If you've been using powershell for any period of time, you'd get used to the idea that it doesn't really care about casing. PowerCLICore on Docker ? Yeah, it's a casing nazi...sometimes. Now this experience was seen on a Mac. Unsure if Docker running on linux sees this. When working w/ cmdlets in general, you should fine. However, if you were to query for commands related to a specific module like pester: You'd get a blank return. Looking at modules available via: get-module -listavailable Will show that pester is capitalized as "Pester" so valid get-command is: get-command -module Pester Long story short, if you are having issue running a script or whatnot, be sure to check your cAsInG. Interestingly, once you do a get-command -module Pester successfully, powerclicore on docker magically doesn't care about casing after the fact.