I’m trying to rename some csv files using Regex and I’m getting incorrect output. I’m losing the file extension and the variable I’m trying to include as a prefix in the regex is going in as a literal. Intended results, actual results, and code below:

Incoming files

d:files9001.001 (2).csv

d:files9001.004.csv

d:files9002.006 (3).csv

d:files9002.007 (2).csv

d:files9002.008 (2).csv

Desired output

d:filesDB17-9001-001.csv

d:filesDB17-9001-004.csv

d:filesDB17-9002-006.csv

d:filesDB17-9002-007.csv

d:filesDB17-9002-008.csv

Actual Output

d:files$prefix-9001-001

d:files$prefix-9001-004

d:files$prefix-9002-006

d:files$prefix-9002-007

d:files$prefix-9002-008

Code

$folder_input="d:files" $prefix="DB17" Get-ChildItem $folder_input*.csv| Foreach-Object { Rename-Item $_ ($_.BaseName -replace "^.*?([0-9]{4}).([0-9]{3})[ ].*" ,'$prefix-$1-$2') }