Get Computer's uptime

Get-Uptime.ps1

function Get-Uptime
{
    <#
        .SYNOPSIS
            Get Computer's uptime

        .DESCRIPTION
            Returns the total time since the last reboot

        .NOTES
            AUTHOR : Oliver Lipkau <oliver@lipkau.net>
            VERSION: 1.0.0 - OL - Initial Code

        .PARAMETER  ComputerName
            Hostname/IP of the remote computer

        .PARAMETER  Credential
            Authentication Credentials for the remote computer

        .INPUTS
            System.String
            System.Management.Automation.PSCredential

        .OUTPUTS
            System.TimeSpan
    #>
    [CmdletBinding()]
    [OutputType([TimeSpan] )]
    param(
        [string]$ComputerName = "localhost",

        [System.Management.Automation.PSCredential]$Credential
    )

    begin {  }

    process {
        if ($Credential)
        {
            $time = Get-WmiObject -class Win32_OperatingSystem -computer $ComputerName -Credential $Credential
        }
        else
        {
            $time = Get-WmiObject -class Win32_OperatingSystem -computer $ComputerName
        }
        $t = $time.ConvertToDateTime($time.Lastbootuptime)
        New-TimeSpan $t $(get-date)
    }

    end {  }
}

$upTime = Get-Uptime
"$($upTime.days)d $($upTime.hours)h $($upTime.minutes)m $($upTime.seconds)S"

Output for "$($upTime.days)d $($upTime.hours)h $($upTime.minutes)m $($upTime.seconds)S"

1d 23h 3m 20S