Run PowerBGInfo with Task Scheduler

Task Scheduler is the most direct way to refresh a wallpaper: it can start the script at sign-in, at unlock and on a timer, in the user's own session. The Group Policy, Intune and Configuration Manager guides deliver the same task.

When to use this route

• Standalone machines, labs, servers you sign in to, or any fleet where another tool can run the registration script once.
• Whenever the wallpaper should refresh while the user is signed in.

Prerequisites

• The module installed for all users and Set-BGInfoWallpaper.ps1 from Run in production in C:\Program Files\PowerBGInfo.
• An elevated session to register a task for all users. The task itself runs without elevation.
• Windows PowerShell 5.1 or PowerShell 7. The examples use powershell.exe; replace the path with C:\Program Files\PowerShell\7\pwsh.exe to use PowerShell 7.

Who the task runs as

A group principal is the scripted form of "Run only when user is logged on" for every user: Task Scheduler runs the task with the interactive token of the group member, so it can change that member's desktop. A SYSTEM task changes SYSTEM's own wallpaper, which nobody sees.

Two things are not documented by Microsoft and were not tested for this guide: which sessions a group task with a time trigger runs in when several members are signed in (a multi-session host, fast user switching), and whether -AllUsers run as SYSTEM finishes cleanly. With -AllUsers, the profile registry writes happen first; the following step applies the image to SYSTEM's own desktop and may fail in session 0. Test both on your build before relying on them.

Step 1: register the per-user task

Save this as Register-BGInfoTask.ps1 and run it once, elevated. It registers one task for all users with three triggers: sign-in (after 30 seconds, so Explorer is up), unlock, and every 30 minutes. -Force replaces an existing task, so it is safe to run again. The Intune and Configuration Manager installers in the other guides call this file.

# Register-BGInfoTask.ps1: run elevated, in 64-bit PowerShell.
$taskName = 'PowerBGInfo wallpaper'
$script = 'C:\Program Files\PowerBGInfo\Set-BGInfoWallpaper.ps1'
$shell = "$env:SystemRoot\System32\WindowsPowerShell\v1.0\powershell.exe"
$arguments = '-NoProfile -NonInteractive -WindowStyle Hidden ' +
    "-ExecutionPolicy Bypass -File `"$script`""
$action = New-ScheduledTaskAction -Execute $shell -Argument $arguments

$logon = New-ScheduledTaskTrigger -AtLogOn
$logon.Delay = 'PT30S'

$stateClass = Get-CimClass -ClassName MSFT_TaskSessionStateChangeTrigger `
    -Namespace 'Root/Microsoft/Windows/TaskScheduler'
$unlock = New-CimInstance -CimClass $stateClass -ClientOnly -Property @{
    StateChange = 8   # TASK_SESSION_UNLOCK
    Enabled     = $true
}

$timer = New-ScheduledTaskTrigger -Once -At (Get-Date).Date `
    -RepetitionInterval (New-TimeSpan -Minutes 30) `
    -RepetitionDuration (New-TimeSpan -Days 3650)

$principal = New-ScheduledTaskPrincipal -GroupId 'S-1-5-32-545' `
    -RunLevel Limited

$settings = New-ScheduledTaskSettingsSet -AllowStartIfOnBatteries `
    -DontStopIfGoingOnBatteries -StartWhenAvailable `
    -MultipleInstances Parallel `
    -ExecutionTimeLimit (New-TimeSpan -Minutes 5)

Register-ScheduledTask -TaskName $taskName -TaskPath '\PowerBGInfo\' `
    -Action $action -Trigger $logon, $unlock, $timer `
    -Principal $principal -Settings $settings -Force `
    -Description 'Renders the PowerBGInfo wallpaper for the signed-in user.'

What the pieces do:

• Parallel preserves a second user's trigger while another session is rendering. Each user writes to their own output directory; a group task using IgnoreNew would discard that second user's run. PowerBGInfo serializes generation for the same Windows user across processes and sessions, holding the lock through image rendering, origin tracking and application. Different users use separate locks. A run waits up to five minutes for an earlier run; an exited owner releases the lock.
• -AtLogOn without -User fires for any user who signs in.
• The unlock trigger is a SessionStateChangeTrigger with StateChange = 8 (TASK_SESSION_UNLOCK). New-ScheduledTaskTrigger has no parameter for it, so the trigger is created from its CIM class. Other values: 1 console connect, 3 remote connect (useful on Remote Desktop hosts), 7 lock.
• The trigger repeats every 30 minutes for ten years. Re-register it before the duration expires. Older ScheduledTasks modules require a finite -RepetitionDuration when -RepetitionInterval is supplied.
• New-ScheduledTaskSettingsSet defaults to not starting on battery and stopping when the laptop unplugs, and to a 72-hour execution time limit. The switches above change both.
• -ExecutionPolicy Bypass on the command line does not override an execution policy set by Group Policy. In an AllSigned environment, sign your scripts and trust the module's publisher (see Security and operations).
• -WindowStyle Hidden hides the console once PowerShell starts; a window can still flash briefly.

To use PowerShell 7, change $shell:

$shell = "$env:ProgramFiles\PowerShell\7\pwsh.exe"

Step 2 (optional): a machine-level task as SYSTEM

Use this for images that are not per-user: a lock screen image that a policy points at (see Group Policy and Microsoft Intune), or a staged default wallpaper. Save this as C:\Program Files\PowerBGInfo\Set-BGInfoMachineImage.ps1:

#Requires -Version 5.1
# Renders a machine-wide image as a file. Runs as SYSTEM: show machine
# facts only. UserName would be SYSTEM.
param(
    [string] $OutputDirectory = (
        Join-Path $env:ProgramData 'PowerBGInfo'),
    [string] $OutputFileName = 'LockScreen.jpg',
    [int] $Width = 1920,
    [int] $Height = 1080
)

$ErrorActionPreference = 'Stop'
Import-Module -Name PowerBGInfo
$facts = Get-BGInfoSystemInfo
$scale = [int]($Height / 10.8) / 100

New-BGInfo -Theme (New-BGInfoTheme -Preset Corporate -Scale $scale) `
    -Target File -ConfigurationDirectory $OutputDirectory `
    -OutputFileName $OutputFileName {
    New-BGInfoBackground -Width $Width -Height $Height
    New-BGInfoLabel -Name $facts.ComputerName -FontWeight 700
    New-BGInfoValue -Name 'Support' -Value 'ext. 4357'
}

A SYSTEM process has no monitor of its own, so the size is passed in. Choose the most common resolution and aspect ratio of the screens you deploy to; Windows resizes the lock screen image to each screen, so keep text away from the edges.

Register it, elevated:

$script = 'C:\Program Files\PowerBGInfo\Set-BGInfoMachineImage.ps1'
$shell = "$env:SystemRoot\System32\WindowsPowerShell\v1.0\powershell.exe"
$arguments = '-NoProfile -NonInteractive -ExecutionPolicy Bypass ' +
    "-File `"$script`""
$action = New-ScheduledTaskAction -Execute $shell -Argument $arguments
$triggers = @(
    New-ScheduledTaskTrigger -AtStartup
    New-ScheduledTaskTrigger -Daily -At '06:00'
)
$principal = New-ScheduledTaskPrincipal -UserId 'SYSTEM' `
    -LogonType ServiceAccount -RunLevel Highest
$settings = New-ScheduledTaskSettingsSet -AllowStartIfOnBatteries `
    -DontStopIfGoingOnBatteries -StartWhenAvailable `
    -ExecutionTimeLimit (New-TimeSpan -Minutes 5)

Register-ScheduledTask -TaskName 'PowerBGInfo machine image' `
    -TaskPath '\PowerBGInfo\' -Action $action -Trigger $triggers `
    -Principal $principal -Settings $settings -Force

Resolution and display changes

Task Scheduler has no trigger for a display or resolution change, and Microsoft does not document an event log entry for one that a custom event trigger could watch. There is no clean way to re-render the moment a laptop docks or a monitor is added. Practical options:

• The unlock trigger covers the common case of docking a locked laptop.
• The console connect (1) and remote connect (3) state changes cover switching users and reconnecting a remote session.
• The repeating trigger catches everything else within its interval.
• Rendering with New-BGInfoBackground at the monitor size and -WallpaperFit Fill keeps a stale image filling the screen until the next run, instead of leaving bars or tiles.

Verify

$task = Get-ScheduledTask -TaskPath '\PowerBGInfo\' `
    -TaskName 'PowerBGInfo wallpaper'
$task.Triggers | Select-Object CimClassName, Delay, StateChange
Start-ScheduledTask -InputObject $task
Start-Sleep -Seconds 20
Get-ScheduledTaskInfo -InputObject $task |
    Select-Object LastRunTime, LastTaskResult, NextRunTime

LastTaskResult is the script's exit code: 0 for success, 1 when the reference script caught an error. Then, as the user, read the transcript:

Get-Content (Join-Path $env:LOCALAPPDATA 'PowerBGInfo\last-run.log')

The task history in Task Scheduler (Event Viewer: Microsoft-Windows-TaskScheduler/Operational) records each start and the result. On many installations task history is turned off until you choose Enable All Tasks History in Task Scheduler.

Remove the tasks:

Get-ScheduledTask -TaskPath '\PowerBGInfo\' |
    Unregister-ScheduledTask -Confirm:$false

Pitfalls

• Running the per-user task as SYSTEM. It succeeds and changes nothing visible. Use the group principal.
• A shared output folder. Several users writing C:\ProgramData\PowerBGInfo\wallpaper-0.png overwrite each other, and a file created by one user usually cannot be replaced by another. The reference script writes to %LOCALAPPDATA%\PowerBGInfo.
• A 32-bit PowerShell. C:\Windows\SysWOW64\WindowsPowerShell does not see modules in C:\Program Files\WindowsPowerShell\Modules. Use the System32 path from a 64-bit registration.
• Too frequent a timer. Each run renders every monitor and reads WMI. 30 to 60 minutes is enough for most values; data that changes only at sign-in needs no timer at all.
• The task does nothing on battery. See the settings above.

Further reading

• New-ScheduledTaskTrigger
• New-ScheduledTaskPrincipal
• Register-ScheduledTask
• New-ScheduledTaskSettingsSet
• SessionStateChangeTrigger.StateChange
• Principal.LogonType
• RepetitionPattern.Duration
• about_Execution_Policies