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PowerShell Compare Dates

PowerShell Get-Date cmdlet returns the DateTime object. To Compare dates in PowerShell, use the PowerShell operator lt or gt. It compares the date is less or greater than the other date.

PowerShell Compare date to current date
PowerShell Compare date to current date

In PowerShell, Get-Date returns the DateTime object, hence comparison of the dates becomes much easier with the PowerShell operator lt or gt.

You can compare date strings in PowerShell provided they are in the correct DateTime format.

In this article, we will discuss how to compare dates in PowerShell and compare date strings in PowerShell.

PowerShell Compare Dates

Use the PowerShell operator like lt ( lesser than) or gt ( greater than) to compare two dates in PowerShell.

Let’s use an example to compare two timestamps in PowerShell.

# Get Current Date
$date1 = Get-Date 

# Get Previous Date
$date2 = (Get-Date).AddDays(-1) 

# Compare two dates, if $date1 is less than $date2
$date1 -lt $date2

# Compare two dates, if $date1 is greater than $date2
$date1 -gt $date2  

In the above PowerShell script, Get-Date returns the current DateTime object and stores it in $date1 variable. $date2 variables store the previous day’s date.

We have used -lt operator to check if $date1 is lesser than $date2 and it returns a boolean value as False

-gt operator used to check if $date1 is greater than $date2 returns a boolean value as True. It means $date1 is greater than $date2.

The output of the above PowerShell to compare two dates using the PowerShell operator lt and gt are as given below:

PowerShell Compare Dates
PowerShell Compare Dates

PowerShell Compare Date Strings

In PowerShell to compare date strings, strings that need to be compared against the date should have the correct date format else it will throw an exception while comparing two date strings.

# Get the current date of the user login
$loginDate = Get-Date 

# User account expiry date
$accountexpiryDate ="02-25-2023"

# Compare date strings
$loginDate -lt $accountexpiryDate    

In the above PowerShell script, $loginDate variable stores the current DateTime object. $accountexpiryDate variable stores the date in string format.

While comparing the dates, use the PowerShell operators like lt or gt to check if a date is less or greater than a later one, it returns the boolean value either True or False.

In the above script, the date in string format follows the system format, which means on my machine, the DateTime format is “mm-dd-yyyy“, hence date time comparison with string is possible.

The output of the above PowerShell to compare two dates is given below

PS C:\Windows> $loginDate = Get-Date                                                                                    PS C:\Windows> $loginDate                                                                                               
21 January 2023 18:45:59


PS C:\Windows> $accountexpiryDate ="02-25-2023"                                                                         PS C:\Windows> $accountexpiryDate                                                                                       02-25-2023

PS C:\Windows> $loginDate -lt $accountexpiryDate                                                                        True
PS C:\Windows> 

If we modify the $accountexpiryDate to “25-02-2023” ( dd-mm-yyyy), it would result in the exception “String was not recognized as a valid DateTime” as given below

PS C:\Windows> $accountexpiryDate ="25-02-2023"    

PS C:\Windows> $loginDate -lt $accountexpiryDate

Could not compare "01/21/2023 18:45:59" to "25-02-2023". Error: "Cannot convert value "25-02-2023" to type
"System.DateTime". Error: "String was not recognized as a valid DateTime.""
At line:1 char:1
+ $loginDate -lt $accountexpiryDate
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : ComparisonFailure

PS C:\Windows>   

Conclusion

I hope the above article on how to compare two dates in PowerShell is helpful to you.

PowerShell operator lt and gt are used to compare dates and returns a boolean value.

You can find more topics about PowerShell Active Directory commands and PowerShell basics on the ShellGeek home page.

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