How to validate PowerShell to check if a file exists

PowerShell scripts often rely on the presence of specific files. If a file is missing, the script may throw an error message and stop execution. Instead of guessing or silencing PowerShell errors, you can use Test-Path to check if the file exists before taking action.

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How does Test-Path prevent PowerShell script errors?

Say you need to remove a sensitive file across several machines but don’t know where it exists. If you try accessing the file directly and it’s missing, PowerShell will throw an error. PowerShell Test-Path lets you check first — avoiding those failures.

To test this, let us use the probably-not-true scenario of me copying my Social Security number to several computers on a drunken dare. Upon sobering up, I want to correct this, but I have no idea which machines I put the information on. This is time sensitive, so I don’t want to go to each machine and test it individually, but I need to check every machine and remove the file if it exists.

If I attempt to grab the file and am wrong about its existence, I will fail with the following error:

PowerShell error from Get-ChildItem showing failure to find file path C:\temp\JordansSocial.txt

Test-Path is not trying to return with the object, so it just returns whether the file exists.

PowerShell Test-Path command returning False for missing file C:\Temp\JordansSocial.txt

With no error, we do not have to worry about our script just stopping if the file does not exist. Instead, it opens a few possibilities.

How do I copy a file to a machine if it’s missing?

If the specific file doesn’t exist, you can use Copy-Item to add it before continuing the script. The exclamation point in the following script tells it to proceed if Test-Path returns a false value.

if(!(Test-Path -Path C:\Temp\JordansSocial.txt)){
    Copy-Item "\\RealFileServer\CriticalFiles\JordansSocial.txt" -Destination "C:\temp\Jordanssocial.txt"
}

This script is of immense value if an install or custom software requires a certain file to work. It allows you to make sure everything you need for a script to succeed is present before continuing. In my situation, this is a worst-case scenario, as it checks a computer and copies over my private information if it wasn’t already there. This is just compounding my issue.

How do I delete a file if it’s present?

What I am looking for is to delete the item if it exists and give me a nice message if it does not.

$JordansShame = "C:\Temp\JordansSocial.txt"
if(Test-Path -Path $JordansShame){
    Remove-Item $JordansShame
}Else{
    Write-Host "It turns out your stupidity does know SOME bounds"
}

Problem solved … assuming I named the file the same thing. I can’t be sure I did, and we need to protect my super sweet 375 credit score. It is time to flex some of the versatility of Test-Path.

How do I remove recently created files in PowerShell?

To find recently created files, define the time window and use Test-Path with Get-ChildItem to locate and remove files from a known directory.

In our example:

We know I started drinking 11 hours ago.
I lack creativity and always copy files into C:\temp. I have six years of webcasts backing this up.

Knowing this, I need a script to look in C:\temp for any file that was created within the last 11 hours and remove it.

$date = (Get-Date).AddHours(-11)
$JordansShame = “C:\Temp\”
if(!(Test-Path -Path $JordansShame -NewerThan $date)){
    Write-Host "No new files created within the last 11 hours"
}else{
    Get-ChildItem $JordansShame | Where-Object{$_.LastWriteTime -gt $date} | Remove-Item
}

Combine this script with Invoke-Command, and we can clear out my mistake from every computer.

$computers =  "Billy.whiskeytime.club","Demogorgon.whiskeytime.club","Dustin.whiskeytime.club","Eddie.whiskeytime.club","Eleven.whiskeytime.club","Hopper.whiskeytime.club"
$cred = Get-Credential
$script = {
    $date = (Get-Date).AddHours(-11) 
    $JordansShame = "C:\temp\"
    if(!(Test-Path -Path $JordansShame -NewerThan $date)){ 
        Write-Host "No new files created within the last 11 hours on $(hostname)" 
    }else{ 
        Write-Host "Deleting files from $(hostname)"
        Get-ChildItem $JordansShame | Where-Object{$_.LastWriteTime -gt $date} | Remove-Item 
    }
}
Invoke-Command -ComputerName $computers -ScriptBlock $script -Credential $cred

PowerShell output from Invoke-Command showing conditional file deletion based on creation time across multiple remote computers.

It is funny — I spent all of this time creating a fake scenario to showcase Test-Path, and to build the scenario, Test-Path was needed to make sure I had a C:\Temp on every machine. My script to make this happen looked like this.

If(!(test-path C:\temp)){
    New-Item c:\temp -ItemType Directory -Force
}
New-Item C:\temp\JordansSocial.txt

All of that work to generate a scenario, and valid examples just fall from the sky. Anyway, crisis averted. I need a drink.