SharePoint 2013 : enable the Developer Dashboard from PowerShell

To enable the Developer Dashboard from PowerShell, you can use the following lines of script; just
make sure to turn it off when you finish using it in production:

$contentService = ([Microsoft.SharePoint.Administration.SPWebService]::
ContentService)
$devDashboardSettings =$contentService .DeveloperDashboardSettings
$devDashboardSettings.DisplayLevel =
[Microsoft.SharePoint.Administration.SPDeveloperDashboardLevel]::On
$devDashboardSettings.Update()


Note: the Developer Dashboard is a farm-wide setting