{"id":206,"date":"2021-02-26T04:15:49","date_gmt":"2021-02-26T12:15:49","guid":{"rendered":"https:\/\/devblogs.microsoft.com\/powershell-community\/?p=206"},"modified":"2021-02-27T09:33:02","modified_gmt":"2021-02-27T17:33:02","slug":"getting-yesterdays-date","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/powershell-community\/getting-yesterdays-date\/","title":{"rendered":"Getting Yesterday’s Date"},"content":{"rendered":"

Q:<\/strong> How can I get yesterday’s date?<\/p>\n

A:<\/strong> You can use a combination of the Get-Date<\/code> cmdlet and .NET Time\/Date methods.<\/p>\n

First, let’s look at dates in PowerShell and .NET Then we can look at how to calculate yesterday and use that in your scripts.<\/p>\n

Dates in PowerShell<\/h2>\n

Let’s start by looking at how you can deal with dates and times. As you probably know, PowerShell contains the Get-Date<\/code> cmdlet. This cmdlet returns a .NET System.DateTime<\/strong> object.<\/p>\n

Using the Get-Date<\/code> cmdlet, you can get any date and time, and either display it or store it in a variable. To get today’s date. you could do this:<\/p>\n

PS C:> # Get the current date\nPS C:> Get-Date\n08 January 2021 11:24:46\n\n# Store the date in a variable\n$Now = Get-Date\n$Now\n08 January 2021 11:24:47\n<\/code><\/pre>\n
As mentioned, the Get-Date<\/code> cmdlet returns an object whose type is System.DateTime<\/strong>. This .NET structure provides a rich set of properties and methods to help you manipulate the date\/time object. See the System.DateTime documentation<\/a> for more details on this structure. A date and time object contains both a date and a time. This means you can create an object with just a date or just a time, or both, which gives you huge flexibility in handling dates and times.<\/p>\n
If you run Get-Date<\/code> and specify no parameters, the cmdlet returns the current date and time. There are several parameters you can specify that allow you to create an object for a particular date, like this:<\/p>\n
PS C:> # Using the -Date Parameter and a date string\nPS C:> Get-Date -Date '1 August 1942'\n01 August 1942 00:00:00\n\n# Using the -Month, Day, Year to be specific and avoid parsing\nPS C:> Get-Date -Month 8 -Day 1 -Year 1942 -Hour 0 -Minute 0 -Second 0\n01 August 1942 00:00:00\n<\/code><\/pre>\n
You can see the other features of Get-Date<\/code> to help get the date in the exact format you need, see the Get-Date<\/code> help information<\/a>.<\/p>\n
Obtaining Yesterday’s Date<\/h2>\n
So as you can see, you can use Get-Date<\/code> to return a specific date\/time. So how do you get yesterday’s date – or the date or last month or last year? The trick here is to use the object returned from Get-Date<\/code>. The object has a type of System.DateTime<\/code> which contains a number of methods allowing you to add increments of time – a month, a day, etc to the object.<\/p>\n
To get yesterday’s date (or tomorrow’s) you create a date and time object for today using Get-Date<\/code> with no parameters. Then you use the AddDays()<\/code> method to add\/subtract some number of days, like this:<\/p>\n
PS C:> # Get today's Date\nPS C:> $Today     = Get-Date\nPS C:> $Yesterday = $Today.AddDays(-1)\nPS C:> $Yesterday\n19 February 2021 12:13:51\n\nPS C:> # Or more simply\nPS C:> $Yesterday = (Get-Date).AddDays(-1)\nPS C:> $Yesterday\n19 February 2021 12:13:52\n\nPS C:> # Get tomorrow's date\nPS C:> $Tomorrow  = (Get-Date).AddDays(1)\nPS C:> $Tomorrow\n21 February 2021 12:13:54\n<\/code><\/pre>\n
It is worth noting that a System.DateTime<\/code> object is immutable. This means you can not change property values after you create the object. If you use any of the Add<\/code> methods, .NET returns a new object with updated property values.<\/p>\n
Using Yesterday’s Date<\/h2>\n
There are a variety use cases for getting a date in the past (or the future), including:<\/p>\n