Powershell replacing filenames with parent folder name without changing file endings

Question

I have a parent folder with over 1000 level 1 nested folders and thousands of text files inside each folder:

Parent folder ==> Folder1 ==> File1.txt
Parent folder ==> Folder1 ==> File2.txt
Parent folder ==> Folder1 ==> File3.txt
Parent folder ==> Folder2 ==> File1.txt
Parent folder ==> Folder2 ==> File2.txt
Parent folder ==> Folder2 ==> File3.txt
Parent folder ==> Folder3 ==> File1.txt
Parent folder ==> Folder3 ==> File2.txt
Parent folder ==> Folder3 ==> File3.txt

I need to be able to rename the files with PowerShell as follows:

Parent folder ==> Folder1 ==> Folder1_File1.txt
Parent folder ==> Folder1 ==> Folder1_File2.txt
Parent folder ==> Folder1 ==> Folder1_File3.txt
Parent folder ==> Folder2 ==> Folder2_File1.txt
Parent folder ==> Folder2 ==> Folder2_File2.txt
Parent folder ==> Folder2 ==> Folder2_File3.txt
Parent folder ==> Folder3 ==> Folder3_File1.txt
Parent folder ==> Folder3 ==> Folder3_File2.txt
Parent folder ==> Folder3 ==> Folder3_File3.txt

Is there a way of doing this in PowerShell, Windows Server 2012

Thank you ahead of time.

Answer 1

dir C:\temp\folder\ -directory | % {dir $_.fullname | % {ren $_.fullname $((split-path (split-path $_.fullname) -leaf) + '_' + $_.name)}}