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Removing duplicate files with PowerShell

2019-12-02 22:02

Well, I finally decided to clean up the files from my storage drive.

I found a lot of duplicate files unnecessarily taking up my storage space. As looking through every single file on your hard disk is a tedious job, I wrote a little PowerShell script to assist me with that.

[CmdletBinding()]
param (
    [Parameter()]
    [string]
    $dir
)
if (!$dir) {
    $dir = Get-Location
};

class File {
    [string]$Hash
    [string]$FileName
};
class Duplicate {
    [string]$Orig
    [string]$Dupe
};

$files = @()
foreach ($file in Get-ChildItem -Path $dir -Recurse -File | Select-Object -ExpandProperty FullName) {
    $f = [File]::new()
    $f.FileName = $file
    $f.Hash = Get-FileHash -Path $file -Algorithm "SHA1" | Select-Object -ExpandProperty Hash
    $files += $f
}

$dupes = @()
for ($i = 0; $i -lt $files.Count; $i++) {
    for ($j = $i; $j -lt $files.Count; $j++) {
        if ($files[$i].Hash -eq $files[$j].Hash -And $files[$i].FileName -ne $files[$j].FileName) {
            $f = [Duplicate]::new()
            $f.Orig = $files[$i].FileName
            $f.Dupe = $files[$j].FileName
            $dupes += $f
        }
    }
}

# print the file names
$dupes

This script calculates a checksum for every file in the directory, recursively passing through every folder inside the dir it was launched at (it accepts the target through the first command line parameter as well).

As you might want to inspect the files before deleting them, this script simply prints their names to the standard output. For a quick oneliner that would purge every duplicate file found automatically, issue:

PS > Remove-Duplicates.ps1 C:\Some\Path | Select-Object -ExpandProperty Dupe | Remove-Item