Use Regex / Powershell to rename files

Question

How does one rename the following files (New => Old):

filename__Accelerated_C____Practical_Programming_by_Example.chm -> C Practical Programming by Example.chm

filename__Python_Essential_Reference__2nd_Edition_.pdf -> Python Essential Reference 2nd Edition.pdf

filename__Text_Processing_in_Python.chm -> Text Processing in Python.chm

Answer 1

Try this one:

Get-ChildItem directory `         | Rename-Item -NewName { $_.Name -replace '^filename_+','' -replace '_+',' ' } 

Note that I just pipe the objects to Rename-Item, it is not really needed to do it via Foreach-Object (alias is %).

Update

I haven't anything documented about the 'magic' with scriptblocks. If I remember correctly, it can be used if the property is ValueFromPipelineByPropertyName=$true:

function x{     param(         [Parameter(ValueFromPipeline=$true)]$o,         [Parameter(ValueFromPipelineByPropertyName=$true)][string]$prefix)     process {         write-host $prefix $o     } } gci d:\ | select -fir 10 | x -prefix { $_.LastWriteTime } 

Answer 2

This should work:

ls | %{ ren $_ $(($_.name -replace '^filename_+','') -replace '_+',' ') } 

Expanding the aliases and naming all argument, for a more verbose but arguably more understandable version, the following is equivalent

Get-ChildItem -Path . | ForEach-Object { Rename-Item -Path $_ -NewName $(($_.Name -replace '^filename_+','') -replace '_+',' ') }