Formatting Date Strings with PowerShell

Summary: Microsoft Scripting Guy, Ed Wilson, talks about formatting date strings with Windows PowerShell.

Microsoft Scripting Guy, Ed Wilson, is here. It seems that different ways to display dates and times are in great supply. In fact, there are dozens of ways to do this. If I decide that I do not like the way a date or time displays, I can change it. In addition, the way a particular date style displays in one country is different than the way it displays in another country.

These differences are part of the culture settings. For example, the output from the Get-Date cmdlet appears differently depending on the UI culture settings. Here is an example:

PS C:\> Use-Culture de-de {get-date}

Mittwoch, 21. Januar 2015 12:23:40

PS C:\> Get-Date

Wednesday, January 21, 2015 12:23:45 PM

   Note  The Use-Culture function is not standard in Windows PowerShell or Windows. It comes from Lee Holmes’  
   PowerShell Cookbook module. I installed it from the PowerShell Gallery, but it is also available on PoshCode.

In general, I want the date to automatically change the way it displays based on culture settings because it helps avoid confusion. There may be times when I want to override this behavior. I can do this by directly formatting the date. I can use the ToStringmethod and specify the display pattern. The pattern MM – dd –yyyy specifies that I want the month, day, and year to appear in that order. The MM is case sensitive. Here is an example:

PS C:\> (Get-Date -Month 2 -Day 12 -Year 2015).tostring("MM-dd-yyyy")

02-12-2015

There can be a very real problem with this technique. In many regions, the day value comes first. So is the month February or is it December? Here is how the date displays when I use German UI culture settings:

PS C:\> Use-Culture de-DE {(Get-Date -Month 2 -Day 12 -Year 2015).tostring("MM-dd-yyyy")}

02-12-2015

According to their pattern, this is December 2, 2015. Here is the short date pattern:

PS C:\> [System.Globalization.CultureInfo]::GetCultureInfo(1031).DateTimeFormat.ShortDatePattern

dd.MM.yyyy

Now the culture settings use a hexadecimal value from the National Language Support API. Germany uses a hex value of 0x0407. If I convert it to a decimal format, it becomes 1031. This is shown here:

PS C:\> 0x0407

1031

I double check that I have the correct language settings by using the GetCulturalInfo static method:

PS C:\> [System.Globalization.CultureInfo]::GetCultureInfo(1031)

LCID             Name             DisplayName                                                    

----                 ----                  -----------                                                     

1031             de-DE            German (Germany)      

So if I really want to display a short date, I need to use a format specifier to tell Windows PowerShell to display a short date. In this way, it will be culture specific. On the MSDN page, Standard Date and Time Format Strings, I learn that the .NET short date specifier is “d”. So, I use the –format parameter of Get-Date, and the following appears:

PS C:\> get-date -Format d

1/21/2015

But what about using a different culture? Well, this is how it displays in culture de-DE:

PS C:\> Use-Culture de-DE {get-date -Format d}

21.01.2015

As a best practice, I should avoid creating my own date format strings if at all possible. If I use the built-in .NET date format specifiers, Windows PowerShell automatic displays it in the correct format. Here is a table of the .NET date format specifiers.

That is all there is to using .NET date format specifiers. Date Time Week will continue tomorrow when I will talk about more cool stuff.

I invite you to follow me on Twitter and Facebook. If you have any questions, send email to me at scripter@microsoft.com, or post your questions on the Official Scripting Guys Forum. See you tomorrow. Until then, peace.

Ed Wilson, Microsoft Scripting Guy