Batch rearranging and renaming filenames in PowerShell - powershell

Question

I need help with rearranging and renaming a bunch of files in PowerShell.
I want to change from:
YYYY_Project name_City_Category.jpg
to
YYYY_Category_Project name_City.jpg
The years, categories, project names and cities are of course all different.
Please be gentle, I'm new to PowerShell and regex.

Answer 1

Assuming we have an item like this:
get-item '.\YYYY_Project name_City_Category.jpg'
Directory: C:\temp
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a---- 6/8/2020 10:12 AM 8 YYYY_Project name_City_Category.jpg
This is a FileInfo object which has a number of properties, one of which is BaseName which gives us the filename without extension.
PS> $file = get-item '.\YYYY_Project name_City_Category.jpg'
PS> $File.BaseName
YYYY_Project name_City_Category
We can call the .Split() method on the BaseName property to split on every instance of the _ underscore character, like so:
PS> $File.BaseName.Split('_')
YYYY
Project name
City
Category
We can then assign those to variables like this:
$FileSegments = $File.BaseName.Split('_')
$YearPart = $FileSegments[0]
$ProjPart = $FileSegments[1]
$CityPart = $FileSegments[2]
$CatgPart = $FileSegments[3]
We can then reassemble them in our desired order like this:
$newName = $YearPart + "_" + $CatgPart + "_" + $ProjPart + "_" + $CityPart + $file.Extension
write-host $newName
YYYY_Category_Project name_City.jpg
So, you'd put it all together like this. If you like the results, remove -WhatIf
$files = Get-ChildItem C:\PathTo\Your\Directory\*.jpg
ForEach ($file in $files){
$FileSegments = $File.BaseName.Split('_')
$YearPart = $FileSegments[0]
$ProjPart = $FileSegments[1]
$CityPart = $FileSegments[2]
$CatgPart = $FileSegments[3]
$newName = $YearPart + "_" + $CatgPart + "_" + $ProjPart + "_" + $CityPart + $file.Extension
write-host $newName
Rename-Item -Path $file.FullName -NewName $newName -WhatIf
}

Answer 2

You don't need a complex Regex for this, just some understanding of how to get the files in a folder using Get-ChildItem and how Rename-Item works.
Something like this should do it
$sourcePath = 'Folder\To\Where\The\Files\Are'
Get-ChildItem -Path $sourcePath -Filter '*.jpg' -File | Rename-Item -NewName {
# split the file's BaseName into 4 pieces at the underscore
$year, $project, $city, $category = $_.BaseName -split '_', 4
# use the -f Format operator to stitch the parts together in a new order
# see https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_operators?view=powershell-5.1#format-operator--f
'{0}_{1}_{2}_{3}{4}' -f $year, $category, $project, $city, $_.Extension
}

Answer 3

One liner version of the split and join idea:
dir *_*_*_*.jpg | ren -new {((($_.basename -split '_')[0,3,1,2]) -join '_') +'.jpg'} -whatif
What if: Performing the operation "Rename File" on target
"Item: C:\Users\admin\foo\YYYY_Project name_City_Category.jpg
Destination: C:\Users\admin\foo\YYYY_Category_Project name_City.jpg".