August 6, 2008 / by Jeffery Hicks / Books and Training, Windows PowerShell / 2 Comments

Touch This

One of the last tasks for the Active Directory Powershell book was to assemble all the script samples. When the book is available you’ll be able to download a zip file from SAPIENPress.com. One thing I wanted to do was to use the file time stamp as a versioning tool.

This is pretty easy to do by modifying the CreationTime property among others. I put together a simple function called Touch-File. The function takes a filename and datetime as parameters. Even though the function will likely be used in a pipeline, I wanted to add some code to verify the file exists.

$file=Get-Item $path -ea “silentlycontinue”

By setting the -errorAction parameter to silentlyContinue, PowerShell will continue in the event the file doesn’t exist. Then I can use an If statement to see if $file has a value.

if ($file) {
        Write-Host “Touching $path” -foregroundcolor Green

Once I know the file exists, I can easily change the CreationTime properties, among others:

$file.CreationTime=$touch

Here’s a script I used to update all my AD scripts that puts this function to work.

   1: #Touch-File.ps1
   2:  
   3: Function Touch-File {
   4:     Param([string]$path=$(Throw "You must specify the name of a file"),
   5:           [datetime]$touch=(Get-Date)
   6:           ) 
   7:  
   8:     #properties to change
   9:  
  10:     [datetime]$UTCTime=$touch.ToUniversalTime()
  11:     
  12:     $file=Get-Item $path -ea "silentlycontinue"
  13:     if ($file) {
  14:         Write-Host "Touching $path" -foregroundcolor Green
  15:         $file.CreationTime=$touch
  16:         $file.CreationTimeUtc=$UTCTime
  17:         $file.LastAccessTime=$touch
  18:         $file.LastAccessTimeUtc=$UTCTime
  19:         $file.LastWriteTime=$touch
  20:         $file.LastWriteTimeUtc=$UTCTime
  21:     }
  22:     else {
  23:         Write-Warning "Failed to find $path"
  24:         
  25:     }
  26:  
  27: }
  28:  
  29: dir c:\scripts\posh\ad\*.ps1 | foreach {
  30:   Touch-File $_ "8/1/2008 01:00:00"
  31:   }

Every file in C:\scripts\posh\ad is sent to the Touch-File function that sets the file date to “8/1/2008 01:00:00”. Not sure if you have a need for a function like this but I like to share.

Download my sample script here.

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