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Editorial Team
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Asked: 2026-05-12T09:51:40+00:00

I’ve just recently completed my first nightly build script (first significant anything script, really)

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I’ve just recently completed my first nightly build script (first significant anything script, really) in powershell. I seem to have things working well, if not yet robustly (I haven’t handled significant error-checking yet), but I found myself falling into an idiom around the Invoke-Expression cmdlet, and I’m wondering if I’m using it properly.

Specifically, I use a series of variables to build up command-lines that I will use to build the solution, then run the solution’s unit tests. e.g., something like:

$tmpDir = "C:\Users\<myuser>\Development\Autobuild"
$solutionPath=$tmpDir+"\MyProj\MyProj.sln"
$devenv="C:\Program Files (x86)\Microsoft Visual Studio 10.0\common7\ide\devenv"
$releaseProfile="Release"
$releaseCommandLine="`"$devenv`" `"$solutionPath`" /build `"$releaseProfile`""

This works well enough, $releaseCommandLine contains the command line that I want to execute when I’m done. I then execute it via this line:

$output = Invoke-Expression "& $releaseCommandLine"

Is this the proper way to execute a manually-built command line from a powershell script? I thought initially that Invoke-Command would do it, but I must have been doing something wrong because I couldn’t get that working at all for half an hour, and I got this working almost immediately.

I’ve followed this same pattern a few other times in this same script. Is this a best-practice?

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1 Answer

  1. Editorial Team

    Looks fine to me. Only thing I’d change is to use more Powershell features in place of fragile assumptions. E.g.:

    • use Join-Path instead of string concatenation

    • use the Env:\ provider to look up the %programfiles(x86)% dir (or better yet, use the HKML:\ provider to find the path – it’s in SOFTWARE\Microsoft\VisualStudio\\InstallDir)

    • when I have to write a string that contains literal doublequotes and variable expansion, I usually fall back to the syntax below. Personal preference, obviously.

      '"{0}" "{1}" /build "{2}"' -f $devenv, $solutionPath, $releaseProfile

    In some cases I’d be inclined to use Process.Start() so that I could capture the stdout & stderr streams independently (and maybe even control stdin interactively, depending on the application).

    PS – the ‘&’ is not strictly necessary.

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