UNIX time in Powershell giving GMT

Question

First off, I'm not a coder by profession, just a lowly network engineer :) But I'm a big believer in automation and try to write scripts to handle tasks they're suited for

I'm attempting to get the current UNIX timestamp for 10 minutes ago in PowerShell, for use in a database-check script. I'm using this to get the current Unix-time:

$unixtime=[int][double]::Parse((Get-Date -UFormat %s))-600

But when I run it through a UNIX-time to local time converter (http://www.onlineconversion.com/unix_time.htm), I'm getting the current time in GMT (for example, if I run it right now I get "1340620608", which the converter says is 10:36 AM GMT, when the actual time is 10:36 AM CDT). This obviously causes issues when comparing to Unix timestamps in the database, as they are in local time. While I could write (or find) a function that would calculate the current GMT offset and apply it to my timestamp, I was wondering if there is a better way to go about this.

russellds · Accepted Answer · 2012-06-25 16:38:30Z

4

Try:

$unixtime=[int][double]::Parse($(Get-Date -date (Get-Date).ToUniversalTime()-uformat %s))

The above gets the current GMT time first then converts it to the correct format.

answered Jun 25, 2012 at 16:38

russellds

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2 Comments

Greg Dickinson Over a year ago

Perfection! :) Thanks for this, it makes more sense now that I realized that the issue was the "pre-conversion" time was in local time.

phuclv Over a year ago

You just need [long]($(Get-Date -date (Get-Date).ToUniversalTime()-uformat %s)). No need to parse like that. Besides you'll need [long] to avoid y2k38 issue anyway. Never use int

Shay Levy · Accepted Answer · 2012-06-25 18:36:09Z

2

Does this work for you?

(Get-Date).AddMinutes(-10).Subtract((Get-Date 1/1/1970)).TotalSeconds

answered Jun 25, 2012 at 18:36

Shay Levy

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Comments

Keith Thompson · Accepted Answer · 2012-06-25 16:38:49Z

1

Unix timestamps are defined as seconds since 1970-01-01 00:00:00 GMT.

If the timestamps in your database are stored as seconds since 1970 local time, perhaps you need to fix your database. But it's likely that your database timestamps are standard UTC-based Unix timestamps.

You should also check your system's time and timezone settings; your computer may be treating GMT as local time (and its clock could be several hours off).

edited Jun 25, 2012 at 16:38

answered Jun 25, 2012 at 16:31

Keith Thompson

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2 Comments

Greg Dickinson Over a year ago

You're absolutely right, the stamps in the DB are in the proper Unix timestamp format. After reading Russellds' answer above I realized that the actual issue is, is that PowerShell is taking my local system time (which is in the correct Time Zone per the Control Panel) and converting it directly to "number of seconds since 1/1/70" without first changing local time to GMT. You then get a timestamp that is assumed to be in GMT but is not :)

phuclv Over a year ago

@GregDickinson that's a bug in PowerShell 5.1. I've checked in PowerShell Core 7.x and see that it's been fixed

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