To get the Windows System uptime with PowerShell, we can use the CIM Instance method with class name Win32_OperatingSystem. Once you use the mentioned class there is a property called LastBootupTime which shows the date when the computer is last rebooted.
Example
Get-CimInstance -ClassName Win32_OperatingSystem | Select LastBootUpTime
Output
Days : 6 Hours : 0 Minutes : 17 Seconds : 38 Milliseconds : 301 Ticks : 5194583016830 TotalDays : 6.01224886207176 TotalHours : 144.293972689722 TotalMinutes : 8657.63836138333 TotalSeconds : 519458.301683 TotalMilliseconds : 519458301.683
From the Output, we can say that the server is up from 6 Days and 17 minutes. We can also write the output as below.
Write-Output "Server Uptime --> Days: $($uptime.days), Hours: $($uptime.Hours), Minutes:$($uptime.Minutes)"
Output
Test1-Win2k12 Uptime : 5 Days, 22 Hours, 50 Minutes Test1-Win2k16 Uptime : 5 Days, 23 Hours, 12 Minutes ADDC Uptime : 6 Days, 2 Hours, 9 Minutes
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Output
Server Uptime --> Days: 6, Hours: 0, Minutes:17
To check the uptime on the remote computers, use –ComputerName parameter in the command. For example,
$servers = "Test1-Win2k12","Test1-Win2k16","ADDC"
$currentdate = Get-Date
foreach($server in $servers){
$Bootuptime = (Get-CimInstance -ClassName Win32_OperatingSystem -ComputerName $server).LastBootUpTime
$uptime = $currentdate - $Bootuptime
Write-Output "$server Uptime : $($uptime.Days) Days, $($uptime.Hours) Hours, $($uptime.Minutes) Minutes"
}Output
LastBootUpTime -------------- 9/29/2020 8:12:08 AM
If we check the datatype of the above output, it should be DateTime because of the output format.
(Get-CimInstance -ClassName Win32_OperatingSystem).LastBootUpTime.Gettype()
Output
IsPublic IsSerial Name BaseType -------- -------- ---- -------- True True DateTime System.ValueType
We need now the uptime of the system in Days–Hours–Minutes format. So we will compare the difference between the current date/time with the Bootup date/time.
$bootuptime = (Get-CimInstance -ClassName Win32_OperatingSystem).LastBootUpTime $CurrentDate = Get-Date $uptime = $CurrentDate - $bootuptime $uptime
