I've been using Powershell to simplify repetitive tasks in creating directories, renaming and moving files. I'm working with Video and PDF files where the required syntax of the filename is very specific. So far I've been able to correct all of the common errors I run across, but this one has me stumped.
The correct syntax for my files would include:
01A-50_02A-50-CIPP-PRE.MP4
01AA-50_02AA-50-CIPP-PNSL.PDF
W01AA-48_02AA-48-CIPP-PST-CMP.MPG
I'm receiving a large amount of files that look like this:
01A-50-02A-50-CIPP-PRE.MP4
01AA-50-02AA-50-CIPP-PNSL.PDF
W01AA-48-02AA-48-CIPP-PST-CMP.MPG
I need to replace the second dash with an underscore while keeping the other dashes unaffected. I can otherwise do this in bulk with some help from excel, but I was hoping to have a short code that could find and correct this error in syntax without having to export a list to excel, use text to columns, and then concatenate the alphanumeric portions back together. I also don't want to correct all these filenames manually.
From what I've researched, it's not possible to target a specific occurrence of a character to replace. the closest I've come to thinking I'd found a solution involved REGEX and identifying and replacing a pattern. I haven't been able to do anything constructive with that.
The way I would use this code would be by opening the folder that contains the missnamed files, opening a Powershell window there, copying the code from a txt file on my desktop, and pasting it into Powershell.
Any help on this would be greatly appreciated.
Use the -replace operator with a regular expression:
Get-ChildItem |
Rename-Item -NewName { $_.Name -replace '^([^_-]+-[^_-]+)-', '$1_' } -WhatIf
-WhatIf previews the renaming operation; remove it to perform actual renaming.
Regex '^([^_-]+-[^_-]+)-' captures the first two - separated tokens at the start (^) of the filename, using a capture group ((...)) to capture the tokens excluding the 2nd -.
[^_-]+ captures any nonempty run of characters that are neither - nor _. _ is also ruled out in order to prevent false positives with filenames that already are correct; for those, not ruling out _ would match the first 3 tokens and insert an additional _ there.Replacement operand $1_ then uses the value of the 1st (and only) capture group ($1) followed by a literal _ to replace what the regex matched, which effectively replaces the 2nd - with a _.
If a given file name doesn't match the regex (if it already is correct), the name is returned as-is, which is a quiet no-op in the context of Rename-Item.