Normalizing File Extensions

by Feb 24, 2015

PowerShell 2.0 and later

Let’s assume you want the user to submit a list of file extensions, or you are getting them from some other source.

File extensions are a perfect example of fuzzy standards. How would you specify a text file extension? Is it “.txt”, or is it “*.txt”?

Here is a simple trick that normalizes file extensions, regardless of how they were specified:

$extensions = '*.ps1', '.txt'
$cleanExtensions = $extensions -replace '^\.', '*.'

$extensions
$cleanExtensions

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