Using PowerShell to add an extension to files

Question

I have a directory of files that I'd like to append file extension to as long as they don't have an existing, specified extension. So add .txt to all file names that don't end in .xyz. PowerShell seems like a good candidate for this, but I don't know anything about it. How would I go about it?

Answer 1

Here is the Powershell way:

gci -ex "*.xyz" | ?{!$_.PsIsContainer} | ren -new {$_.name + ".txt"}

Or to make it a little more verbose and easier to understand:

Get-ChildItem -exclude "*.xyz" 
    | WHere-Object{!$_.PsIsContainer} 
    | Rename-Item -newname {$_.name + ".txt"}

EDIT: There is of course nothing wrong with the DOS way either. :)

EDIT2: Powershell does support implicit (and explicit for that matter) line continuation and as Matt Hamilton's post shows it does make thing's easier to read.

Answer 2

+1 to EBGreen, except that (at least on XP) the "-exclude" parameter to get-childitem doesn't seem to work. The help text (gci -?) actually says "this parameter does not work properly in this cmdlet"!

So you can filter manually like this:

gci 
  | ?{ !$_.PSIsContainer -and !$_.Name.EndsWith(".xyz") } 
  | %{ ren -new ($_.Name + ".txt") }