January 2016 Script Puzzle

Get-Uptime.ps1

<#
.SYNOPSIS
Gets the uptime of one or more computers.

.PARAMETER Name
The name of the computer(s) that you want to run this command against.  By default it will run against the local machine.  You can pass multiple computers separated with comma, or pass objects to it via the pipe.

.EXAMPLE
Get-Uptime

With no parameters passed, this will get the uptime of the local machine

ComputerName     : TS-SA-12345
StartTime        : 2/10/2016 7:35:21 AM
Uptime (Days)    : 0.3
Status           : OK
MightNeedPatched : False

.EXAMPLE
Get-Uptime -Name SERVER1

Check the uptime of a single computer named SERVER1

ComputerName     : SERVER1
StartTime        : 1/31/2016 12:00:00 AM
Uptime (Days)    : 10.3
Status           : OK
MightNeedPatched : False

.EXAMPLE
Get-Uptime -Name SERVER1,SERVER2,SERVER3 | Format-Table -Autosize

This example passes three computer names to Get-Uptime named SERVER1, SERVER2 and SERVER3

ComputerName StartTime            Uptime (Days) Status  MightNeedPatched
------------ ---------            ------------- ------  ----------------
SERVER1      1/31/2016 5:54:26 AM 10.3          OK                 False
SERVER2      1/31/2016 5:45:40 AM 10.3          OK                 False
SERVER3                                         OFFLINE            False

.EXAMPLE
Get-ADComputer SERVER1 | Get-Uptime

In this example, we use Get-ADComputer (from the ActiveDirectory module) to get the SERVER1 computer object.  Then we pass that object to Get-Uptime.

ComputerName     : SERVER1
StartTime        : 1/31/2016 12:00:00 AM
Uptime (Days)    : 10.3
Status           : OK
MightNeedPatched : False

.INPUTS

String. You can pass computer name via the $Name parameter to Get-Uptime

.OUTPUTS

System.Management.Automation.PSCustomObject

#>
function Get-Uptime{
    # This sets the function up to accept objects as input
    [CmdletBinding()]
    param (
        [Parameter(ValueFromPipeline=$true,ValueFromPipelinebyPropertyName=$true)]
        [string[]]$Name=$env:computername)

    PROCESS {
        foreach ($comp in $Name)
        {
            try {
                # Pre-build our object
                $outputObject = [Ordered]@{
                    'ComputerName' = $comp
                    'StartTime' = $null
                    'Uptime (Days)' = $null
                    'Status' = $null
                    'MightNeedPatched' = $false
                }
                
                
                #Test to see if the computer is alive
                Write-Verbose -Message "[$comp]: Attempting to connect with computer."
                if (-not(Test-Connection -ComputerName $comp -Count 1 -Quiet)) {
                    # Set the status to offline and throw an exception
                    $outputObject.Status = "OFFLINE"
                    throw "The computer [$($comp)] is offline."
                }
                # Set the status to OK
                $outputObject.Status = "OK"

                # Get the time object and calculate length of time since last boot
                Write-Verbose -Message "[$comp]: Calculating uptime days."
                $obj = Get-WmiObject -Class Win32_OperatingSystem -ComputerName $comp
                $time = $obj.ConvertToDateTime($obj.LocalDateTime) - $obj.ConvertToDateTime($obj.LastBootUpTime)
                
                # Set the Start Time                
                $outputObject.StartTime = $obj.ConvertToDateTime($obj.LastBootUpTime)
                                
                # Set the Uptime (Days) parameter and format it to only extend one decimal point
                $outputObject.'Uptime (Days)' = "{0:N1}" -f $time.TotalDays

                # Make patching determination based on total days since last boot
                Write-Verbose -Message "[$comp]: Checking if computer may need patching."
                if ($time.TotalDays -gt '30') {
                    $outputObject.MightNeedPatched = $true
                } else { $outputObject.MightNeedPatched = $false }
            }
            catch
            {
                # This assumes a problem with communicating to the computer object
                Write-Verbose -Message $_.Exception.Message
            }
            finally
            {
                # output the object regardless of thrown error.
                [pscustomobject]$outputObject
            } # try
        }# foreach
    }# process
}# function

3 quick tips:
1: if you name your Gist with a .ps1 extension, it will automatically add syntax highlighting
2: Unless you have a really good reason to, you should never clear the error counter (there are exceptions, certain cmdlets don't throw errors in a way try/catch can use, so you have to get creative). You should capture the error in your catch block and handle it there. Also, setting your error action to "SilentlyContinue" effectively makes your try/catch block useless.
3: You don't need to build a PSSession for this; Get-CimInstance and Get-WmiObject both have a -ComputerName argument that will work just fine and handle the session automatically (no set up or tear down needed)

Thank you for the tips! I'll see if I can incorporate them all and maybe make the code a little cleaner, I appreciate it!