Problem
You want to control the way that PowerShell displays or formats a date.
Solution
To control the format of a date, use one of the following options:
• The GetDate cmdlet’s –Format parameter:
PS >GetDate Date "05/09/1998 1:23 PM" Format "ddMMyyyy @ hh:mm:ss" 09051998 @ 01:23:00
• PowerShell’s string formatting (f) operator:
PS >$date = [DateTime] "05/09/1998 1:23 PM" PS >"{0:ddMMyyyy @ hh:mm:ss}" f $date 09051998 @ 01:23:00
• The object’s ToString() method:
PS >$date = [DateTime] "05/09/1998 1:23 PM" PS >$date.ToString("ddMMyyyy @ hh:mm:ss") 09051998 @ 01:23:00
• The GetDate cmdlet’s –UFormat parameter, which supports Unix date format strings:
PS >GetDate Date "05/09/1998 1:23 PM" UFormat "%d%m%Y @ %I:%M:%S" 09051998 @ 01:23:00
Discussion
Except for the –Uformat parameter of the GetDate cmdlet, all date formatting in PowerShell uses the standard .NET DateTime format strings. These format strings let you display dates in one of many standard formats (such as your system’s short or long date patterns), or in a completely custom manner.
If you are already used to the Unixstyle date formatting strings (or are converting an existing script that uses a complex one), the –Uformat parameter of the GetDate cmdlet may be helpful. It accepts the format strings accepted by the Unix date command, but does not provide any functionality that standard .NET date formatting strings cannot.
When working with the string version of dates and times, be aware that they are the most common source of internationalization issues—problems that arise from running a script on a machine with a different culture than the one it was written on. In North America “05/09/1998” means “May 9, 1998.” In many other cultures, though, it means “September 5, 1998.” Whenever possible use and compare DateTime objects (rather than strings) to other DateTime objects, as that avoids these cultural differences. Example 56 demonstrates this approach.
Example 56. Comparing DateTime objects with the gt operator
PS >$dueDate = [DateTime] "01/01/2006" PS >if([DateTime]::Now gt $dueDate) >> { >> "Account is now due" >> } >> Account is now due
PowerShell always assumes the North American date format when it interprets a DateTime constant such as [DateTime] "05/09/1998". This is for the same reason that all languages interpret numeric constants
(such as 12.34) in the North American format. If it did otherwise, nearly every script that dealt with dates and times would fail on international systems.
For more information about the GetDate cmdlet, type GetHelp GetDate.
