PowerShell to change "Date Modified" base on a specific date for Multiple Files-CodePudding

I am trying to change the "Date Modified" (LastWriteTime) of over 2K files in a specific folder. All files were modified on the same Day. However, it does have multiple times. So, basically what I am trying to accomplish is this:

Myfile1.Zip --> Date Modified = "1/4/2022 12:21 PM" ==> Date Modified = "1/3/2022 9:00 AM"

Myfile2.Zip --> Date Modified = "1/4/2022 12:25 PM" ==> Date Modified = "1/3/2022 9:00 AM"

Meaning that all files that were Modified on 1/4/2021 needs to display "Date Modified" as 1/3/2021, time really does not matter here.

Is it possible to do a bulk change with a PowerShell Script? I am not familiar at all with it and need this change made asap.

Thanks in Advance for your help.

CodePudding user response：

You can inspect the existing LastWriteTime property on file system objects returned by Get-ChildItem, then assign a new value to the same:

# define date/time variables
$filterDate = (Get-Date -Day 4 -Month 1 -Year 2022).Date
$targetDateTime = Get-Date -Day 3 -Month 1 -Year 2022 -Hour 9 -Minute 0 -Second 0

# locate and filter relevant files
$relevantFiles = Get-ChildItem -Path .\path\to\folder\ |Where-Object { $_.LastWriteTime.Date -eq $filterDate }

# update their timestamps
$relevantFiles |ForEach-Object {
  $_.LastWriteTime = $targetDateTime
}

Dereferencing the Date property on an existing [DateTime] value gives you the date at midnight, so the comparison $_.LastWriteTime.Date -eq $filterDate will work regardless of whether the file was updated at 1AM or 6PM, as long as it was on January 4.