PowerShell Tip: Bulk Appending File Extensions with One-Liner Magic

Ever found yourself staring at a folder full of files and wishing you could batch append them all with a .txt suffix? PowerShell makes this delightfully simple with a one-liner:

Get-ChildItem -File | Rename-Item -NewName {$_.Name + '.txt'}

To expand further to include files in all sub folders, use below instead.

Get-ChildItem -File -Recurse | Rename-Item -NewName { $_.Name + '.txt' }

If you wish to rollback what you just did, use the following:

Get-ChildItem -Path . -Recurse -File -Filter "*.txt" | ForEach-Object {
    $newName = [System.IO.Path]::GetFileNameWithoutExtension($_.Name)
    Rename-Item -Path $_.FullName -NewName $newName
}

Feel free to replace the txt with a different one based on your needs!