Start a detached background process in PowerShell

Question

I have a Java program which I would like to launch as a background process from a PowerShell script, similar to the way a daemon runs on Linux. The PowerShell script needs

Answer 1

Use jobs for this:

Start-Job -ScriptBlock {
  & java -jar MyProgram.jar >console.out 2>console.err
}

Another option would be Start-Process:

Start-Process java -ArgumentList '-jar', 'MyProgram.jar' `
  -RedirectStandardOutput '.\console.out' -RedirectStandardError '.\console.err'

Answer 2

Consider using the task scheduler for this. Define a task and set it without any triggers. That will allow you to simply "Run" (manually trigger) the task.

You can set up and/or trigger scheduled tasks using the ScheduledTasks powershell module, or you can use the GUI.

Answer 3

Old question, but since I had the same goal, I used answer from @use to acheive it.

So here is my code :)

$NAME_TASK = "myTask"
$NAME_TASKPATH = "\myPath\"

if ($args[0] -eq "-task") {
  # Code to be run "detached" here...
  Unregister-ScheduledTask -TaskName $NAME_TASK -TaskPath $NAME_TASKPATH -Confirm:$False
  Exit
}

$Task = (Get-ScheduledTask -TaskName $NAME_TASK -TaskPath $NAME_TASKPATH -ErrorAction 'SilentlyContinue')
if ($Task) {
  Write-Host "ERR: Task already in progress"
  Exit 1
}

$A = New-ScheduledTaskAction -Execute "PowerShell.exe" -Argument "-ExecutionPolicy bypass -NoProfile -Command ""$PSCommandPath -task $args"""
Register-ScheduledTask -TaskName $NAME_TASK -TaskPath $NAME_TASKPATH -Action $A | Start-ScheduledTask

Answer 4

This is an old post but since I have it working fine thought it might help to share. Its the call to 'java' instead of 'javaw' that is likely your issue. Ran it out myself using my JEdit java program through powershell to launch it.

#Requires -Version 3.0
$MyDriveRoot = (Get-Location).Drive.Root
$JEditDir = $($mydriveroot + "jEdit") ;# Should be C:\jEdit or wherever you want. JEdit is a sub-directory.
$jEdit = $($JEditDir + "\jedit.jar" )
$jEditSettings = $($JEditDir + "\settings")
$JEditLogs = $($JEditDir + "\logs")

Start-Process -FilePath javaw -ArgumentList ( '-jar',"$jEdit", '-settings="$JEditSettings"' ) -RedirectStandardOutput "$JEditLogs\console.out" -RedirectStandardError "$JEditLogs\console.err"

Which you can turn into a little function and then an alias to make it easy to launch in Powershell.

If ( ( Test-Path $jedit) ) {
    Function Start-JEdit() {
        Start-Process -FilePath javaw -ArgumentList ( '-jar',"$jEdit", '-settings="$($mydriveroot + "jEdit\settings")"' ) -RedirectStandardOutput "$JEditLogs\console.out" -RedirectStandardError "$JEditLogs\console.err"
    }
New-Alias -Name jedit  -Force Start-JEdit  -Description "Start JEdit programmers text editor" 
}