Creating a DateTime object with a specific UTC DateTime in PowerShell

Question

I'm trying to create a DateTime object with a specific UTC timestamp in PowerShell. What's the simplest way to do this?

I tried:

Get-Date
    -Format (Get-Culture).DateTimeFormat.UniversalSortableDateTimePattern
    -Date "1970-01-01 00:00:00Z"

but I get this output:

1969-12-31 19:00:00Z

It's a few hours off. Where's my lapse in understanding?

Answer 1

The DateTime object itself is being created with the proper UTC time. But when PowerShell prints it out it converts it to my local culture and time zone, thus the difference.

Proof:

$UtcTime = Get-Date -Date "1970-01-01 00:00:00Z"
$UtcTime.ToUniversalTime()

Answer 2

(get-date).ToUniversalTime().ToString("yyyyMMddTHHmmssfffffffZ")

Answer 3

$utctime = New-Object DateTime 1970, 1, 1, 0, 0, 0, ([DateTimeKind]::Utc)

If you print out $utctime, then you get:

1. januar 1970 00:00:00

Also, $utctime.Kind is correctly set to Utc.

Answer 4

$time = [DateTime]::UtcNow | get-date -Format "yyyy-MM-ddTHH:mm:ssZ"

This appears to also work

Answer 5

You can use the SpecifyKind method:

PS C:\IT\s3> $timestamp

Wednesday, July 18, 2018 7:57:14 PM

PS C:\IT\s3> $timestamp.kind

Unspecified

PS C:\IT\s3> $utctimestamp = [DateTime]::SpecifyKind($timestamp,[DateTimeKind]::Utc)

PS C:\IT\s3> $utctimestamp

Wednesday, July 18, 2018 7:57:14 PM

PS C:\IT\s3> $utctimestamp.kind

Utc

Answer 6

This is how it works in .NET, right? PowerShell just calls the ToUniversalTime method. From http://msdn.microsoft.com/en-us/library/system.datetime.touniversaltime.aspx

The Coordinated Universal Time (UTC) is equal to the local time minus the 
UTC offset. For more information about the UTC offset, see TimeZone.GetUtcOffset.
The conversion also takes into account the daylight saving time rule that applies 
to the time represented by the current DateTime object.