PowerShell Import-Module vs Dot Sourcing

powershell import-module
RinoTom picture RinoTom · Feb 14, 2013 · Viewed 19.3k times · Source

If I want to separate out some of my functionality from my main PowerShell script, I can either write that as a .ps1 file and dot source the same or I can create that as a .psm1 and import the same using Import-Module.

Which one is better and why?

Answer

Keith Hill picture Keith Hill · Feb 14, 2013

Modules are best for libraries. They give you more control over what is exported from the module. That is by default all script variables in a PSM1 file are private - not visible outside the module when it's imported. Likewise, all functions are public. However, you can use Export-ModuleMember in your PSM1 file to control exactly what variables, functions, aliases, cmdlets, etc that you export from your module. Modules can also be removed from your session which is a major difference with dotsourcing a .PS1 script. Another difference is that module functions are namespaced by the module they're in so you can easily access identically named module-based functions by prefixing the module name and a "\" to the function name e.g. PSCX\Get-Uptime. In ISE, this prefix also invokes intellisense support.

I generally recommend going with modules. :-)

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