Cycle through sub-folders to rename files in Powershell - powershell

Question

I have a file directory that contains many folders within it. Inside each of these sub-folders, I have a variety of files. I would like to go through each file, rename some of the items, and add extensions to some of them. I am using Powershell to do this.
I have file names with "." that all need to be replaced with "_" for example, "wrfprs_d02.03" should be "wrfprs_d02_03". I was able to successfully do that in one folder with the following code:
dir | rename-item -NewName {$_.name -replace "wrfprs_d02.","wrfprs_d02_"}
After, I make those replacements, I want to add .grb extensions on to some of the files, which all happen to start with "w", and I was able to do that within one folder with:
Get-ChildItem | Where-Object {$_.Name -match "^[w]"} | ren -new {$_.name + ".grb"}
When I step back from one folder and try to do it iteratively within many folders, my code doesn't work. I am in a directory called "Z:\Windows.Documents\My Documents\Test_data\extracted" which contains all my sub-folders that I want to iterate over. I am using the following code:
$fileDirectory = "Z:\Windows.Documents\My Documents\Test_data\extracted"
foreach($file in Get-ChildItem $fileDirectory)
{
dir | rename-item -NewName {$_.name -replace "wrfprs_d02.","wrfprs_d02_"}
Get-ChildItem | Where-Object {$_.Name -match "^[w]"} | ren -new {$_.name + ".grb"}
}
Any ideas on what my problem is?

Answer 1

because you $_ is replaced into loop when you use pipe. I propose you a new code:
$fileDirectory = "Z:\Windows.Documents\My Documents\Test_data\extracted"
Get-ChildItem $fileDirectory -recurse -file -filter "*.*" |
%{
#replace . by _
$NewName=$_.Name.Replace(".", "_")
#add extension grb if name start by w
if ($NewName -like "w*") {$NewName="$NewName.grb"}
#Add path file
$NewName=Join-Path -Path $_.directory -ChildPath $NewName
#$NewName
#rename
Rename-Item $_.FullName $NewName
}

Answer 2

Not sure what error you were getting, but using rename-item can be finicky. Or at least so in my experience.
I used the follow without issue. My files names were different so I replaced all periods with underscores. If the file starts with "W" then it changed the extension for that file.
$FilePath = Get-ChildItem "Z:\Windows.Documents\My Documents\Test_data\extracted" -Recurse -File
foreach ($file in $FilePath)
{
$newName = $file.Basename.replace(".","_")
$New = $newName + $file.Extension
if($file.Name -match "^[w]")
{
Rename-Item $file.FullName -NewName "$($New).grb"
}
else
{
Rename-Item $file.FullName -NewName $New
}
}
Hope that helps.