converting datetime from wmiobject to datetime

Question

Trying to get the difference in days between to dates: Today's date. and a date/time from a wmiobject (this was taken from a post from the PendingReboot script from Hey, Scripting! blog):

$Lastreboottime = Get-WmiObject win32_operatingsystem -ComputerName $Computer | 
select csname, @{LABEL='LastBootUpTime';EXPRESSION=$_.ConverttoDateTime($_.lastbootuptime)}} 
$Today = Get-Date -Format d
$DiffDays = $Today - $Lastreboottime

The result of $Today is

09/06/2016

and $Lastreboottime is

05/05/2016 11:13:21

So I want to get rid of the time but not sure how to do this.

Secondly, I get this error if I were to run the script, though I guess this may go away if I am able to extract the date only in $Lastreboot

Cannot convert the "@{csname=JDWTAWEB1; LastBootUpTime=05/05/2016 11:13:21}" value of type "Selected.System.Management.ManagementObject" to type "System.DateTime".

Any ideas?

score 2 · Accepted Answer · answered Jun 09 '16 at 17:24

2

Remove -Format d and compare the Date-properties of the DateTime-objects to get the days-diff only.
Your $Lastreboottime-variable references an object with both computername csname and the LastBootUpTime, so you need to access the LastBootUpTime

Try:

$Lastreboottime = Get-WmiObject win32_operatingsystem | 
select csname, @{LABEL='LastBootUpTime';EXPRESSION={$_.ConverttoDateTime($_.lastbootuptime)}}

$Today = Get-Date
$DiffDays = $Today.Date - $Lastreboottime.LastBootUpTime.Date

$DiffDays.TotalDays
13

answered Jun 09 '16 at 17:24

Frode F.

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How can we achieve this in below CSV format? Get-WmiObject win32_operatingsystem | ConvertTo-Csv | ConvertFrom-Csv | select csname, @{LABEL='LastBootUpTime';EXPRESSION={$_.ConverttoDateTime($_.lastbootuptime)}} – manjesh23 Jan 21 '22 at 08:34

score 1 · Answer 2 · answered Jun 09 '16 at 17:04

I think that the WMIObject conversion might need to get to a Datetime object by way of a properly formatted string. I did this (minus the -Computername $Computer part) and it seemed to work.

[string]$BootTimeString=(Get-WmiObject win32_operatingsystem -ComputerName $Computer).lastbootuptime -replace '\..*',''

$BootTimeDT=[datetime]::ParseExact($BootTimeString,'yyyyMMddHHmmss',$null)

$DiffDays = (NEW-TIMESPAN –Start $BootTimeDT –End (Get-Date)).Days

score 0 · Answer 3 · answered Jun 09 '16 at 16:57

Remove -Format d from Get-Date. You need DateTime object, not a string.
$Lastreboottime is an object with 2 properties: csname and lastbootuptime. You have to use lastbootuptime property.

Example:

$Today = Get-Date
$DiffDays = $Today - $Lastreboottime.lastbootuptime

converting datetime from wmiobject to datetime

3 Answers3

Example: