Set up default date format like yyyy-mm-dd in Powershell?

Question

A simple & short question:

How can I setup a default date format in powershell like yyyy-mm-dd ? so any date output will be like this format?

or How to setup a date format globally in one script ?

Is there a way to output date only without time? when I output LastWriteTime, Default is

13-03-2014 14:51

I only need 13-03-2014, without the 14:51 part.

Answer 1

A date in PowerShell is a DateTime object. If you want a date string in a particular format, you can use the built-in string formatting.

PS C:\> $date = Get-Date
PS C:\> $date.ToString("yyyy-MM-dd")
2014-04-02

You can also use the string format (-f) operator:

PS C:\> "{0:yyyy-MM-dd}" -f $date
2014-04-02

The LastWriteTime property of a file is a DateTime object also, and you can use string formatting to output a string representation of the date any way you want.

You want to do this:

Get-ChildItem -Recurse \\path\ -filter *.pdf | Select-Object LastWriteTime,Directory

You can use a calculated property:

Get-ChildItem C:\Users\Administrator\Documents -filter *.pdf -Recurse |
  Select-Object Directory, Name, @{Name="LastWriteTime";
  Expression={$_.LastWriteTime.ToString("yyyy-MM-dd HH:mm")}}

Run

help Select-Object -Full

and read about calculated properties for more information.

Answer 2

i've used this, it works for me, just copy it at the beginning of your script

$currentThread = [System.Threading.Thread]::CurrentThread
$culture = [CultureInfo]::InvariantCulture.Clone()
$culture.DateTimeFormat.ShortDatePattern = 'yyyy-MM-dd'
$currentThread.CurrentCulture = $culture
$currentThread.CurrentUICulture = $culture

in case you'll find problem in loading assembly for CultureInfo (i had this issue on Windows 2008 Server), change line 2 in this way

$currentThread = [System.Threading.Thread]::CurrentThread
$culture = $CurrentThread.CurrentCulture.Clone()
$culture.DateTimeFormat.ShortDatePattern = 'dd-MM-yyyy'
$currentThread.CurrentCulture = $culture
$currentThread.CurrentUICulture = $culture

Answer 3

for always usage you can add in your .\Documents\WindowsPowerShell\profile.ps1

$culture = (Get-Culture).Clone()
$culture.DateTimeFormat.ShortDatePattern = 'yyyy-MM-dd'
Set-Culture $culture

Answer 4

Preface:

• There's good information in some of the existing answers:

  • Bill Stewart's helpful answer is expanded on below.

  • Mosè Bottacini answer addresses a different problem: how to redefine the current / effective culture's formatting rules in a given script (without changing when they are applied).

  • Alban's answer is an - ineffective^[1] - attempt to solve said different problem persistently, via code placed in a $PROFILE file.

• The answer below applies as of v5.1 of Windows PowerShell (the legacy, ships-with-Windows, Windows-only edition of PowerShell whose latest and final version is 5.1) as well as to PowerShell (Core) 7.

---

Ad-hoc (on-demand) formatting of dates:

Is there a way to output date only without time?

Bill Stewart's helpful answer shows you how to use .NET APIs to format [datetime] (System.DateTime) instances using custom .NET date-time format strings; let me add that you can also use standard format strings: your desired date-only, numeric-only format can be requested with d, the short date format specifier; the following calls all output the dates in that format:

Get-Date -Format d
# equivalently:
(Get-Date).ToString('d')
# equivalently:
'{0:d}' -f (Get-Date)

# In the pipeline, using simplified syntax:
# Note: % is a built-in alias of the ForEach-Object cmdlet.
(Get-Item \).LastWriteTime | % ToString d

# In the pipeline, in the context of a calculated property:
# Note: 'select' is a built-in alias of the Select-Object cmdlet.
Get-Item . | 
  select Name, @{Name='LastWriteTime';Expression={$_.LastWriteTime.ToString('d')}}

---

Default formatting of dates:

There are two formatting scenarios to consider:

• (a) When PowerShell outputs [datetime] instances directly, such as when calling Get-Date in isolation.

  • In this case, [datetime] values are represented by the rules of PowerShell's output-formatting system.

• (b) When such instances are output indirectly, as properties of enclosing objects, such as the column / list values of objects (possibly implicitly) formatted with Format-Table / Format-List

  • In this case, [datetime] values are represented by their .ToString() method return values.

The following code, adapted from this answer, covers both (a) and (b) - however, as noted there, the solution does not cover the behavior inside "..." (string interpolation):

# Override .ToString() to use the short-date format.
Update-TypeData -Force -TypeName System.DateTime -MemberType ScriptMethod -MemberName ToString -Value {
  $this.ToString('d')
}
# Redefine .DateTime, so that the formatting system uses the overridden 
# .ToString() method too.
Update-TypeData -Force -TypeName System.DateTime -MemberType ScriptProperty -MemberName DateTime -Value {
  $this.ToString() # This calls the overridden .ToString() method.
}

Also, note that these definitions persist for the remainder of the current session.

If you'd like to make this behavior the default for all future PowerShell sessions, add the code to a relevant $PROFILE file.

Caveats:

• Third-party code executed in your sessions may rely on the default formatting behavior.
• It is trivial to bypass profile processing by passing the -NoProfile switch to PowerShell on startup (via its CLIs - powershell.exe for Windows PowerShell, pwsh for PowerShell (Core) 7)

---

^{[1] (a) Due to the code in the answer not assigning the customized cloned culture to [cultureinfo]::CurrentCulture, the current session's culture remains unchanged (and even performing such an assignment will not work session-wide in Windows PowerShell, due to a bug / questionable design decision - see this answer) and (b) Set-Culture - which persistently changes the culture but only affects future sessions - does not honor customized [cultureinfo] instances passed to it: only the culture name is honored, and that culture's standard definition is made the persistent one.}