difficulty renaming batch of files with PowerShell without losing extension - powershell

Question

I am trying to use PowerShell to rename a folder containing thousands of images. I want to add both a prefix and a suffix, but this is proving more difficult than I bargained for. I don't understand PowerShell at all... and have dug around for help, and ended up with mixed results.
The best I've found was the example here: Renaming Files with PowerShell
Which yields ...
Dir -recurse | Sort {$.FullName.Length} -Desc | Rename-Item {$.Name -replace ' ','_'}
Now, I'm not wanting to replace anything, so I tried to just
Dir -recurse | Sort {$.FullName.Length} -Desc | Rename-Item { "pre-" + $.Name + "-suff" }
That gave me an error though, and I'm not quite sure how to interpret it;
Rename-Item : A positional parameter cannot be found that accepts argument ' "pre-" + $_.Name + "-suff" '.
At line:1 char:50
+ ... _.FullName.Length} -Desc | Rename-Item { "pre-" + $_.Name + "-suff" }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidArgument: (:) [Rename-Item], ParameterBindingException
+ FullyQualifiedErrorId : PositionalParameterNotFound,Microsoft.PowerShell.Commands.RenameItemCommand
I quite literally have no idea what this is trying to say. I've dug around deeper, and found this tutorial: http://blogs.technet.com/b/heyscriptingguy/archive/2013/11/22/use-powershell-to-rename-files-in-bulk.aspx
And it has some slightly different commands, so I tried to plug that in with...
Get-ChildItem -Filter "current" -Recurse | Rename-Item -NewName { "pre-" + $_.name + "-suffix" }
And I get no error, but nothing seems to happen, either. This is proving to be very frustrating, as I keep searching for answers but every page I turn up is nebulous at best. Is there a simpler way to accomplish this? I'm wanting to append the prefix and suffix without affecting the file extension.
I did find something a bit closer to what I needed at: http://social.technet.microsoft.com/wiki/contents/articles/25144.powershell-bulk-renaming-file-names.aspx
And it suggested this script,
Get-ChildItem | Where-Object { $.Extension -eq ".jpg" -or $.Extension -eq ".png"} | rename-item -newname {"CL - " + $_.Name}
Which I changed to ...
Get-ChildItem | Where-Object { $.Extension -eq ".jpg" -or $.Extension -eq ".png"} | rename-item -newname {"prefix-" + $_.Name + "-suffix" }
And that at least did something to the files, but now the suffix is appended after the extension, which is obviously not what I'm going for.

Answer 1

you are almost there :)
Get-ChildItem -Include *.jpg,*.png -Recurse |
Rename-Item -NewName { 'Prefix' + $_.BaseName + 'Suffix' + $_.Extension } -WhatIf
Notice the -whatif at the end...this switch simulates command execution...Run the code first see the whatif output and if you are satisfied with the results then run the same command above without the -whatif to execute.
the $_.name includes the filename with the extension which is why you are getting the filenames with the suffix appended to the extension.
Get-Childitem | fl * will show you what properties you can work with.