Replace or delete certain characters from filenames of all files in a folder

Use PowerShell to do anything smarter for a DOS prompt. Here, I've shown how to batch rename all the files and directories in the current directory that contain spaces by replacing them with _ underscores.

Dir |
Rename-Item -NewName { $_.Name -replace " ","_" }

EDIT :
Optionally, the Where-Object command can be used to filter out ineligible objects for the successive cmdlet (command-let). The following are some examples to illustrate the flexibility it can afford you:

• To skip any document files

  Dir |
  Where-Object { $_.Name -notmatch "\.(doc|xls|ppt)x?$" } |
  Rename-Item -NewName { $_.Name -replace " ","_" }
  

• To process only directories (pre-3.0 version)

  Dir |
  Where-Object { $_.Mode -match "^d" } |
  Rename-Item -NewName { $_.Name -replace " ","_" }
  

  PowerShell v3.0 introduced new Dir flags. You can also use Dir -Directory there.

• To skip any files already containing an underscore (or some other character)

  Dir |
  Where-Object { -not $_.Name.Contains("_") } |
  Rename-Item -NewName { $_.Name -replace " ","_" }
  

A one-liner command in Windows PowerShell to delete or rename certain characters will be as below. (here the whitespace is being replaced with underscore)

Dir | Rename-Item –NewName { $_.name –replace " ","_" }

The PowerShell answers are good, but the Rename-Item command doesn't work in the same target directory unless ALL of your files have the unwanted character in them (fails if it finds duplicates).

If you're like me and had a mix of good names and bad names, try this script instead (will replace spaces with an underscore):

Get-ChildItem -recurse -name | ForEach-Object { Move-Item $_ $_.replace(" ", "_") }