used a couple of bits of code you might find interesting to create the scheduled task. Maybe you’ve seen it, maybe you haven’t.


${Function:Start-CMClientAction}

This will write-out the contents of many functions (note: function, not cmdlet). I am leveraging this to generate a .ps1 file that can be easily invoked by the task sequence.

Neat right? I wrote that function though… but what is more interesting is you can do this with some built in functions! Try ${function:Clear-Host} or ${function:Get-Verb} and you can see some of the magic behind at least some commands you’ve used. Many are compiled cmdlets and are simply not expandable like this but can be dug into in other ways.


$TaskDefinition.Settings.DeleteExpiredTaskAfter = "PT0S"

https://docs.microsoft.com/en-us/windows/desktop/taskschd/tasksettings-deleteexpiredtaskafter

While this can be a bit odd to work with, the above piece of code allows our scheduled task to ‘delete itself’ after it expires. Specifically… zero seconds after it expires. T is just a delimiter between date and time (Eg. days vs hours/minutes/seconds). You will need to specify an ‘EndBoundary’ for this to function, which is what our ‘Duration’ is in this.


function New-ScheduledTaskTimeString {
    param(
        [Parameter(Mandatory = $false)]
        [int]$Hours = 0,
        [Parameter(Mandatory = $false)]
        [int]$Minutes = 0
    )
    $TimeSpan = New-TimeSpan -Hours $Hours -Minutes $Minutes
    $TimeSpanDays = $TimeSpan | Select-Object -ExpandProperty Days
    $TimeSpanHours = $TimeSpan | Select-Object -ExpandProperty Hours
    $TimeSpanMinutes = $TimeSpan | Select-Object -ExpandProperty Minutes

    if ($TimeSpanDays -gt 0) {
        $OutputDays = [string]::Format("{0}D", $TimeSpanDays)
    }

    if ($TimeSpanHours -gt 0 -or $TimeSpanMinutes -gt 0) {
        $Delimiter = 'T'
        if ($TimeSpanHours -gt 0) {
            $OutputHours = [string]::Format("{0}H", $TimeSpanHours)
        }

        if ($TimeSpanMinutes -gt 0) {
            $OutputMinutes = [string]::Format("{0}M", $TimeSpanMinutes)
        }
    }

    [string]::Format("P{0}{1}{2}{3}", $OutputDays, $Delimiter, $OutputHours, $OutputMinutes)

}

You give me hours and minutes, I give you a PnDTnHnMnS string to use for a scheduled task.
Just a quick function I wrote for the purposes of dumping out usable strings for time intervals that task scheduler understands.


I opted to not use the *-ScheduledTask* commands available post-Win 7. You could ‘simplify’ the code a bit for the task creation if you don’t mind being incompatible with Windows 7 by using these.

Is this the right way to do it? Who knows! I’m sure with some very careful inspection and categorization of our collections and their refresh schedules we could help the situation in other ways. Still a neat bit of code.

Cody Mathis
@CodyMathis123