Use variable inside Invoke-Expression string

Question

Very new to Powershell, so I'm not sure I'm doing things the right way at the moment, but I'm struggling pass a variable into an Invoke-Expression string and was hoping someone would be able to help.

$projectLocation = "C:/Users/Admin/Desktop/Projects/repo"

Invoke-Expression 'cmd /c start powershell -Command {
     cd $projectLocation;
     git pull
}'

I've also tried splitting out the string with ' + $projectLocation + ', but still not having much luck.

The only way I've achieved my goal is by inserting the $projectLocation string manually.

I don't think I'm far off, but any help would be great! Thanks.

Why don't you launch powershell directly or use Start-Process from within powershell? Invoke-Expression seems wholy unnecessary here. What is the actual goal you're trying to achieve here? — Mathias R. Jessen
– Mathias R. Jessen, Commented Jul 19, 2019 at 8:42
@MathiasR.Jessen do you have an example? I'm currently learning as I'm going so don't really understand the ins and outs of what powershell is and isn't capable of right now. My goal here is to create a "front-end" for non-technical users to git checkout master/branches and pull so they don't have to worry about remembering commands etc. — Nick
– Nick, Commented Jul 19, 2019 at 8:49
@Olaf that worked as expected, thank you! I'll stick with that for now, but it seems like there's probably a "better" way of achieving this that I'll look into too. Thanks a lot :) — Nick
– Nick, Commented Jul 19, 2019 at 8:53
@Nick: mathias answer is exactly what the way you should be using in production. Clean and neat way. You do not require to use Invoke-Expression — Ranadip Dutta
– Ranadip Dutta, Commented Jul 19, 2019 at 8:54

Mathias R. Jessen · Accepted Answer · 2019-07-19 08:59:22Z

3

Evaluating a piece of code that spawns cmd in order to launch a new instance of powershell.exe is completely unnecessary:

$projectLocation = "C:/Users/Admin/Desktop/Projects/repo"
cd $projectLocation
git pull

If you want to suppress any output it might generate, just wrap it in a block or function and redirect the output streams to $null:

function Pull-Repo
{
    param(
      [string]
      $projectLocation = "C:/Users/Admin/Desktop/Projects/repo"
    )

    Push-Location $projectLocation
    git pull
    Pop-Location
}

# suppress all output
Pull-Repo *> $null

edited Jul 19, 2019 at 8:59

answered Jul 19, 2019 at 8:53

Mathias R. Jessen

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4 Comments

Nick Over a year ago

The reason I'm re-opening powershell in this instance it to keep my "dashboard" for lack of a better term clean. So the user can just use that to input their options. I appreciate that my code example doesn't really give a picture of what I'm trying to achieve though!

Nick Over a year ago

Here's an image of my "front-end" So for example, submitting "2" would git checkout master and git pull. (Separate powershell instance" ibb.co/VThV7Fc I've just seen your update. That looks exactly like what I'm after :)

Nick Over a year ago

Thanks a lot for your help Mathias, really appreciate your time!

Mathias R. Jessen Over a year ago

Cool, happy to help!

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