assign current time to powershell variable - powershell

Question

I pieced together a PowerShell script that is triggered (via Task Scheduler) every time the computer restarts.
The script will do the following:
Find a csv file located in a specific directory
Rename the file by appending a time/date stamp to the end
Move that file into an archive folder
During the day a software application automatically creates a new csv file. So next time the computer reboots, it repeats the steps above.
Final step - the script also looks in the archive folder and deletes any files which are > 7 days old.
Sometimes (not all the time) when the computer restarts and the script runs, it completes steps 1 and 2 but not step 3.
And so what this means is the csv file is renamed but the script did NOT move it into the archive folder.
Why?
I open the script in PowerShell ISE and run the script manually and I see the reason why:
A file with that name already exists in the archive folder.
How can that happen if the file name is always dynamically renamed using a date/time stamp (down to the second).
Turns out the variable which is assigned the value of Get-Date is not updated.
It still contains the old time.
Why does this happen if the very first thing I do in my PowerShell script is this:
$rightNow = Get-Date
I know it's not best practice to assign the current date and time to a variable and obviously the variable is not going to update itself as every second goes by. That's fine. I don't need it to. What I DO expect it to do is grab the current date and time (at the time this line of code runs) and assign it to my variable called $rightNow.
For some reason the variable is not getting updated.
Why does this happen? What's the best way for me to quickly grab the current date and time (down to the second) and use it as part of a file name?
Here is my current script:
$source = "C:\Logs"
$destination = "C:\Logs\archive"
$old = 7
$rightNow = Get-Date
# delete all files in the archive folder that are > 7 days old
Get-ChildItem $destination -Recurse |
Where-Object {-not $_.PSIsContainer -and
$rightNow.Subtract($_.CreationTime).Days -gt $old } |
Remove-Item
# rename all csv files in the Log folder by appending currentDate_currentTime
Get-ChildItem -Path $source\* -Include *.csv | % {
$name = $_.Name.Split(".")[0] + "_" + ($_.CreationTime | Get-Date -Format yyyyMMdd) + "_" + ($_.CreationTime | Get-Date -Format hhmmss) + ".csv"
Rename-Item $_ -NewName $name
Move-Item "$($_.Directory)\$name" -Destination $destination
}

Answer 1

You don't use the current date in the rename, you use the file's CreationTime property. If you want the current datetime try
$name = $_.BaseName + [datetime]::now.ToString('_yyyyMMdd_hhmmss') + $_.Extension
Or better yet just perform the rename as part of the move process.
$source = "C:\Logs"
$destination = "C:\Logs\archive"
$old = 7
# delete all files in the archive folder that are > 7 days old
Get-ChildItem $destination -Recurse -File |
Where-Object { $_.CreationTime -lt [datetime]::Today.AddDays(-$old) } |
Remove-Item
# rename all csv files in the Log folder by appending currentDate_currentTime
Get-ChildItem -Path $source\* -Include *.csv | % {
$_ | Move-Item -Dest $("$destination\" + $_.BaseName + [datetime]::now.ToString('_yyyyMMdd_hhmmss') + $_.Extension)
}